Conference 7.286::home_work

If you live in Mass. you can have Mass Save do a computer energy audit of
your house. They can tell you how much you can save from the extra insulation
as well as from other suggestions. All it costs is $10. Computers do come
in handy :-)

                             Fred

I agree with .1 to get Mass Save to do an audit... I had it done when
I used to live in Arlington. I don't know if they still have a backlog,
but I had to wait awhile till they got to me. I don't think there is
any question that there will be some significant difference between
6 inches and 12 inches in your attic. Most of your heat loss is thru
the attic since hot air rises. Assuming you 'diy', you can probably
get the cost below $300 (watch for insul sales). If the existing insul
is at or near the top of the attic joists, then place the new insul
perpendicular to the existing insul/joists. This way, you have one
continous blanket of insul, when you butt each batt of insul next to
each other.

I am putting insul in my basement ceiling now... beware of the stuff:
don't wear contacts, wear goggles, and after working with the stuff
take a cool shower to wash off the fibers from your skin (a hot shower
opens the pores, and the fibers enter the pores, making you itch for days)

Dave L

There may be some other things you could do first that would give you
more return for the dollars spent.  Sealing up windows with $2.00 worth
of Mortite may save you more than $300 worth of insulation...but it
all depends.  In general, do the stuff that gives you the biggest percentage
return (i.e. the quickest payback for the money spent) first, then move
on to the less optimum stuff.
Charlie Wing's book "From The Walls In" (I think) has a discussion of all
this stuff.
Or go for the $10 energy audit.  I've never gotten around to having it done,
but from all I've heard they are good, and will generally tell you what you
ought to do first, second, etc.  And that all depends on your house.  If
you already have tight windows, no drafts, etc., more insulation in the 
attic may be the next logical thing to do.  

Steve

Ditto on .2's suggestions, but be sure to wear a good dust mask.  That same
stuff in your throat can make you cough for a long time.  It is definitely
a non-productive cough and it only gives you a sore throat (voice of 
experience).

Bruce Bretschneider

re: .0

Whether or not to add more insulation depends on where the "losses" are.

The state of NH used to give away energy calculation books (there's probably
one in your library). 

          
Unless the rest of the walls, floors, windows are optimaly insulated, 
it might be a waste of time adding the extra attic insulation.

In the small 5 room cape I had in Concord, NH, there was a max of 6" insulation
in the attic, and our electric heating bill (1980-1984) never exceeded $800
per year (very efficient). We also practiced "set back" during the day and
late night.
                                    
(Concord NH is a "usual" cold spot).

All this talk about DIY fiberglass installation makes me itch just thinking
about it!

-- Ward 

    Yes. I recently re-insulated the outside walls on a few of my rooms
    (while I had the sheet-rock down) with fiberglas and learned very
    quickly to wear a mask... Coal miners may suffer from Black Lung, but
    DIY'ers can suffer from Pink Lung...

-mike

...and another thing...if you add insul. to the attic it cant be foil or
kraft paper on one side so you'll have to get insulation without this, or
do as I did since it was cheaper - take the kraft paper off..

Rick

Warning! I bought an electric heat house (a two story colonial) and the people
who sold it to us where big on insulating the attic.  We been trying to fix
it ever since.  What happens is that electric heat tends to hold moisture.
As a result, flies bees and all sorts of other creatures decieded to make
my attic insulation there home.  Weve gone through a lot of pain to get
rid of them but the eggs keep hatching and its been 2 years, we havent been
successful yet.

EM

If you are contemplating insulation, or any other energy saving improvement, DO
IT NOW! YOU HAVE 15 DAYS LEFT! That is when the federal energy saving tax credit
ends. Whatever you spend this year, you get a percentage of it back on your
taxes. It's not a deduction that you have to itemize to get, but a TAX CREDIT.
It comes right out of that check that you have to write to the IRS. But the law
expires at the end of the year, so you must DO IT NOW. 

In the past few years I put in insulation, storm windows, smart thermostat,
outlet draft blocks, and a water heater blanket. I then got 15% (I think that is
the right amount) of what I spent back on April 15th, PLUS the energy savings
for the past 3 years. I think that the bigest saving came from the thermostat.
Given the record cold in Chicago the past few years, it paid for itself in about
2-3 months! 

"Check your tax advisor for details"

	Also, I  would  advise from experience that any clothes that you
    where  while  insulating  either  be  thrown out after use or washed
    separately at least 4 times.

	It only  took  one  time  for me to remember. I put on a "clean"
    T-shirt  under  my  dress shirt one morning, went to work, and about
    10:00  became  painfully aware that it was one of the T-shirts I had
    worn  while  insullating.  I  dashed  to  the  mens room and removed
    the  T-shirt, but it was too late. I was in itchy agony for the rest
    of the day. Took at least 3 more washings to make it wearable again.
    Also,  the fibers will transfer to other clothing in the wash unless
    you separate them.

					    Mark

           I just bought an eighty + year old house and when i looked in
the attic there was insulation ( roll type with facing) about three inches
or so thick, this insulation is probably about 40 years old. i'm quessing 
this by the amount of dust accumulated. my question is: is this insulation
still good? how can i tell? If it is i'm going to put more insulation on 
top of it. let me know if someone out there has had a simular experience.

              Paul

Insulation doesn't go bad.

Paul

Go ahead and put additional insulation on top of what is already there!!!

Joe

...unless, of course, you'd like to have a vapor barrier there.  3" sounds 
easy enough to remove for this purpose.

    				David Larrick

I assume the facing on the existing insulation is a vapor barrier (which
ought to be on the heated side, i.e. "down" in an attic floor).  It may
not be totally effective as a vapor barrier, but if you have halfway
decent ventilation in your attic it will probably by good enough so you
can just put more insulation over it.  My father and I did that at my
parent's house a few years ago and there have been no problems with
excess condensation in the attic or anything.  There was a thin layer of
early-1950's insulation already there, with a vapor barrier, and we just
put 6" of unfaced fiberglass on top of it.

Steve

    My older brother has a large unfinished attic with no floor; just some
    insulation between the rafters. He wants to add more insulation to the
    floor and put down some floor covering in order to use the attic for
    storage (not enough height for living space). 

    He was also going to insulate under the roof. I had heard (and I don't
    remember where) that it was better to put a good insulating barrier
    between the living space and the attic and to leave the attic cold
    (especially in snow areas). Is this true?

    Also the roof has a got quite a bit of mildew forming. The attic is
    currently non-ventilated (I naturally suggested ventilation). Good
    advice?
    
-mike

    Yes, ventilate unheated areas (in this case, the attic).  
    Since he's not going to use the attic as living space, by all means
    put insulation in the floor, with the vapor barrier (kraft paper
    or foil face) down.  
    As far as insulating the roof, I'm not sure.  It would probably
    keep the attic slightly cooler in the summer, but I would guess
    he could achieve more benefit by using the money to install a 
    good big attic fan.
    Note that if he does insulate the roof, he must be sure to maintain
    a ventilation space between the insulation and the roof, and the
    vapor barrier goes towards the attic; in effect, each space between
    a rafter becomes a long thin attic with extemely low headroom.
    To do it properly he'd need to put strip vents the entire length
    of the soffits, and put a strip vent along the peak, so each rafter
    space would be ventilated top and bottom.  (Of course, that's the
    best way to ventilate the main attic anyway, whether or not he
    insulates the roof.)
    I don't believe insulation in the roof would be worth doing unless
    he wants the attic as living space.  Personally, I'd do a good job 
    insulating the floor, ventilate the main attic, and be satisfied.
    
    Steve    

    I note first that I'm almost a year behind the last reply on this
    subject, so what I say will probably make little difference since
    few will read it.
     However it pains me to hear of all the scratching & itching
    going on in the US. I am violently alergic to fibreglass matting
    & insulation (To the point where I can tell if it's being kept in
    a cupboard without opening the doors)
     I have found the solution  to be expanded polystyrene balls , of
    the type used to make celing tiles (though obviously as seperate
    balls in this instance). I write from the UK where they can be obtained
    easily from most DIY stores in massive bags. the price compares
    with fibreglass insulation fairly well (or did when I priced it 2 years
    ago) and the advantages are numerous: No masks, No festering packaging
    to dispose of, No special clothing required, no waste (since it
    is poured into the required spaces). No cutting up to fit around
    those fiddly little bits,but most of all NO SODDING ITCHING FOR
    DAYS AFTER!!.
    I would add that the material is treated with some sort if
    fire-proofing agent, for those of you paranoid about your roof burning
    away the first time you drop a lighter in the attic while looking
    for the cat. Though I can't say I've ever made a serious attempt
    to set the stuff alight.
    Lets face it folks, if the fire in the house is up as far as the
    attic then I would suggest you missed the time to worry about fire
    risks some time back.
    
    Ca you get this stuff in the US? - I have no idea, being just a
    simple English guy who has seen little of how the rest of the world
    goes by. I'v never seen it on Kojak, The Cosby Show or Dallas (unless
    that's what they use in the shoulder pads?) so maybe you can't.
    
     I'm interested to know if this is a technological first by the
    Brits? - any observations?
    

    Now then.........  condensation, 
    I recently moved into a terraced house (in the UK by the way)
    I have condensation in my attic to the point that in the winter
    months it almost rains up there!. There is plenty of ventilation,
    (I can see light all around the eves) ,though the insulation is
    poor, this I know because the snow always goes off my roof first.	
    I presume that more insulation will cut down the attic temperature,
    thereby reducing the condensation. 
    Being a terraced house it is ludicriously cheap to heat anyway
    (approx $240 a year even with the english weather)so I have no
     particular wish to lash out cash unless it will cure the problem. 
     What I want to know is will it? (cure condensation that is?)
    

                Sounds like you have three problems!
                
                1. Little or no vapor barrier - the moisture is probably
        coming up out of the house below. A vapor barrier is supposed to
        prevent this.
                
                2. Poor insulation - there is obviously too much heat
        escaping.
                
                3. And the worst - poor ventilation! - I know you said
        that you could see light all around the eaves; but the results
        you are seeing prove that the ventilation is poor. I'll bet that
        all the openings are at the eaves, and that there is no
        outlet(s) up high. A ridge vent is the best solution. (And it
        shouldn't be that expensive either.)
                
                /s/     Bob

    I've never seen it sold as insulation, but sure, you can buy it.
    Polystyrene is normally quite flamable (wasn't that what was in
    the Apollo that burned?), and although I'm sure it can be
    flame-proofed it does give off *nasty* fumes when burning.
    
    		George

If your attic has like 6" joists (I believe many do) and you put in
R-30, be it fiberglass bats or blown celluose - your insulation will
come up above your joists.  Was wondering if anyone had any ideas or
experience on how to make the attic usable again, and what it would
cost.  My attic would be real nice for storage, IF i could lay
flooring. 

If you don't want to lose the floor, the only solution that comes to 
mind is go with one of the higher R value insulations like styrofoam.
Costs more, but will take up less room.

-mark

    uh, didn't someone suggest (in another note) laying some more 2x6s
    at right angles to the ones you've got, and parking the new insulation
    in between them?  I don't know how well that would work though (weight
    might be a problem, as well as possibly cracking the ceiling plaster
    with the hammering).
    
    Can you lay styrofoam or its cousins on the 2x6s, then lay boards
    on top of that, and then walk on it without damaging it?
    
    Dick
    

      If your attic has 6" joists you should be very careful about using
      it, even for storage.  2x8"  is  about the minimum size joist that
      will safely carry a load over  even  a 6-8 foot span.  Even if you
      only store things up  there,  you  risk  craking the ceiling below
      when you go up to get or place things.
      
      This is not to say that  you house isn't "solid".  It probably is.
      It just isn't designed to have the attic used.

    I'm looking for additional storage space in my house (who isn't)
    and are considering the attic. My problem is that my ceiling joists
    (the attic's floor joist) are either 2x6 or 2x8's and I have 12"+
    of blown in insulation covering them. I thought that I could perhaps
    run 2x6's perpendicular to the existing ceiling joist (to get me
    above the loose insulation) and lay 5/8" plywood over. 
    
    Has anyone done anything like this?
    
    Will this cause problems with cracking ceiling plaster on the floor
    below (if the existing ceiling joists are only 2x6)?
    
    

    > I thought that I could perhaps run 2x6's perpendicular to the existing 
    > ceiling joist (to get me above the loose insulation) and lay 5/8"
    > plywood over. 
    
    This is exactly what I did. I have 9" roll insulation within the ceiling
    joist. After reading a few consumer books about attic insulating
    in the Northeast I found that (according to the book) 9" was acceptable
    but slightly less than recommended for the temps. we see in the
    Northeast. Soooo, I laid rough 2X6's perpendicular to the existing
    ceiling joists on 24" centers and insulated between..then put down
    1/2" plywood. I have all sorts of Christmas stuff and $#%@& ect.
    ......Everything else you could think of putting up there.
     
    > Will this cause problems with cracking ceiling plaster on the floor
    > below (if the existing ceiling joists are only 2x6)?
    
    Don't know...My upstairs was totally unfinished when I did this
    work. I would think with all the weight being distributed (i.e.
    the inherent structure) cracking problems would be minimized.
    
    MArk

    I also did the same, except I ran 2X6s parallel (on top of) the
    2X6 ceiling joists and then layed plywood over that. Mine was also
    done during new construction so that the ceiling joist were
    pre-stressed before the ceiling sheetrock was applied and no cracks
    have appeared. I have no idea what would happen if you did it as a 
    retro-fit. The ceilings below may or may not crack.
    
    One important thing to watch out for... At first I had 12 inches
    of insulation in the 12 inch space. During the first year I noticed
    moisture collection on the underside of the plywood decking. House
    moisture working its way through the insulation, hits the cold plywood
    and condenses! I managed to pull out the top three inches of insulation
    from each row (fortunatly I had installed it as 6" faced and then
    2 layers of 3" unfaced). Now I have a 3" gap between the insulation
    and the plywood for moisture to escape. If I were to do it over,
    I would use large lumber 2x8 or 2X10 so that the gap would be at
    least 6".

    Charly
    

RE: .-1 = sounds like one should put a vapor barrier UNDER the insulation.

    The first layer of insulation has the Kraftpaper side (facing down
    of course). At the time this was done, the consenses of the different
    sources consulted recommended plastic on the walls for a vapor barrier
    but NONE on the ceiling other than the Paper side of the insulation.
    
    Regardless of the type and quality of vapor barriers, I believe
    some mositure will get through, especially in the dead of winter,
    in which case that moisture must be allowed access to the outside
    air.
    
    Charly
    

	i just had fiberglass insulation blown into my attic
	last night. 

	i got 10" (R-30) to lay on top of my 3 1/2 inches to give
 	me R40 in the attic.

	the cost was $0.40 per square ft for R-30 blown in and seems
	to be the same cost as laying R-30 batts without all the 
	agravation of attic laying.

	if you are in the worcester area and looking at prices, give
	Progress insulation in Sutton a call. they will also blow
	in cellulose but it costs more than the fiberglass.

	bob

    I have 10 inches of blown in insulation in my attic and
    have been contemplating finishing it into a game room or
    building a loft overlooking the master bedroom and I guess
    I could shovel the stuff to the far end of the attic. (if I
    wasn't going to finish the entire space)  My question is,
    it's 2x6 floor joists, and I would guess there are probably
    a lot of bearing walls under them (by the layout of the bedrooms
    below)could I double up the 2x6's to make it strong enough?
    If not, then it might just end up a cathedral ceiling with
    skylights over the master bedroom, but I hate to lose all
    that space.  It must be ~28' x ~24' up there(of course not
    all at 7+' high).
    
    					Eric
    

I want to add 6" more insulation and do so at 90 degrees to the existing 
batts. The house is about 20 years old and has 3" batts between 2X6 
ceiling joists, vapor barrier on the cold side.

The question is should I be terribly concerned about the position of the 
existing vapor barrier if I put 6" unfaced roll insulation over the top?

If I merely put it over the top, will there be a great chance of
moisture build-up? The attic area is well vented with 30' of ridge
venting and 8 each 65 sq. in. soffit vents...

Has anyone added insulation in a similar situation and if so, what 
was/is the outcome? I'd like to avoid turning the old insulation over so 
that the vapor barrier is 'down' towards the heated side.

Thanks...
	Chris

    Technically, your vapor barrier is on the wrong side. You could
    try to strip it off before you add insulation, it should tear off
    quite easily, or slash it with a utility knife.
    
    Charly
    

    I need some info about a product they use as a vapor barrier (?
    or air passage). This stuff is placed between the roof and the 
    insulation to create an air passage for breathing reasons. I have
    6 inch beams and want to use 6" x 15" insulation.
     
    I would like to know the name of it, how much, where I can get it,
    are there different types (if so what is the best and why) and what
    kind of material is it made from.
    
    
    		      =================== roof
    		      ---             ---
		      ###\   1/2 "   /### what is the name of this 
    		      ####-----------####
		      ###################
    		      ################### insulation
    		      ###################

    They go by at least one name, "shoot vents", they are made of styrofoam
    and can by purchased at Grossman's, each piece is about 3' long
    and they are about $1.00 each....

    just staple them between the rafters and them install your insulation.
    make sure they travel from the soffit vent to the ridge vent.
    
    
    
    Royce

    The stuff I used is called Propa-Vent. It comes in 8ft. lengths,
    its made of styrofoam, it looks just like the drawing in 1951.0.
    It fairly inexpensive and any lumber yard or home improvement
    place should have it. You just staple it up to the underside
    of the roof before you put up the insulation. Its simple to use
    but very important.
    
    Bob

    I used Propa-Vent myself.  My installation was on a hip roof right
    at the hip where the insulation pinched tight to the sheathing.
    
    This stuff must be one of the better kept building secrets, like,
    I think the building inspectors just lay in wait for unsuspecting
    D.I.Y.ers to catch them on this type of detail.

    It is for venting not a vapor barrier. You are going to be using
    unfaced insulation? Because for ceilings and floors you do not use
    a vapor barrier.
    paul
    
    

>    Because for ceilings and floors you do not use a vapor barrier.
    
You most certainly do.  Just make sure that the vapor barrier is facing the 
warm side of the insulation.

Paul

    Re: Vapor Barrier,
    
    I agree (although I'm not sure why) that you install vapor barriers on
    walls but not ceilings or floors. All of my past sources of information
    seem to agree on this one. 
    
    But, as recently pointed out in question & answer column ( I forget
    where) that kraft paper back insulation does not provide a vapor
    barrier.  I think the context of the question was wether or not the
    kraft paper should be sliced or removed before installing plastic over
    it for a vapor barrier. The insulation manufacturer's response was that
    slicing or removing was not necessary since the kraft paper doesn't
    provide much of a barrier especially with seams every 16". 
    
    Charly

    
    
    	I recently bought them at Grossman,s for $2.00 each. Look around
    where they keep the styro-foam wall insulation sheets. 
        
    	I was doing the same type of job - 6" ceiling joist using 
    6" x 15" insulation. The shoots were 4' in length and I found that 
    cutting then in half still gave plenty of length to get above the
    insulation, as well as cutting my cost in half.
    	Another thing you might want to consider (when you have a few
    extra dollars) is to put another layer of unfaced unsulation over
    the 6" - but this time laying it in the opposite direction - this gives
    a higher R-value as well as sealing up any spaces between insulation 
    and ceiling joist.

    
    	Ray.

    
    
    	BTW - forgot to mention - they come two together - so you might not
    recgonize them at first glance.
    
    
    
                 detach here__
                              |
                              |                             
               ___          ______         ___
                  \________/      \_______/

    
    
    

    
    re -.5 
    
    what gives you the idea that you are to use a vapor barrier everywhere?
    then how do you expext to get all the moisture that is generated
    (shower,doing dishes etc. also what is in the cellar) out of the
    house.
     paul

    I never heard of not using a vapor barrier in attic and floor
    insulation. The idea of using faced insulation is protecting the
    insulation from getting water soaked from moisture passing through
    the walls/ceilings. there is enough other ways for moisture to get
    out. You DO NOT want it to pass through the insulation. 
    
    Bob 

    	I think there might be a bit of confusion on what were talking
    about. When I first read the not which said not to use vapor barrier
    in ceilings I just about fell out of my chair, Mainly because I
    was thinking back to the orginal not which involved insulation between
    roof rafters. So I assumed we were talking cathderal ceilings which
    should be treated like walls and as such vapor barriered. Now if
    we are talking ceilings with an unfinished attic above there is
    now need for vapor barrier as there is now cold surface next to
    the insulation for the moisture to condensate on. The same is true
    for the floor. 
    	The main purpose for the vapor barrier is to keep moisture from
    passing through the insulation and condensing on a cold surface
    next to the insulation. If there is no cold surface there is no
    need for vapor barrier.
    
    ...Dave
    

    okay lets try this if you have a heated basement with either dirt
    or very pourous floor which way would you install vapor barrier?
    also bact to the vents The only time I have seen these used is 
    when you install blown in insulation on the attic floor, so that
    you don't block the ridge vents! 
    
    Now back to the first sentence the answer is YOU DON'T otherwise
    you trap the moisture in the basement and end up rotting everything
    away.
    
    

    < Note 1951.13 by ATEAM::COVIELLO >
>    when you install blown in insulation on the attic floor, so that
>    you don't block the ridge vents! 
			 ^^^^^
        
	Holy macarel!!  How much insulation you putting in your attic??
    ;-)  Don't you mean soffit vents??  
    
    Phil

    	He could also mean HIX or HICKS vents, the kind that are drip
    edge and vent all in one.
    
    	I have this styro foam stuff in the cathedral ceiling of my
    family room and its purpose is to keep an open channel of air moving
    between the insulation and roof shething. It allows air to pass
    from (in my case) the HICKS vents up into a large air space on the
    other side of the cathedral ceiling which is vented by a roof vent.
    
    ...Dave
    

>    okay lets try this if you have a heated basement with either dirt
>    or very pourous floor which way would you install vapor barrier?

	A) A vapor barrier is ALWAYS installed facing the WARMER side.

	B) Excessive moisture should be controlled at the source.	
         

	Damp basement floors can be "waterproofed" or plastic applied.
	Bathrooms should have exhaust fans venting to the outside.

  I have a dirt cellar and will be installing insulation with the vapor barrier
  against the underside of the floor boards.  I also plan to seal as much of
  the dirt area with polyethylene film.  The basement walls are naturally
  "well ventilated"(fieldstone).

							-=Dennis

This is starting to sound like a cheap novel.  I can't believe how many people
are so sure of their answers and are wrong at the same time, although the 
majority ARE correct.  The following ARE all true statements:

	o	you DO need a vapor barrior
	o	the vapor barrior should ALWAYS be on the warm side (even though
		some builders incorrectly put the vapor barrior in the cellar
		on the cold side)
	o	you ALWAYS need a space for air to flow on the cold side of the
		insulation (ceilings only)

The parts I'm not sure of though I believe both to be be valid are:

	o	lack of a vapor barrior will cause moisture to get both the
		insulation wet AND condense on the underside of you roof rafters
		causing them to ROT!!!
	o	wet insulation doesn't, although if it does get wet you can 
		simply wait for it to dry out, the catch being until it does so
		it will be of no value to you

-mark

    I'm not going to touch the vapor barrier issue, I get enough arguments
    in SOAPBOX. But an aside to a previous about the styro venting,
    that look like __           ____          __ that, I just bought
                     \_________/    \________/
    some and installed it this last weekend, and they had 4 ft lenghts
    in double wide as shown above for $1.29, single for $1.19. one is
    for 23" and the other for 12" or 16". The smaller is exactly half
    the size of the larger. So be careful about the price, save some
    bucks. BTW, they are called soffit vents.
    
    Colorado Bob    
    
    

    Thanks for your answers, but now I am confused, I also have been
    told that a vapor barrier in an attic is a personel preference
    issue. There are pro's and con's to this issue. The big concern
    is that you allow an air passage so the attic (new attic) can 
    breathe therefore allowing the air to move, thus reducing condensation.
    
    re .7:  I only have 6" joists/beams, and it is not a good idea to
    compress insulation, it actually brings down the R-value of the
    insulation.
    
    Luke

	I have an all electric house with 6" bats under the floors, or 
in the ceiling of the basement.  There is no vapor barrier which seems
to concur with the 'no cold surface against the insulation' theory.
Now when I go to finish the basement, which will include sheetrocked
ceilings, how do I answer the vapor barrier question??  Should the VP
go on the 'basement side' of the insulation??  Both sides??  Should
I remove the insulation all together??

Brad.

    Leave the insulation it will act as a noise barrier DO NOT PUT UP
    A VAPOR BARRIER because this will restrict the flow of moisture
    up thru the house, and out thru the soffit vents (not ridge vents).
    
    I have a feeling some of you will not like this. sorry, but I do
    run a construction business and I have done it this way for years.
    
    paul

    I can't stand watching this one any more without jumping in.....
    
    Re: .21
    
>>      Leave the insulation it will act as a noise barrier DO NOT PUT UP
>>  A VAPOR BARRIER because this will restrict the flow of moisture
>>  up thru the house, and out thru the soffit vents (not ridge vents).
  
    I agree this is what will happen, and that it is standard practice
    around here.  I'm not sure that makes it *good* practice.
   
    There are two extremes of house construction that seem to be balanced
    for New England -- the old, uninsulated, highly leaky houses that
    use enormnous amounts of heat, and superinsulated, virtually airtight
    houses that use little heat.
    
    The old kind has you heating and circulating a lot of air, so there's
    little humidity buildup, and there's no insulation for the moisture
    to condense in.
    
    The new kind has what amounts to an airtight membrane (vapor barrier)
    around the entire living space, with insulation outside it, and
    controlled exchange of air (via heat exchangers, maybe) to manager
    humidity and odor.
    
    The problem is, you can't afford to *heat* the old kind and you
    probably can't afford to *build* the superinsulated kind.
    
    So the argument is all about how to strike a compromise.
    
    .21 basically says to rely on the "stack effect" (like a chimney)
    to whisk humidity out of your house.  The problem is, the same flow
    will be pulling *heat* out the attic, by convection.  This will
    work, but it will cost you money to provide all that heated air
    carrying the water vapor.
    
    I would suggest that it would make a lot of sense to seal the attic
    floor with vapor barrier, insulate above it, and ventilate above
    the insulation.   Then your insulation works right, you minimize
    the loss of heat due to stack effect, and if you want to reduce
    the level of humidity you can briefly (and in a *controlled* way)
    open a window.
    
    dq
     
                                                             
    
     
    
    

    
    about ten years ago when I still lived at home my mother had an
    addition put on the house it was a full basement with block walls
    and poured concrete floor well my grandfather and the contractor
    decided that they would buy unfaced insulation and install a plastic
    vapor barrier floor, walls, ceiling. since there was no convenient
    way to hook up to the fha system they installed electric heat.
    during the winter the windows were sopping wet because of there
    being a vapor barrier floor and ceiling.
    paul

    Re:  .23
    
    Yes, the humidity has to be controlled.  You would have to vent
    to the outside.  The question is whether you get controlled venting
    through a vent, or uncontrolled venting through your insulation.
    
    dq

	
	re .19:


    re .7:  I only have 6" joists/beams, and it is not a good idea to
    compress insulation, it actually brings down the R-value of the
    insulation.
    
   
	I think you miss understood what was ment in note .7
 	
	this second layor of insulation should lay over the joists/beams,
	and not compress the first layor of insulation.

	 Obviously if you plan on installing some flooring in the atic
         you won't be able to do this.

    
    You only want to insulate floors when the room below is unheated.
    If you have a heated basement you don't necessarily have to insulate
    the ceiling of the basement unless for acoustics but then you don't
    want to put a vapor barrier. 
    
    The only time you need a vapor barrier is where warm moist air will
    meet COLD air. The VB should face to the heated room.
    
    When you add insulation to existing insul. it should be UNFACED.
    
    Even an unheated basement,if it is tight, may stay warm enough to
    not need a VP between floors if furnace is in that basement.
    
    my $.02
    

    re .11:
    
>>    ... Now if
>>    we are talking ceilings with an unfinished attic above there is
>>    now need for vapor barrier as there is now cold surface next to
>>    the insulation for the moisture to condensate on. The same is true
>>    for the floor. 

    The "cold surface" is the outside fringes of the insulation. If
    moist air is allowed to pass through a fiberglas batt, it cools as it
    does so. If it cools to the dew point during its journey, it will
    deposit moisture on the fibers.
    
    Try breathing through a layer of knitted material (like a scarf)
    in frigid air to prove this theory.

    Re: excess bathroom moisture
    
    I have a well-insulated electric-heated home.  My bathroom has a
    ceiling fan, which I have used religiously since I moved in in May.
    
    ...until winter hit...
    
    I was proud that my roof remained evenly snow covered after each
    storm.  But a couple of days later, I had icicles over the edge
    of the roof over the bathroom.  Investigation and experimentation
    showed that using the ceiling fan let enough heat into the attic
    to melt the snow on the roof.
    
    I have a good roof and don't want any ice build up.  So now I shower
    without the fan when there's snow on the roof, and open the bathroom
    door after to distribute the moisture into the rest of the house.
    
    Remember, this is winter.  30-50% relative humidity is good for
    you.
    
    Elaine

    RE .29 
    
    	First off I wouldn't recommend venting a bathroom exhaust fan
    into the attic. Your much better off venting it outside. 
    	
    	2nd you're right about not using it in the winter. The extra
    moisture helps if you have a dry house but if you already have enough
    you might as well use it. That's why you vent it outside and have
    it on a switch. Run it just long enough to get rid of the visable
    steam. Once you have condensation all the exhaust fans and CFMs
    in the world will not get rid of it any faster than opening a door
    and wiping off with a towel.
    
    ...Dave
    

    RE .29
    you mean to tell me that your bathroom fan is vented to the attic.
    it should be vented OUTSIDE that way you don't throw excessive moisture
    into the attic area and also have the icicles forming.
    paul

    re: .30 and .31
    
    No, the exhaust is vented through the attic and outside (the vent
    is in the soffit).  Are you suggesting that there might be a leak
    in the duct, causing the hot air to go into the attic?  COme to
    think of it, I don't know if the duct is over or under the attic
    insulation...
    
    Elaine

I've been thinking about this (and avoiding saying anything until I had 
something to say).  I think the reason that the "vapor barrier in the walls, 
but not in ceiling or floor" idea came about is because it is CRUCIAL to have a 
vapor barrier in the walls, since there is no ventilation.  In a ceiling or 
floor, the space is vented to remove the excess moisture.

Paul

    A properly ventilated attic above an insulated ceiling will always
    get cold enough in the winter around New England to condense moisture
    from the space.  That's why the roof of such a space keeps its snow.
    The comment in .11 suggests otherwise.  A ceiling vapor barrier
    in this situation is a good idea therefore.  The theory that the
    venting in the attic will carry the moisture out of the insulation
    just don't hold water ...  Besides, the frost that forms as a result
    has to melt first.  
    
    The istallation of the faced insulation has everything to do with
    how good of a vapor seal does it form.  Aren't you supposed to overlap
    the paper edges of each 16 inch roll prior to stapling into place?
    Then the wallboard should keep the seam closed too.

    Yesterday, I walked up to the attic and accidentally lay my hand
    on the attic ceiling, it was moist. It was not wet, just a little
    moist on some section but not all. The attic has two windows, one
    at each end, but both are closed. There is no other venting. I
    realize that we had lots of snow lately and the roof still is covered
    with snow.  But, is it normal to have a moist ceiling in the attic
    in winter ? or am I too sensitive.

    
    
    	No venting in the attic ? Don't sound right to me.
    
       Try leaving both windows open a crack to get some circulation
    up there.

    What's happening is the warmer air in the attic is in contact with
    the cold attic ceiling(since the ceiling is in contact with cold)and
    the moisture is condensing on the inside ceiling. I assume that
    the attic is unfinished. This is normal considering the circumstances
    and as was said in .1 the attic should be vented.
    
    
    Bob

    if your house was built like my inlaws, the windows in the attic
    were ment to be used as gable end vents and are always open..
    
    
    
    
    Royce

There was a lot of discussion elsewhere on the importance of vapor barriors
in ceilings and whether or not they're necessary.  I was going to put a comment
in their on how I've found similar condensation in the attic of my last house
and it DID have a vapor barrior and mediocre ventilation. I'd hate to think of
how much conmdensation one would get with NO vapor barrior. 

-mark

    The problem in this case that there is no ventilation in the attic,
    not wether or not there is a V.P. A vapor barrier/insulation
    combination is to protect that insulation from being damaged by
    moisture from condensation.
    
    Bob

    Whoa!, this is turning into an extension of note 1951.  That was
    a pretty heated (bad pun) discussion about ceiling insulation and
    vapor barriers.  I do not agree with re .5 about the problem not
    being the lack of a vapor barrier.  My argument is put in the form
    of a simple question:  While I'd agree that ventilation is crucial,
    how did the moisture get into the attic in the first place? and
    wasn't that what the vapor barrier was supposed to prevent?  
    
    The function of the vapor barrier is to lower the moisture content
    of the air trapped in the insulation so that the location that is
    at the dewpoint temperature (where condensation occurs) is beyond 
    the insulation.  Hopefully, this is a point in the attic that 
    is ventilated so that buildup is prevented.

    RE.6: I do agree that a v.b. will stop certain amounts of moisture
    from getting to the attic, BUT if the attic is poorly vented, no
    v.b. will stop the problems associated with poor venting. The space
    between the insulation and the roof should be @outside temp or you'll
    get icing up of gutters,shingle ice backup.etc. Therefore a v.b.
    main purpose,again is to protect the insulation otherwise why would
    you need a v.b. for the insul. in walls? That moisture is not going
    to get into the attic - it is there to protect the insluation. Usually
    the air on the non-heated side of the insul. is COLD so you can't
    stop condensation INSIDE the layers of insul. so a V.P. is used.
    So I don't think condensation can be beyond the insul. in most
    cases...............
    
    
    

Let me get this straight...

The Vapor Barrier is supposed to keep the humidity inside the house to keep
water from condensing in the insulation, but it doesn't.

So you install ventilation, thereby (partially) defeating the purpose of
the insulation!

Somehow, this doesn't sound right...  It's enough to make you use styrofoam
or some other nonporous insulation!

Jim.

    
    >"The vapor barrier is supposed to keep the humidity inside the house
    to keep water from condensing in the insulation,but it doesn't."
    
    	The v.b. certainly does greatly reduce the amount of moisture
    from getting into the insulation, otherwise why would they have
    faced insulation....
    
    
    
    >"so you install ventilation defeating the purpose of the insul."
    
    	The fact is you MUST have vents in your attic or you'll create
    all kinds of problems that I won't go into here. I think everyone
    will agree to that. But I will say that is why you usually put 
    more insulation in attic floor than you would in the walls -
    at least 9 inches(in this area).
    
    >"styrofoam or some other material"
    
    That's a good point but fiberglass has a much better R value.
                                    
    
    
    
    

    re:.9,
    
    I think we actually totally agree on this.  I think that if you
    look at a psychrometric chart, except during certain weather periods,
    the moisture in the attic will not condense if you have used a vapor
    barrier in the ceiling.  Without the vapor barrier, condensation
    is likely to occur somewhere inside the insulation.
    
    Boy, I wish I had more time to get my own ceiling insulated, etc.,
    under my unfinished attic.  The ice damming this year is as bad
    as ever.
    
    I have been pulling up my attic floorboards (10-12" pine) then laying
    a foil faced, vapor barrier paper into the joist bays (stapling
    it to the joists for support should I ever pull the ceiling laths
    down) and then pouring in bags and bags of loose fiberglass wool.
    When I bought the house there were about 30 bags of the stuff in
    the attic just waiting for someone like me to have some free time.
    Unfortunately, this technique does not seal moisture out as well
    at the joists.  I also use a good vapor proof paint at the ceiling.

	I went up into the unchartered territory in my attic last night.
	I found it very (too) well insulated with two 6" pink layers.
	I also found a disconnected duct for the kitchen exhaust fan.
	It runs perpendicular to the joists, but looks like it was supposed
	to rest on the joists.  With 12" of pink it cannot, so it is
	not connected.  The distance is about 18'.  Here's an attempt
 	at a picture:

                                               |
                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~\  <- vent in side of house
                    l  _        _       _      |
                    l | |      | |     | |     |
                    l  
                    v  ^        ^       ^
                   to         joists 
                   stove

	Should I connect the duct OVER the insulation, or run it
	over the joists between the two layers of insulation?  Are
	there any reasons to expose the duct or to sandwich it in 
	the insulation?

	Thanks.

	Elaine
    

    
    I have had 2 houses in which I upgraded from 6-12 inches insulation
    in the attic.  (One was heated by gas, one by oil)--I recovered
    the cost of materials in 18-24 months.
    
    If I had electric heat I would do it right away.          
    
    
    

    re: .23
    I don't think it matters much whether the vent line is above or between
    the layers of insulation; between should be fine, if it's easier.
    The vent should definitely be connected though; the last thing you need
    is greasy air venting into your attic!

>    The vent should definitely be connected though; the last thing you need
>    is greasy air venting into your attic!

No, that's the second last thing you need.  The LAST thing you need is flames 
from the stove grease fire shooting into the attic.  It IS a metal vent pipe, 
isn't it?

Paul

    re: .25 .26
    
    You are both right.  It is metal duct.  The top of the duct that
    is vertical from the stove IS stuffed with insulation.  I didn't
    have the heart to take it out and see how greasy it is.  I'm afraid
    to know, because the house is 6 1/2 years old.
    
    I was concerned about the pocket of air created when the top fiberglass
    bat goes over the duct.  But the duct is not that high.  I guess
    that's not my biggest problem.
    
    Maybe I'll have an entry for the "Why did they ever do that" note!
    
    Thanks.
    
    Elaine

    If you want, you can always cut the second layer of insulation to
    fit around the duct; I assume it's going perpendicular to the duct,
    and crossing over it.  You could cut the insulation on both sides
    of the duct,just a little long so it butts tightly against the sides
    of the duct, then put the cutout pieces on top of the duct.
    
    Fiberglass insulation is easy to cut, as discussed someplace else
    in this notesfile recently; get two boards, lay one down and lay
    the insulation across it where you you want to cut, mash the 
    insulation flat with the other board, and cut it with a utility
    knife.  Or, somebody else suggested big scissors.  If you're up
    in the attic you may be able to lay the insulation across the top
    of a joist and dispense with the bottom board.
    

New question:

1/2 my attic has 6 - 8" of fiberglass in open joists

1/2 my attic has 3-4" of fiberglass under floor boards.

Are these true:

1) it doesn't pay to put further insulation in the open-joist area 
without somehow further insulating the floored area

2) there is no way to further insulate the floor area without removing 
or raising the floor.

    
    1) each would have its own pay-back.
    
    2) Why not just lay the insulation right over the floor?  (if you
    don't use the attic for storage)  You could put some small poles
    as markers for where the floor is.  Stepping on it once in a while
    shouldn't hurt it.
    
    Phil

>    1) each would have its own pay-back.
    
I don't understand this - the question was - if half the attic only 
has 4" insulation, and the other half has 6", does it pay to add even 
more insulation to the side with 6"?   The answer seems to be yes.
What I don't understand:  Won't the heat just be lost through the 
less-insulated area.  For example, before I insulated my attic fan 
vent, I seemed to lose a lot of heat up the vent.  If I had insulated 
the rest of the attic more, I still would have lost heat up the vent.
This is why I don't see how adding more insulation to 1/2 an attic 
pays if the the other half is underinsulated. 
But I may be missing something...

    RE: .31
    
    I'm no insulation expert, but I can't see how putting more insulation
    over a frequently used (and heated) part of the house COULDN'T help.
    I think there is a big difference between NO insulation and not
    enough insulation.
    
    Phil

It is just like resistor networks.  Let's say (inventing the numbers)
that you have half the attic insulated at R-20 and half at R-30.
That's like connecting an 20 ohm and a 30 ohm resistor in parallel.
1/20 + 1/30 = 1/12, so it is like having an attic half the size, that
has only R-12 insulation (or your full size attic with R-24 insulation).
Suppose you add R-20 insulation to one side or the other, here's how it 
works out:

insulate more insulated side:		insulate less insulated side:

1/20 + 1/(30+20) = 1/14			1/(20+20) + 1/30 = 1/17

Double those R values to get the effective R value of your entire attic.

So in other words, the insulation is 20% more effective if placed over
the less insulated side of your attic.  Caveat: that assumes that the
same amount of heat is radiated up from your house into both sides of
your attic.  Also note that the wood floor adds something to your
R value (not much, though).  Also, insulation is much more effective
if you have a solid covering than if it is just placed between joists --
you get heat radiated through the joists, which have a much lower
R value than the fiberglass insulation.

Finally, putting an extra R-20 on both sides comes out to R-22 over
half your attic (or R44 over the whole attic), a 29% improvement on
insulating just the less insulated side.

Check out the actual R values of your insulation and see how it comes out.

	Enjoy,
	Larry

re:.-1

I'm not convinced it's that simple.  I think you're implying if I put R-1000
in on one side it will increase the overall R-Value of tha attic and that
doesn't feel right.  I suspect if you raised the R-Value on one side to around
R-30 or so (if I recall Paul Weiss is an R-40 fan), that's about the best you
could do.  Adding any more will not help and NOTHING will help the side that's
4".

-mark

re:.34

I think if you look at the numbers that Larry used, you'll find that making 
half the attic R100000000 would give you an absolute maximum R value of twice 
the R value of the other half of the attic (1/20+1/1000000000=1/20, 20X2=R40)
Makes sense - if half the attic is losing no heat, and the other half is losing 
it at R20, then the average for the whole attic is R40.

The whole point was that insulating the least-insulated area has the best 
payback.  If your walls are R20 and your windows are R2, you won't see much 
change from making the walls R30, but you'd see a lot of change from making the 
windows R5.

Paul

    re .last 3:
    
    Besides the sizes of each area that is at R-xxx, it might be useful
    to consider the typical temperatures that you're trying to maintain
    in the areas beneath.  If you have various rooms that are kept at
    different temperatures, and therefore different temperature
    differentials between each room and the attic floor above it,
    I'd think that you would have somewhat different results in your
    calculations.
    
    Dick

    You might also check whether your bathroom fan (if you have one)
    sends its exhaust into the attic.  If it does, you might be exhausting
    much moisture into your attic everytime you shower.  This was the
    case in our current and previous houses, so it might be common.
    I also might add that our previous house roof was damaged by dry-rot
    caused by the excessive moisture in the attic.  Our previous house
    was only 8 years old when we sold it, and it did have attic vents.  The
    damage caused us to have to replace the roof (including plywood).
    I quickly fixed the moisture problem in our new house after moving
    in.  This required making the bathroom fan exhaust outside,
    and not into the attic.  
                                                                
    In summary, I would find out where your moisture is coming from
    and fix it soon.
    

    More attic insulation questions:

    Our house has an attic that's unusable as living space (ceiling too low),
    but is fine for storage.  There's old kraft-faced rockwool insulation
    between the roof joists.  There's a plank subfloor over 6-inch ceiling
    joists.  Since there's no point in heating the attic and the roof needs
    to breathe, the home inspector suggested pulling down the insulation
    on the roof, ripping up the floor boards, putting down the rockwool
    plus some fiberglass, and replacing the floor boards.  This doesn't
    sound like a fun job.  I've already figured out that if I do rip up
    the floorboards, it'll be much easier to replace the flooring with plywood.

    Our MASS SAVE auditor suggested having a contractor blow in cellulose
    under the floor boards.  I'd still want to remove the rockwool.
    The insulation contractor arranged by MASS SAVE came over last night
    for an estimate for the attic, blown-in insulation for the walls, and
    attic ventilation.  (By the way, I gave him a hard time about the
    "life of the structure" warranty.  It states that they'll remove
    the old insulation and replace it if it fails.  I asked him how you
    remove blown-in insulation from walls.  He said it can't fail, but he'd
    guess they'd have to take off the plasterboard!  This is in a 1934
    house with plaster-over-wood-lath walls.  Sounds like material for
    Consumer Report's "Selling It.")

    So here are the questions:

    1.  With blown-in insulation in the attic there'll be no vapor barrier
	(unless I paint the ceilings with vapor-barrier paint -- does this
	stuff work?).  If I rip up the floor boards, I can put down a poly
	vapor barrier.  I know I'm going to get radically different answers
	(ALWAYS use/NEVER use a vapor barrier), but what's the best way to
	do this?

    2.  If I rip up the floor boards, should/can I add perpendicular joists
	on top with more insulation?  Somebody said 6-inch joists are too
	heavy.  What about 4-inch joists?  This house is very overbuilt,
	according to every contractor who's seen it.  We want to use the
	attic for storage, but nothing very heavy.

    3.  The R-value of blown-in cellulose is much better than fiberglass.
	Rockwool is somewhere in between, but I don't know if it's available
	anymore.  How can I match the R-value of the cellulose?  From the
	looks of it, the floor joists aren't evenly spaced, so some kind of
	loose insulation would be better.

   Thanks,
   Gerald

	RE: 25.37

	1. Yes, put down a plastic vapor barrier.

	2. Not necessary to put in additional joists.  You can lay down
	additional insulation then anchor posts to the existing floor
	joists, and build your floor on the posts.  Same idea as building
	a deck.

	3. You could put down two or even three layers of fiberglas and
	then use the post technique described above to rebuild the floor.

	RE: 25.37

	1. I would pull up the flooring and blowin cellulose or loose 
	fiberglass.  Loose fiberglass has the same insulating ability as
	cellulose, but will not compact as much in damp environments.  The
	disadvatage is that it is terrible to work with, so it will be hard 
	to find an installer.  Layer 6" or 8" fiberglass batts over it and
	perpendicular to the joists.  5 inches of blown in is not adequate
	for a ceiling.  Blown-in plus 8" will bring your R value upto R40.

	2. They're not rely joists.  Build a 8'x8' frame out of 2x6s at 
	16" O.C.(or 24 if 23" fiberglass is used and the sheathing is 
	strong enough).  Secure to the floor as follows about every 4 ft.

	______________________________
		|  |	|  |
		|  | 	|  |
		|  |    |  |	2x6 framework
		|  |    |  |
	________|  |____|  |__________
		|  |****|  |
		|  |****|  |
		|  |****|  |
		|__|****|__|
  	existing joist^   ^2x2 strapping or scrapes from existing floor.
	
	Fill with fiberglass and sheath with plywood or existing flooring.
	8'x8' is a sample size you can make any size, except stick with 
	4 ft increments if you use plywood to minimize cutting.  
	
	You will save a small fortune by doing most of the work yourself,
	except the blow in.  

    I think you said you want to use the attic for storage, so I assume
    you don't want to build up the floor any higher than it already
    is.  
    My father and I put fiberglass batts under their attic floor a few
    years ago, without taking it up; interesting trick!  We got some
    strips of Formica and rigged up a clamp arrangement so we could
    clamp the end of a batt of insulation between the strips of Formica,
    then used a rope to pull the Formica/insulation/Formica sandwich
    under the floorboards.  When it got through to the other side, we
    undid the clamp and slipped out the strips of Formica.  There was
    some sort-of insulation already in the joist spaces with a vapor
    barrier on it, so we just left that and used unfaced fiberglass.
    Seems to have worked fine.
    You said your joist spacing isn't very even, so maybe you can't
    use this stunt, but it sure beat pulling up the floor.
    I wouldn't be too fanatical about the vaopr barrier, if the attic
    is ventilated at all.  Those ceilings have been painted several
    times by now, so I don't think you'll have to worry much.  You
    might want to do vapor barrier paint on the bathroom ceiling, but
    otherwise I wouldn't worry about it.

I am building a study in my attic.  The attic now has 6" Kraft-faced
fiberglass batt plus 6" of loose fiberglass between and over the 2x6 joists. 

In order to keep sufficient headroom in the attic, I want to reduce the
insulation to just the joist height. 

Because the new attic study will have kneewalls, the room will actually occupy
only half the actual attic floorspace. 

I know I should place a moisture barrier on the interior face of the new
insulation I add between the rafters and between the studs of the kneewalls. 
And I know about placing styrofoam "shoot vents" against the roof sheathing.

But how do I deal with the insulation under the study portion of the attic?
Since I will use the study only for a few hours in the evening, the
temperature in the study will be allowed to fall to 40 during the remaining
hours.  I am concerned that moisture could condense in the floor insulation
and joists.


			      /\
                             /##\
                            /#  #\
                           /#    #\
                          /#  s   #\
                         /|#  t   #|\
                        / |#  u   #| \
                       /  |#  d   #|  \
                      /   |#  y   #|   \
                     /+---+--------+---+\
                      |#####??????#####|
                      |#              #|
                      |#              #|	# = Kraft-faced insulation
                      |#   2nd floor  #|        ? = Kraft or unfaced insulation
                      |#              #|
                      |#              #|


1.  I could leave the Kraft batts in place, and remove the loose fill
2.  I could remove the Kraft batts, and fill between the floor joists with 
    the loose fiberglass
3.  I could leave the Kraft batts in place, and use a second vapor barrier 
    just under the new plywood floor.

    
    	What is the R value per inch of blown cellulose?  I only have
    around 4-5 inches of it in the attic, and want to know just how
    much I'm helping by adding fiberglas in addition to it.  Thanks!
    
    							-c
    

Depends
if its real celluose then 3.7 is the number.
if its just 'fluff' then 2.2 is closer

    
    	Thanks.  How do I tell if it is "real" of "fluff"?  What I have
    almost looks like really finely shreded newspaper, if that helps.
    
    							-c

If its dense stuff, and definitely not fiberglass - then it sounds 
like you have the real thing

    
    	Well, that's good.  At least I'm currently up to R-15 then.
    If it was the fake stuff, I'd be real low.
    
    	One question -- since my insulation doesn't currently come to
    the top of the 2x6s, what should I do?  Just lay on the new insulation
    within the current joists?  Put down the insulation at 90 degree
    angles as suggested elsewhere in this notesfile and have a 1+ inch
    air gap between the insulation layers?  (That doesn't sound right
    to me at all...)  Or should I redistribute the existing insulation
    to so that the cellulose comes up to the full 6 inches (ok, 5.5
    :-) on most of the attic and put some fiberglas over that and put
    thicker fiberglas over the "open" areas?
    
    							-c

	Just put 8"unfaced attic batts over the existing insulation and 
	across the joists.  This will bring your R-value upto R-40.  
	Topping up cellulose is not fun.  I did it last fall.  In my case 
	we had 5 inches between 8 inch joists, and it was very uneven.
	It took 15 bags.

	Brian

    Three weeks ago, I went to Grossman's and bought 12 bags of cellulose
    and borrowed their blower (no charge - just a deposit) and blew
    the insulation into my attic.  You definitely need a dust mask,
    but the job only took about 1 1/2 hours.  Not difficult at all.
    

    
    	Thanks for the comments, Brian.  I think I'll do just that --
    put the unfaced batts over what is already there.  Nice and simple.
    (And much less work than picking up sections of the cellulose to
    top off other sections.)
    
    							-c

    
    	(Oops, .47 was put in while I was typing .48)
    
    	Tom,
    
    	How much did that cellulose cost you and how many inch-feet
    (?) did it cover?  (i.e. how many inches deep will one bag cover
    X number of square feet?)
    
    	Did you blow in the cellulose higher than the tops of the joists?
    
    							-c

    
    	Hmmm, another question.
    
    	In reading notes 8.19+ on insulating walls, the discussion turned
    to one of the advantages of cellulose over fiberglas -- cellulose
    doesn't require a vapor barrier while fiberglas does.  I'm not certain,
    but I think I don't have a VB in the attic.  If I put a fiberglas
    batt over the cellulose, am I asking for troubles?
    
    	I'm starting to think that I'll have to play the "move the
    cellulose to make the cellulose-portion of the attic thicker and put
    down faced fiberglas on the rest" game.  Yuck.
    
    							-c

    
    	Is it possible to put a layer of plastic over the top of the
    cellulose and place the fiberglas on top of that?
    

Craig - if you don't have a vapor barrier the 'best' thing to do is to 
just add celluose until you get up to R-30 (though R 20 or so will 
probably do you almost as much good).  If you put the fiberglas over 
the celluose, it will trap moisture, and the fiberglas will rot and 
become home to mice, etc.  There is no problem bulding up celluose 
ABOVE the joists (but the attic will be unusable).  Don't get ideas 
about sweeping up the celluose and putting a barrier under it, etc., 
unless you really want Megawork.


one thing I think you "could" do -put down fiberglass batts with the 
barrier on the BOTTOM. I don't think a vapor barrier ABOVE the celluose 
will hurt it, and the fiberglass will be above the barrier

/j

    
    
.52>    If you put the fiberglas over the celluose, it will trap moisture, and
.52>    the fiberglas will rot ...
    
.52>    one thing I think you "could" do -put down fiberglass batts with the 
.52>    barrier on the BOTTOM.                            

    Fiberglass does not rot.  Neither will it burn.
    It's made of glass (which is mostly silicon) - ever seen a pane
    of glass rot?  It can soak up moisture, that's true, but it won't rot.
    
    Cellulose, on the other hand, *can* rot!  So *don't* put
    a vapor barier *above* the cellulose.  That would trap the
    moisture in the cellulose, and guess what happens to cellulose
    when it gets wet?
    
    -tm
        

.52>    If you put the fiberglas over the celluose, it will trap moisture, and
.52>    the fiberglas will rot ...
    
>    Fiberglass does not rot.  Neither will it burn.
>    It's made of glass (which is mostly silicon) - ever seen a pane
>    of glass rot?  It can soak up moisture, that's true, but it won't rot.

never said it will burn.  MAybe "rot" isn't the correct technical 
term, but fiberglass dles absorb moisture, with smelly results which 
degrade the R-Value permanently.
    
>    Cellulose, on the other hand, *can* rot!  So *don't* put
>    a vapor barier *above* the cellulose.  That would trap the
>    moisture in the cellulose, and guess what happens to cellulose
>    when it gets wet?
    
I don't buy this - celluose can get wet, and have less R-value when 
wet, but then it dries.  Probably a vapor barrier over the celluose is 
not the best idea.  What I was trying to suggest as a workable 
solution was paper-faced fiberglass with the paper face down.  I don't 
think the paper is that good a vapor barrier, and given the choice, i 
think ther paper is better below rather than above the fiberglass.

continuing to fill will celluose is still the best solution
        

    After facing the same question -- what to do about a vapor barrier
    when adding more insulation -- we decided that the best way is to
    use the vapor barrier type primer for the ceilings.  Two coats of
    this type of primer provide a good vapor barrier.

	re.49
    
    As I recall, the cellulose was about $6.00 a bag.  Covered 25 sq
    ft at R-22.  I may not be recalling correctly, but its somewhere
    in this neighborhood.  The neat part, is the blower which I placed
    in the garage and ran 100' of hose up two stories into the attic.
    
    My wife poured the bags of insulation into the hopper, while I blew
    it around the attic.  Sure beat carrying it all the way up the stairs
    and ladder to the attic.
    

    Just used unfaced fiberglass batts.  As long as the moisture isn't
    trapped in the insulation (and it won't be, either in the cellulose
    or in the fiberglass if you don't have a vapor barrier) the insulation
    will stay dry.  And, since you say nothing about moisture condensing
    in the attic space above, I assume you have sufficient ventilation.
    Put in the unfaced fiberglass batts - in between the joists - and
    you should be fine.

    
    Re: .all
    
    	Thanks for all the comments and suggestions.  I was thinking
    about this all the way home trying to come up with a solution that
    satisfies all my wants:
    
    	1)  More insulation.
    
    	2)  No covered joists.  (As soon as I cover them, I just know
    I'll have to go to some far corner of the attic... :-)
    
    	3)  Easy to install. (Moving cellulose wouldn't really fit into
    this category.)
    
    	4)  Still maintain the ability to put a storage area in the
    attic.
    
    	5)  Does the "right thing" concerning vapor barriers, trapped
    moisture, etc., etc.
    
    	I think I have a solution that satisfies all of these.  My attic
    is 24 feet wide with 2x6 joists running width-wise.  If I put 5
    strips of 2x8s running the entire length of the attic (1 near each
    edge, 1 in the middle and 1 each halfway in), the maximum length
    between these 2x8s is around 5 feet.  That is a short enough distance,
    especially since it is supported underneath by the 2x6s every 16
    inches, that if I had to go to work in some corner of the attic,
    I could put 6 foot 2x8s "flat" from one new joist to the next to create
    a temporary work platform.  Thus, my mobility-if-required is satisfied.
    
    	This would let me add up to 8-9 more inches of cellulose if
    the urge really struck me to go with that much.  This is probably
    overkill, but the nice thing about the 2x8s is that in the area
    that I'll use as a storage area, I can still have much more insulation
    than I do today and still keep a good 2-3 inch airgap between the
    plywood and the cellulose to let moisture out.
    
    	Final (??) question -- since the "upper layer" of joists are
    running lengthwise, I have to be careful how long I make the storage
    platform to insure the removal of humidity.  Lets say a 3 inch airgap
    for discussions -- how long can the platform be?  Thanks.
    
    							-c
    
    							-c

yup - you can always add another layout of joists - this gives you 
room for twice as deep a reservoir of celluose, and you can put boards
on top. except:

1) will your attic support the extra joists (its just been mentioned 
to me on occasion that attics are sometimes not built to support a big 
load...)

2) - Craig -if you have R-15 now, you may not notice much difference 
from going to R30.  Given there's no trivial way - you might want to 
devote your energies to something more productive (I'd heard it said 
that you get 50% of your insulation from the first inch, with 
diminishing returns from there...).

Also - you will have more trouble keeping cool in the summer.  After 
wer took our condo from R 9  to R 30, there was an 'inversion' layer
of mucky heat in the upper half of the upper floor that no A/C could 
remove.....

just $.02
/j

    You receive 50% of the insulation value from the first inch, only
    if you have a total of 2" of insulation.
    
    Basically  the savings you can expect are
    
    (original u-value * area * 24 hours/day * deg days * (1 / BTU per unit of
    enery) * cost per unit of energy) - (the same equation for the new
    u-value.
    
    for example
    
    r15 = u.066
    
    (.066BTU/hour/deg/sq.ft * (24' * 1'length) * 24 hours/day * 4500
    deg days * (1/1000BTU/cubic ft. nat gas) * $0.10/cubic ft.) -
    (.033BTU/hour/deg/sq.ft * (24' * 1'length) * 24 hours/day * 4500
    deg days * (1/1000BTU/cubic ft.) *$0.10/cubic ft.) = $8.55/ft of
    length of your house/year.  A 30' long house would save $256.61
    (ignore rounding errors) per year.
    
    Not knowing the area you are in, the type of fuel or the cost of
    your fuel, I can't provide you an accurate estimation.
    
    Tom
    

    I just called Energy North in Nashua to find that natural gas sells
    for $.007358 per cu.ft.  the savings in .61 would therefore be $.63
    per foot of length of the house per year.  For the 30' long house,
    the savings would be $18.88 per year.

    
    re.60
    
    According to "Architectural Graphics Standards" 8th edition, 2"x6"
    ceiling joists, 16" OC with 12' span supporting a gypsum board ceiling
    have a live load capability of 20 pounds per square foot.  If you
    use a 2' x 8' platform the weight of the platform plus the material
    stored on it should not exceed 320 pounds.
    
    This load is limited by deflection, not by shear.  In other words
    if you exceed the design load, the joists (and attached ceiling)
    will sag into the room below; you would have to exceed it significantly
    before the joists would break.
    
    Tom
    

    
    	Thanks, Tom, just the numbers I was looking for!  From the sounds
    of it, the whole plan is a "go" now -- with the exception that we
    better not store any of my wife's boxes of books up there.
    
    							-c

>        <<< Note 25.59 by BINKLY::WINSTON "Jeff Winston (Hudson, MA)" >>>
>
>                                              ... (I'd heard it said 
>that you get 50% of your insulation from the first inch, with 
>diminishing returns from there...).

      Although 50% from the first inch is inacurate for anything greater
      that 2 inches (which is almost everything!) it is, in fact, a case
      of diminshing returns to proportion. This stems from the fact that
      the R value is the inverse of the U value.  U value is the rate of
      heat loss, which is directly proportional to the cost of heating.
      
      Since  U  = 1/R each increment of R provides a smaller and smaller
      amount of decreas in U.  Consider:
          
          "R"     "U"     Incremental
                         Decrease in "U"
           5      .20         .20
          10      .10         .10
          15      .07         .03
          20      .05         .02
          25      .04         .01
          30      .03         .01
      
      So, as you add more and more insulation, providing more and more R
      value, each added increment of insulation provides  a  lesser  and
      lesser decrease in cost.  At some point the cost of the insulation
      exceeds the savings in heating cost.  
      
      The  biggest  variable in this equation is the outside temperature
      you assume.  I think some  other  reply(s)  assumed  a  20  degree
      outside temperature. That's may be a good "average" for all winter
      long.  But on those days when the high temperature  is  in  single
      digits  and  on those sub-zero nights insulation designed for a 20
      degree outside temperature will quickly bleed away enough money to
      pay for a lot more insulation.
          
      (See also 25.61.)

    With the onset of the cooler weather this weekend, my thoughts again
    have turned to insulating my attic.  I should mention that I checked
    all the other notes on insulation and not found this question answered.
    I have an older house, about 60 years old, and needless to say it
    is poorly insulated with about 2 -3 in of rockwool.  I would like
    to add addtl insulation however there is an attic floor ( tounge
    and groove), that I do not want to rip up.  Nor do I want to build
    a double floor on top of the one there.
    
    Does anyone know of a way I can do this.  Is it possible to cut
    holes at various spots in the floor and blow in cellulose?? Has
    anyone tried this. If yes any details would be appreciated.
    
    				Thanks Paul T

    Yes you can use a hole saw and cut holes in the floor and blow in
    insulation you have to cut at least one hole per bay to make sure
    it gets in between each floor joist.  I had it done in a shed roof
    in my house and it worked very well.
    
    Paul
    

This is my first note in HOME_WORK, and I really hope someone replies to
this either in the notesfile or by mail.  Any help is appreciated!

Here is my problem (dilema?):

I  have  an  older  house  that  has  NO attic insulation what so ever! (When
MassSave came in this past summer they said  if  they  took  an  ultra-violet
picture  of  my  house  on  say Jan 1, it would look like the roof had burned
off!). Well be that as it may. I have cut a hatch hole into the  attic  area,
and  find  that  I  have  some pretty good (read the rafters are about 24" on
center) construction there. I have 10 feet across of flat flooring and 8 foot
knee-walls  on  each side ( I think I am using the correct term!). Anyway the
flat area seems straigth forward. X inches with some type of either kraft  or
foil barrier.

My  problem is the knee walls! What would be the best thing to pour/blow down
them? I also plan on cutting two vents into the peak of the house. Would  that
be enough ventilation?
                                  
A rough drawing of the second floor attic:

				^
                               / \
			      /   \
                             /Attic\
                            /       \
                           /=========\ -----
                          / <--10'--> \   ^
                         /     2nd     \ 8 ft knee walls
                        /               \ |
                       /|     Floor     |\----
                      / |               | \
                        |===============|


As usual, all help/suggestions are greatly appreciated!

Mike Buckley

i think the vertical, short walls in the upstairs are the kneewalls.  in any 
case, the slanted roof walls are what you want to insulate right?  remember,
the soffit (or eave) vents at the lowest edge of the roof are usually vented 
through this space to the attic (and are necessary).  someone makes styrofoam 
channels shaped like this ___            ___ that will keep the venting working 
                             \----------/
after you fill the spaces with loose insulation of some type.  hope this helps.
craig

    They are called PROPER-VENTS and sold with insulation.....they suggest
    that you run them from the soffit vent to the open, uninsultated space
    above the ceiling....or the the ridge vent on a vaulted ceiling.

In asking another question, Paul pointed me onto a problem I had not thought of.
Paul said I cannot just use propa-vents to insulate my hip-roof attic, because
the air flow won't be right.

I have an old house (1901) with a hip roof and a slate shingle roof.  I want
to insulate the attic CEILING.  I had planned on putting in propa-vents to alow
the air from the eaves to get to the top of the hip.  Paul says this won't work.

What can I do that won't require major construction.  There must be something
simple that is possible here.  Right?

Ed..

    I'm at the point trying to decide which type and how much
    additional insulation to add to our attic. When I bought the
    house in May the inspector noted insulation in the attic but
    that it was barely addequete to today's standards. I calculated
    the attic space and it's roughly 1150 square ft.
    
    I consdidered using figerglass. It would have to be cut to fit
    into place. It's horrible to work with in enclosed areas. Health
    considerations. Small access space to the asttic from the closet.
    
    I consdiered using the loose fill type. It's much easier to apply
    (at least I think so) there's no cutting or fitting, no health 
    hazards (that I know of, unlike figerglass). 
    
    The loose fill type is a cellulose insulation and is a product of
    recycled paper and covers 25 sq ft at R-19 for 3.75 per bag.
    
    Would this type of insulation be preferred over the fiberglass?
    or should I be looking towards somthing else?
    
    Thanks, Jim 

Well, propa vents will work, as far as they go.  But all they do is provide a
channel for air to move.  For the air to actually move, you need ventilation
at both ends.

Consider a normal roof.  Each rafter runs from the top plate of the walls up
to the ridge.  It is easy to install soffit vents and ridge vents, and this 
provides ventilation at both ends of every bay between rafters.  All the propa
vents do is connect these two ventilation points, allowing air circulation 
above the insulation.

Now consider a hip roof.  There is a hip rafter going up each corner, and the
majority of the rafters - including all the rafters on the short sides - butt
up against the hip rafters.  Each of these rafter bays is CLOSED at the top,
which means that even if you install soffit vents and propa vents, no air will
flow.  Somehow, you need to provide ventilation at the tops of those rafter
bays.

I really have no idea how to get around this.  Theoretically, with a perfect 
vapor barrier you don't need ventilation, but I wouldn't want to trust the
integrity of my roof to the perfection of the vapor barrier.  I suppose you
could put ridge vents on the hip ridges on the roof, but I don't know how that
would look, nor do I know if ridge vents are designed to be still watertight if
installed on a slope.

Any other ideas out there?

Paul

>    I consdiered using the loose fill type. It's much easier to apply
>    (at least I think so) there's no cutting or fitting, no health 
>    hazards (that I know of, unlike figerglass). 
    
I just blew in 26 bags of that stuff last week over a room addition. 
Most houses out here (Phoenix) use that stuff, maybe cause it's 
"manufactured" at a plant close by. I guess it's easier, but it sure 
makes a mess. The stuff in the bags is real compressed, you have to 
put about 1/2 a bag at a time in the blower, and have one person help 
to keep it from clogging up the orifice while the other mans the hose. 

It does fill in well between joists and in tight spots, but the dust 
it creates floats everywhere for a few days. We blew it 10 inches 
thick in our attic for an R30 (typical here due to heat). It took 
about 3 hours, and we both looked like we aged about 30 years 
afterwards due to all the grey dust everywhere. 

Get a GOOD mask and wear eye protection (sealed goggles)... it's not
fiberglass, but it sure irritates throats, lungs, eyes, etc when it
looks like you're in a blizzard of the stuff..... 


Arlan

    I have an idea which might not be a good idea structurally, but should
    solve the venting problem.  The problem, as I understand it, is that
    the rafters that meet up with the corner will have no air flow.  You
    could put a 3" hole in the rafters where they meet the corner all the 
    way up 'til the ridge vent is reached.  The air flow will go from the
    soffets up each bay and then work through the 3" holes to the ridge.
    
    This is just an idea and I don't know if it is structurally sound, but
    you can put 3" holes in the floor joists for plumbing so why not!
    
    JohnD.

To make sure I had ventilation around my skylights, which are in a cathedral
ceiling, I drilled a one inch hole in each rafter where soffit to ridge air 
flow was blocked by it.  My carpenter and building inspector said that this
would be enough.  Something on that idea may be sufficient on a hip roof.
Drill enough hole to provide ventilation while not drilling too many to cause
the roof to cave in.

    My two skylights, in the new addition, were installed the same way.
    I think there were a couple of holes drilled in the middle of the
    rafters where the air flow was blocked by the skylights.

So how can I determine how many 1 inch holes are needed without affecting the 
structural strength?  Also where would the holes go?

Ed..

    Probably a 1" hole every 2 - 3 ft/ would probably be adequate.  Make
    sure to drill them along the neutral axis (center of the width) of the 
    rafter where the structural stress are zero.

>    Probably a 1" hole every 2 - 3 ft/ would probably be adequate.  Make
>    sure to drill them along the neutral axis (center of the width) of the 
>    rafter where the structural stress are zero.

That doesn't sound right.  You need the holes at the ends, up against the hip
rafter, to get the ventilation action that you want.  And it seems like they 
need to be at the top of the rafter, not the center.  Besides, that doesn't
sound like nearly enough holes.

I don't think drilling holes at the top at the ends should be all that much of
a problem.  You couldn't do that at the center without seriously weakening the
rafter, but if I remember my structural engineering right, a chord which comes
to a point at the ends is almost the same strength as a solid beam.  If that's
true (anyone else remember?), you ought to be able to cut holes at the top
without weakening the roof.  Remember, these rafters are already overbuilt -
they are the same size as the rafters that go all the way up to the ridge, and
they are shorter.

I don't think just one 1" hole will be adequate, but I'm not sure how much you
DO need.  Remember, the holes for each bay are also ventilating all the bays 
beneath it, so the holes in the last rafter before you get to the ridge are 
ventilating the entire corner of the roof.

I think what I would do is get a 1" drill bit, and start with three holes in
the bottom rafter in the corner of the house.  I'd drill them as close to the
roof as I could and still have them parallel to the roof - this would be 
limited by the size of the drill, but I guess the holes would start about 1"
from the roof surface.  I'd drill them as close up into the corner against the
hip rafter as I could, and I'd drill them so they weren't quite overlapping -
maybe 1/4" between them.  And I think I'd add one hole for each rafter as I 
went up to the top.  That would probably be about a dozen holes in the top 
rafter.  Incidentally, I would also be mentally prepared before I even started 
to hit some of the nails holding the plywood to the rafters, to attempt to 
limit my frustration when I did, in fact, hit them.  :-)

But this is pretty speculatory.  That seems to my sensibilities like it would
add enough ventilation without weakening the roof significantly, but I have to
say that this opinion is not based on any hard facts.  Given the disastrous
possibilities of a rotten or collapsed roof if you underdo or overdo the holes,
you might need to talk with someone with more specific expertise than you'll
get in this file.

Paul

>    Probably a 1" hole every 2 - 3 ft/ would probably be adequate.  Make
>    sure to drill them along the neutral axis (center of the width) of the 
>    rafter where the structural stress are zero.

Sorry I was tired and so were my fingers... that should have read - 1" hole 
every 2 - 3 inches for a foot.

I think Paul's suggestion of increasing the number of holes as you move up
the hip rafter sounds good, although I would probably increase it 1 hole for
every 2 rafter bays.  Don't want to turn these rafters into swiss cheese,
especially with a slate roof. The total area of the holes at the last rafter
all the way around represents your intake area.  It should be some multiple
( > 1) of the exhaust area supplied by the ridge vent.  Some other note must
have info on what the multiplier should be.

Regarding hole placement along the width of the rafter see the diagram below
from Statics 101.  It is suppose to be a diagram of a roof rafter shown 
horizontally.   Drilling close to plywood roof sheathing is not bad, but
a more optimal location is closer to the center (neutral axis).   Wood is 
better at handling compressive stress than tensile stress.



                   Roof Load
    |  |  |  |  |  |  |  |  |  |  |  |  |
    v  v  v  v  v  v  v  v  v  v  v  v  v     Max. Compressive Stresses
   ======================================= <- in these topside fibers

                                    
 - - - - - - - - - - - - - - - - o o o o - - Neutral Axis, stress ~= 0
                                           ( o = 1" hole )

   ======================================= <- Max. Tension Stresses in
    /\               ^                 /\    these bottom fibers
   /  \              |                /  \
 Outside Wall        |             Hip Rafter
  support            |              support
                     \
                      `- Max. Bending Stress
                         occurs at the center 
                         of the rafter length


As Paul suggested, you'll want to get some professional advice before 
starting.
    

    I have a house with a hip roof, and here is how we handled the problem
    when we insulated and put up drywall to finish off part of the attic.
    
    When the house was built in louvered soffits and a ridge vent were
    installed.  The rafters are 2"x8".  We purchased cardboard `air
    tunnels' which were stapled to the plywood roof sheathing.  Then 6"
    fiberglass was installed between the rafters.  See following picture:
    
    Plywood sheathing -----------------------------------------------
                      -----------------------------------------------
    			|  |___	  			     ___|  |
    			|  |   \<----- `AIR TUNNEL'         /   |  |
    			|  |    \__________________________/    |  |
    Rafter------------->|  |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX|  |
    			|  |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX|  |
    			|  |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX|  |
    			|  |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX|  |
    			|  |XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX|  |
    			 -- 		    /\			 --
    					 Insulation
    
    The `air tunnel' allows air to flow from the soffit vents to the ridge
    vent.  I do not know if this will work for you.   I hope you can 
    understand the drawing.  If not give me a call or send mail.  
    
    /R.L.  DTN 367-5528  AUNTB::FULTON
    

re: .9

I'm not sure you understand what a hip roof is.  It's a roof which slopes down
in all directions, not just two, so that there is no peaked gable end.  On all
four sides of the house, the roof shingles form a complete horizontal line at
the gutter-line of the roof, so you could install gutters on all four sides if
you wished.  With this type of construction, an angled ridge is created going 
up from each corner of the house.  If the house were square, all four of these 
angled ridges would meet at a single peak.  More typically, the two from each 
end wall meet, and these peaks are connected by a normal ridge.  

The solution you describe is the standard way to insulate a normal two-sided 
roof.  The problem being discussed here is that since in a hip roof the 
rafters in the corners butt against the hip rafters (which run up the angled 
ridges), the spaces between those rafters are very difficult to vent.

If I've misunderstood you, please correct me.

Paul

    RE: .9
    
    The picture you drew is very good and illustrates how cathedral
    ceilings are insulated when the rafters run from the soffit all the
    way up to the ridge.
    
    The problem occurs in the "hip" portion of the hip roof where the
    rafters don't make it all the way up to the ridge vent.  The rafters
    in the "hip" portion are actually parallel to the ridge vent.
    
    -al

    re: .10,11
    
    Sorry.  I do know what a hip roof is.  It is what is on my house with
    the rain gutter on all 4 sides.  However, I guess I was thinking about
    what I did.  I did not finish the whole attic, but just the middle 1/2. 
    As a result, I did not have to be concerned with the ridge sections.  I
    now better understand the problem.
    
    Good luck,
    /R.L.
    

 I've seen hip roofs constructed with ridge vents also installed upon the 
 hip-rafters, but I don't think that's a good solution for anywhere but
 very dry climates.....

 The drilled holes, @ mid-rafter-depth, seem to be a good solution.
    

It seems that the concensus is to drill holes all the way up the sides.  Who
would I ask to find out how many holes would be enough without being too many?

I have already made a stab (on another project) at using a designer.  It was
less than helpful.  Is there some sort of structural engineer-type that is able
to help me with these kinds of questions?

Ed..

    If you drill your holes in a mid rafter axis as was previously
    mentioned, how is the warm air going to flow into the holes if their
    covered by insulation...??? This is of course your going use the
    maximum rafter space available yet still have room for your air
    channel.  One thing to remember is to leave the last couple of inches
    free of proper vent to allow the air to move between rafters till it
    reaches the ridge vent.
    
    I would think you would want the holes drilled as close to the
    intersection of the sheathing/hip rafter/rafter as possible...
    Also to create a better more efficient draft you would only want the
    holes drilled in the upper ends not along the whole length of the
    rafter.  
                             1" holes
                                 \
    ==============================\=====---====  <--  sheathing
                                  O O O | |
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| |
    XXXXXXXXX insulation XXXXXXXXXXXXXXX| | \
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| |  \
    --------============================---   \
         /         /                           \
        /      drywall                          hip rafter
      rafter
    
    I would think that the fact that warm air rises would create enough of
    a draft to keep the number of holes needed to be drilled to a minimum.
    I would think 3- 1" holes per rafter would be sufficient, I'm not a
    rocket scientist but common sense tells me this would be enough.
    
    Fra 

    I don't understand where you are drilling your holes.  It looks like
    you are drilling holes in the sheathing.  The sheathing would be
    covered with underlayment and shingles.  Where is the air flow?
    
    You want the holes in the hip rafter so that it will open to the other
    channel leading to a soffit vent.

    lets try this again:
    
    i'm assuming the 4 corner rafters are the hip rafters... correct?
    
               R O O F   L O A D       R O O F    L O A D
        |	|	|	|	|	|	|
    	|	|	|	|	|	|	|
    	V	V	V	V	V	V	V
    ---------------------------------------------------------- SHINGLES
    ---------------------------------------------------------- PLYWOOD
    						     O  O  O  |
                                                              | RAFTER END
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX| (HIP END)
    XXXXXXXXXXXXXXXXXXXX INSULATION XXXXXXXXXXXXXXXXXXXXXXXXXX|
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX|
     \
    (SILL END)
    
    The holes would be drilled in each rafter that would butt the hip
    rafter (locations approx 1" below roofing). The air would flow up the
    bay until it reached the hip rafter, then enter the holes, thereby
    moving to the next bay, and so on till it eventually reached the ridge
    vent.  By locating the holes not only as close as possible to the end
    of the rafter but also as close to the sheathing, you are creating a
    better air flow into the next bay.
    
    If you refer to (.8) the only difference would be that the hole
    locations would be closer to the upper edge of the rafter.
    
    hope this helps...  any questions call me,  227-3038
    
    drawing in notesfiles is not easy.
    
    Fra
    
    

I am still a bit confused about why I need holes.  The eaves are open to the 
outside.  Why wouldn't air simply flow into the vents and up the channels?  If
there are any rafters blocking the flow from bottom to top, I would have to
put holes to open this flow.  But why do I need holes to open the flow to the
other channels?  

Ed..

    ed,
    
    When the air flows up your channel and hits the hip rafter, where will
    it go???  you have to open up the flow to the next channel and so on
    till you reach the ridge, otherwise you'll have dead air in each bay.
    
    lets try this ONE MORE TIME:
 
                           EAVE 
  _____________________________________________________________
 | \ A |   |   |   |   |   |   |   |   |   |   |   |   |   | L /|   
 | E \ | B |   |   |   |   |   |   |   |   |   |   |   | K | / M| 
 | ____\   |   |   |   |   |   |   |   |   |   |   |   |   / ___| 
 |    F  \ | C |   |   |   |   |   |   |   |   |   | J | /  N   |
 | ________\   |   |   |   |   |   |   |   |   |   |   /________| e    
 |        G  \ | D |   |   |   |   |   |   |   | I | /   O      | a
 | ____________\   |   |   |   |   |   |   |   |   /____________| v     
 |            H  \ |   |   |   |   |   |   |   | /   P          | e
 | ________________\___|___| ridge vent|___|___/________________|  
 |                 /   |   |   |   |   |   |   \                |
      hip rafter /                               \ hip rafter
    
> "but why do i need holes to open the the flow to the other channels?"
    
    If there are no holes in the upper ends of bays a,b,c,d,e,f,g,h,i,j,
    etc... How will the air make it to the ridge vent????  
    
    By locating your holes at the upper end of each rafter you will allow 
    air coming into the soffit vent of channel "a" to run up the channel 
    till it reaches the hip rafter, it will then enter the holes and move 
    to channel "b", to "c", and to "d" till it eventually reaches the ridge.
    
    By locating your holes as close as possible to the hip ends of each
    rafter you will create a better air flow then by simply drilling holes
    along the whole length of each rafter affected.  Is this more clear???
    
    Fra                     
    

I can see one basic problem with your picture (and assumptions?).  It looks like
you are expecting a ridge vent be installed.  I have a slate roof.  I do not
have any desire to try to put a ridge vent in this roof.  Are you saying that
without the ridge vent I cannot insulate the ceiling of my attic?

Somehow I must be missing something here.  With sufficient air flow going up the
bays, I would expect the air to constantly be going in and out within the 
propa-vent spaces.  I realize I am not a meteorologist, but it would seem that 
as long as the air can get in and the space is not extremely small, it would
be sufficiently vented.

I do not with to make this discussion rehash old news.  But, a ridge vent
cannot be an absolute requirement.

Ed..

re .20:

>I do not with to make this discussion rehash old news.  But, a ridge vent
>cannot be an absolute requirement.

The requirement is to allow air to enter the space at the lower edge of the roof
(usually the eaves) and allow it to leave at the upper edge (usually a ridge
vent).  If you can figure out another way for the air to exit, fine.

With a slate roof, I guess one of the reasons for ventilation probably does
not apply.  Prevention of heat buildup in the summer sun that reduces the
life of asphalt shingles.

-Mike

> Are you saying that
> without the ridge vent I cannot insulate the ceiling of my attic?

That's about the size of it.

Without both ends of the air space vented, you will get no significant air
flow.  On a large scale, think of opening a single window in the summer - not
a whole lot of ventilation goes on, even though you have a whole room full of
space for the air to circulate.  Open another window on the other side of the
house, though, and you get a cross-breeze, going in one window and out the 
other.

With the Propa-vents, you have a space that is 15 feet long, 12 inches wide
and only 1 inch deep.  It's slanted upward, and open at the bottom.  The air
in it is warmed, making it want to rise.  But there's nowhere to go, so it
all just stays there.  Trust us - that space just won't ventilate.

The main reason for ventilation is to allow any moisture that does get through
the vapor barrier to dissipate harmlessly.  It may still be possible to 
insulate your attic, but you'll have to look at super-duper industrial strength
vapor barriers.  You need to ensure that NO water gets into that space, 
because it can't get out.

Paul

    RE: .20
    
    If you have only one end of a propa vent open on the soffit end
    (the lower end toward the eaves), then I don't think you will have
    sufficient ventilation.  The air between the roof sheathing and the
    propa vent would be more or less stagnant.  You have to open both ends
    to get air *FLOW*.
    
    -al

    
    While YOU may expect the air to be constantly going in and out within
    the propa-vents, this is not going to happen. To get any kind of air
    flow, you'll need an opening in each end, cool air in, warm air out. 
    How you figure to get any air movement in your bays is beyond me...
    
    If a ridge vent is totally out of the question, a persons only
    alternative would be to have a ceiling below the ridge, with a gable 
    vent at each end... with a hip roof this is not possible.
    
    I can speak from experience, My grandfather has a big 2 decker in
    Fitchburg, with a slate roof and while it isn't a hip roof, it does
    have several gables.  Before the days of having to finish
    attics for additional living space, and the need of ridge vents, he
    decided to insulate the roof with foil-faced insulation.
    
    It may be interesting to note that he is a retired carpenter and was a
    General Contractor for many years before his retirement.  Knowing that 
    there was a need for ventilation, he drilled holes in his blocking
    leading to the eaves and also drilled out the ridge beam.  He had the
    house resided and they put in perfed soffits.  Two years ago he had to
    make very (read: exhorbitant) costly repairs to his roof because the
    lack of proper ventilation ruined his roof... the moisture had gotten
    to the roof (evidently through the seams) during the winters and 
    condensed on the cold roof, thereby rotting it out. You can do what you
    like regarding a ridge vent... it's your house.  
    
    With proper ventilation, any moisture that does escape through the
    vapor barrier will be carried out the ridge vent before it has time to
    condense.  And while propa vents do create a channel, they do not create
    an airflow...
    
    JMHO,  Fra
    

    
    There's a fairly new hip roof colonial down the street from us. The
    builder used sheet metal vents on the hip ends of the roof and a ridge
    vent for the rest. The ducts look a bit like a large dryer vent. But if
    you're against a ridge vent then these would probably be out, too.
    
    Good luck
    
    CdH
    

I am not actually against a ridge vent (or would it be ridge vents?).  My main 
concern is both cost and looks.  I had hoped to keep the cost as low as possible.

Am I correct in understanding that the shear size of the attic is what allows
the air movement?  Or is it the fact that for each eave, there is an eave on
the other side of the attic that allows the air to move from one side of the 
attic to the other side?

Also, what if instead of regular insulation, I put the insulation board.  The
ones that are like styrofoam?  Would I still have the same problem, because
the space between the insulation and the roof would allow moisture to condense?
I am suggesting not using the propa-vents.  Rather, just glue or nail or 
whatever, the insulation board between the rafters right onto the plywood (or
whatever wood the slates are installed onto.

I think, to answer my own question, that I would still have the problem of an
unheated roof, with just enough space between the insulation board and the
roof to allow rot.

Is there some kind of nice looking vent which could go into each hip that would
be somewhat less noticeable (or at least not look so bad)?  

Ed..

    Short of doing some serious reframing of the roof and adding a gable at
    each end of the ridge, I don't think you have to many other options...
    A ridge vent seems the way to go and is really not very noticeable, as
    well as being the least expensive option.  
    
    Most large homes with hip roofs have some form of a gable window which
    I would assume can be used for ventilation, but this is with all
    rafters and sheathing exposed... As soon as you close em up with
    insulation/drywall your negating them.
    
    have at it...
    
    Fra

	Re: .26

	Yes and no.  Having two openings does permit some airflow.  (The more
enclosed the space is between them, the more the airflow is restricted.)  A
major component of attic airflow, however, is having vents at different heights.
Heat rises since it is less dense air.  Most attics have both eave vents *and*
vents higher up so that the lighter hot air can flow out the "upper" vent and
be replaced by the outside air coming in the "lower" vent.  The intent is that
the temperature differential between the attic air and the outside air *alone*
will be enough to cause circulation to occur even if there is no breeze outside.
Having vents at only one height relies on the outside wind to try to exchange
the air.

	I suspect that using only eave vents -- even if all around the house --
to exchange air in such a restricted space as is being talked about in this
note will be fruitless.

								-craig

    When I went up to my attic, I felt like I was breathing in some real
    tiny particles and I felt like choking and had difficulty breathing.
    There are those pink rolls of fiberglass insulation up there. My
    question is, can that be loose fiberglass particles in the air, and if
    so, are they harmful? Or is it just dust in the attic?
    
    Or can there be asbesto dust up there? I didn't stay long to inspect.
    How can I check if there are asbesto material up there?
    
    I bought one of those 3M fiberglass insulation respirator. Is it safe
    to use it?

Yes, there can be and is fiberglas dust in the air.  Yes, it is harmful.  Best
to wear a respirator which claims to be effective against fiberglas dust.
(How can it be "not safe" to use a respirator?)

Also, wear loose-fitting long-sleeved clothing and gloves.

				Steve

When was your house built?  I haven't heard of asbestos being indescrimanantly
blown about in attics.  It was used in wrapping steam pipes, can be found in 
textured ceilings, some floorings,  and in joint compound as late as the 70s. 
In answer to your question, I doubt you have asbestos up there.  But no, most
respirators are of little use in protecting against asbestos.  You need a HEPA
filter as asbestos fibers are long and thin and pass through any other filter
like toothpicks through chicken wire. 

<(How can it be "not safe" to use a respirator?)
    
    
    I bought an industrial quality respirator from a Lab Safety catalog
    some time ago. My primary use was to be to protect myself against
    sawdust as a result of sanding.
    The catalog offers many different filters for the respirator. Each
    filter was effective for and ineffective against certain kinds of stuff
    in the air.
    
    Perhaps .0 had in mind some concern about false security?

I just installed some attic stairs to replace that hole in the closet.  The
next step is to put a floor down so I can make use of that now easily
accessible space!

That point about leaving a gap above the insulation is good to know.  But it's
not gonna leave me much headroom since my house is only 24' wide (I think a
standard 30 degree pitch) and I have 8" of rolled fiberglass running across the
top of the ceiling joists.  Having the floor start another 10-11" higher, I'll
be on my knees for sure. :-)

I wanted to put  a non-permanent floor down so I could still get at the
electrical wiring at a later date.  If  I cut the plywood to fit fairly snug
against the sides (roof rafters), an untacked-down floor shouldn't be a
problem, right?

If the plywood was to just sit on top of the joists I add, to what extent
should I support the upper joists (attach to the lower joists etc.)?  I imagine
I should throw some cross pieces in that sat on top of the lower joists and
kept the upper joists parallel and from falling over.  How close together
should such cross supports be?  Every 4'?  5'?  6'?  Should the upper joists
also be toe-nailed to the lower ones (or just to each other via the cross
members)?

                                                              _Mike

FYI -- a respirator that's good against asbestos isn't expensive.
I bought one for $20 at Spags.  I believe it's good for almost
any kind of dust I could come across.  That doesn't mean that it's
safe against gases (e.g. solvent odors, lead paint fumes, whatever).
But for dust, it should be fine.

	Enjoy,
	Larry

Don't leave the plywood completely loose -- buy a screwgun (under $20 for
the black&decker battery  operated one at various places) and put some
drywall screws into the edges.  Those'll be very easy to take out, and
they'll guarantee that the plywood doesn't shift that fraction of an inch
necessary to cause an edge to slip off a joist.  If that happens, and
someone steps on the now unsupported end of the plywood, the results could
resemble a Three Stooges movie!

I don't see any need for an air gap between the plywood and the insulation
-- *if* you can make a good vapor barrier underneath the attic insulation.
After all, your wall insulation touches the outside wall of your house.
A couple of layers of oil based paint are supposed to provide a good
vapor barrier.  

Putting crosswise joists on top of your existing ones is a good idea,
though, if you are going to put in more insulation.  The spacing you
use depends on how bouncy you are willing to have your plywood attic
floor.  Talking through my hat here, I'd guess you'd want no more than
24" spacing with 3/4" plywood, or 16" spacing with 1/2" plywood.
Or have I misunderstood your last paragraph?

Another alternatrive might be to put insulation between the rafters,
instead of another layer in the floor (or maybe in addition to more
attic floor insulation).  That requires a ridge vent, though.  You
need to keep air flowing between insulation and the roof deck to avoid
cooking the shingles on those hot summer days, and to avoid ice dams
in the winter.

	Enjoy,
	Larry

    When we bought our house 1.5 years ago the house inspector said we
    needed more insulation in the roof, probably new shingles in a year
    from the looks of them (there as 27 years old as the house is), and
    a rindge (sp?) vent (or some kind of vent) since there is no ventilation 
    other than the soffit vents on the bottom of the roof front and back.
    
    Well I haven't gotten around to any of the 3 above.  I plan on DIYing
    all 3 when the $$$ allow it.  FYI this is a Ranch style with truss roof.
    
    Question is that most of the interior walls (of the outside walls)
    severely condensate, especially at the ceiling corners.
    
    My theory:  The warm air from the house escapes through the poorly 
    insulated ceilings where it cannot vent out.  This moist air hits the 
    cold air of the roof itself and causes the condensation.
    
    If I only do one now:
    Which would be the wiser start?  Do the insulation now and hope the
    condensation is slowed by this?  Or do the roof/vent now and heat the city 
    of Gardner with my poorly insulated ceilings?  Is this the cause as I
    suspect, of the condensation?  Or is it lack of insulation in the
    walls themselves? (BTW The house has aluminum siding 27 years old as
    the house is, and the inspector did say the walls are insulated from
    what he could tell at poking around all the outlet boxes.)
    
    Also if I do the insulation first:
           1.  Do I perpendicularly cross the existing insulation or lay
               it parallel?
           2.  Is un-faced the way to go or should I get kraft faced?  The
               current insulation is kraft faced on both sides _but_ the
               attic side easily tears to the light touch (read: seems very
               poor vapor barier)
           3.  If kraft faced: does the faced side go down towards the
               ceiling?
           4.  If not kraft faced: should I pull up the old insulation and
               put a vapor barier in under it?  Over it?
    
    Feedback greatly appreciated,
    Steve
    

    
    My house only has the sofit vents. But the house has 15" of insulation
    in the attic. There is no condinsation in the attic. I think your best
    bet would to add the insulation. Put to down perpendicular to the
    existing insulation. And DO NOT use kraft face. The kraft face should
    be on the inside of the house facing the warm part of the house. Never
    on the outside. If I were you, I'd add about 9". It really helps during
    those cold sinter nights.
    
    Mike

    RE: .72 & .73
    
    Mike, your house might have an adequate vapor barrier to prevent
    moisture from getting into the attic which is why you may not have
    a problem with condensation.
    
    On the other hand, Steve does have an existing condensation problem.
    Adding more insulation without proper ventilation wouldn't cut down
    on the condensation problem.  So I would definitely ventilate first
    before the addition of new insulation.  If you have a ranch with
    trusses, it might even be easier to install two gable vents rather
    than a ridge vent.
    
    -al

    My ranch was built about 30 years ago (close to same age as yours,
    .72), and has 1" insulation in the walls.  The insulation is some sort
    of mineral wool sandwiched between two layers of black paper.  Any idea
    whether I should be concerned whether this is asbestos?  Sorry, that's
    an aside...

    If you have similar insulation, there's an airspace of about 1 1/2" in
    your walls.  I don't know whether this would help to cause condensation
    in the corners.

    A previous owner had blanketed our attic with insulation.  Unfortunately,
    they ran the insulation close to the edges and blocked the soffit vents,
    making a bad condensation problem worse.  If you insulate close to the
    edges, get some styrofoam channels to keep the insulation away from the
    roof sheathing in the channels with soffit vents.  A building inspector
    told me that such things exist.

    A new roof, ridge vent, and potentially new sheathing are steadily
    climbing on my "to do" list too -- unfortunately they're not climbing
    because I'm crossing things off the top...

    
    OK, my cut at .72:
    
    1) It's "ridge" vent, a continuous vent that runs along the roof ridge
       and allows air to circulate in the soffit vents and out the ridge.
       Make this part of your re-roofing job, and use the new low-profile
       plastic type, which looks much better. Installation is described
       elsewhere in this conference.
    
    2) If I read your note correctly, the condensation you're talking
       about is *inside* the house, that is in the living space, not in the
       attic. Condensation in the attic would be caused by insufficient
       venting and/or lack of a vapor barrier. For condensation on the
       interior surface of walls and ceiling, I would check for the
       following:
    
       o  Severely inadequate insulation, resulting in abnormally cold
          surface (what happens on most people's window panes)
    
       o  High interior humidity (rare this time of year, unless
          you're running a "Home Improvement" style humidifier or you
          have a hot tub in the den [don't laugh -- I've seen both])
    
    3) when adding insulation to the attic:
    
       o  use "Propa-vents" to keep the soffit vents clear. "Propa-vent" is
          a brand name; they are available at fine building supply stores
          everywhere, very cheap; you only need them where the insulation
          would tend to press against the roof sheathing and block the
          air flow from a soffit vent (ie, not all the way up to the ridge);
          also described elsewhere in this conference
    
       o  use unfaced; if condensation is apparent in the attic, it may be
          easier and more cost-effective to use a vapor barrier paint on the
          ceilings than to replace the existing attic insulation;
          otherwise, I would rip out the old and start with *one* layer of
          kraft-faced (with the facing *always* toward the warmth),
          followed by unfaced layers as necessary
    
       o  if the existing insulation does not fill in to the top of the
          ceiling joists, you may want to consider adding a thin layer
          over it up to the top of the joists, then another layer across
          the joists.
    
    

re: 25.72 

>    Which would be the wiser start?  Do the insulation now and hope the
>    condensation is slowed by this?  Or do the roof/vent now and heat the city 
>    of Gardner with my poorly insulated ceilings?  ...

      I like the idea of putting gable vents in walls at the ends of the
      attic. If the roof doesn't leak, there is little reason to replace
      it,  and  gable vents will be MUCH easier (cheaper) than trying to
      add a ridge vent without re-roofing.
      
      As for what to do first?  Well, I'd opt for the gable vents as per
      the previous paragraph.  They are the cheapest  and  probably  the
      most cost effective of the three items.
      
      I'd  go  for  added insulation second.  It is probably less costly
      than re-roofing and it will pay for itself in heating and  cooling
      cost savings in a few years.
      
      That leaves the roof, and, as I said, as long as it doesn't leak I
      wouldn't invest in replacing it.
      
>    Also if I do the insulation first:
>           1.  Do I perpendicularly cross the existing insulation or lay
>               it parallel?
      
      Is  the existing insulation at least as thick as the bottom member
      of the trusses? If not, you need to add insulation parallel to the
      existing  to  bring it up to at least be even with the tops of the
      bottom truss members.
      
      After  you've  done  that,  or  if  it  already is that thick, run
      perpendicular. Run right across the bottom members of the trusses.
      Cut  and fit neatly and tightly around the vertical members of the
      trusses.  Be careful at the eves; don't block the sofit vents! You
      can  buy  Styrofoam  "poppa vents" (spelling?)  that attach to the
      underside of the roof sheathing between the  rafters  (trusses  in
      your case) to keep a space open for air flow.
      
>           2.  Is un-faced the way to go or should I get kraft faced?  The
>               current insulation is kraft faced on both sides _but_ the
>               attic side easily tears to the light touch (read: seems very
>               poor vapor barrier)
>           3.  If kraft faced: does the faced side go down towards the
>               ceiling?
>           4.  If not kraft faced: should I pull up the old insulation and
>               put a vapor barrier in under it?  Over it?
      
      Use unfaced, as per a previous reply.  A vapor barrier needs to be
      on the warm side of the existing insulation.  You may already have
      one. (In addition to the paper on the isulation, that is.) If not,
      I believe that it is possible to get ceiling paint that can  serve
      as  a vapor barrier on the room side of the ceiling.  Probably not
      as good as a poly  barrier,  but  *MUCH*  easier  to  retrofit  in
      existing construction.

      In  any case, do not add a vapor barrier, kraft or poly, on top of
      existing or new insulation.  I would at least slash the top  kraft
      paper on the existing insulation with a knife evey foot or so.  If
      it comes loose without too much problem, rip it  off  and  discard
      it.

re .75:

Somewhere in this file is a discussion of whether rock wool contains asbestos.
In that discussion, I mention that I called the EPA (or some such agency) and
asked.  The guy said that to the best of his knowledge, there's no asbestos
in rock wool.

    If the condensation occurs at the top of the walls near the wall
    ceiling junction, one possibility is that the insulation in the
    wall has sagged leaving the top effectively uninsulated.  The way
    to check is to place a thermometer against the wall at various
    positions up the wall and measure the surface temperature.  (A
    thermometer with a remote sensor is best).  If the temperature drops
    then this is the likely problem.  Note that the temperature will
    likely be lower anyway where the wall attaches to the studs and the
    wall header and floor plate.
    
    Stuart

    If the insulation has sagged, there are two courses of action ...
    
    	1) remove the siding and re-insulate (and install a good
    vapour barrier while you are about it) and then re-side.
    
    	2) drill holes in the top of the wall and blow in extra
    insulation (the equipment can be rented for diy and you can
    buy blowing wool) or you can contract out.
    
    

    RE: .74 
    
    Al,
    
    Good idea.  I'll put in a couple of Gable vents this weekend. 
    Shouldn't take more than 30 minutes (x DIY rule of 4x = 2 hours).
    (I like to estimate real low so I come out on time! ;-)
    Seems like you just cut a hole and pop/screw them in from what they
    look like.
    
    Since the roof doesn't leak (as far as I can tell) I'll just do the
    gable vents for now and see if that works.  And since they seem cheap
    enough I should be able to afford the insulation so I'll be checking 
    around for a sale on the "pink stuff".  Anyone have any hints to where the 
    best deals are?  I'm in Gardner Ma.  I think when I go to do the roof I'll 
    do the ridge vent while I'm at it (if the gable vents don't do the trick 
    entirely).
    
    RE: .76 WLDBIL::KILGORE
    
    > 2) If I read your note correctly, the condensation you're talking
    >       about is *inside* the house, that is in the living space, not in
    >       the attic. Condensation in the attic would be caused by insufficient
    
    In the living space is correct.
    
    >       venting and/or lack of a vapor barrier. For condensation on the
    >       interior surface of walls and ceiling, I would check for the
    >       following:
    >
    >       o  Severely inadequate insulation, resulting in abnormally cold
    >          surface (what happens on most people's window panes)
    
    The inside walls don't feel cold to the touch.  Of course that could be
    due to the heat being kept on at least 68 (if it weren't for my 6
    month old and my 2.5 year old I'd keep the heat lower than that.)
    
    >       o  High interior humidity (rare this time of year, unless
    
    The interior humidity seems fairly normal.  I don't use a humidifier yet
    there is no static on the rugs and our skin is very slightly dry.
    Seems normal.
    
    >          you're running a "Home Improvement" style humidifier or you
    >          have a hot tub in the den [don't laugh -- I've seen both])
    
    Although I'm a great fan of the show and Tim Allen I don't use his
    turbo techniques.  Although I feel an urge to put chrome side pipes on
    my lawn mower with glass-packs for mufflers. :-)
                       
    RE: Everybody else:
    
    The insulation is up to the top of the joists.  This is a real budget
    house though and(I don't know if this is common practice or not but)
    believe it or not the accoustic 1x1 ceiling tiles are attached directly
    to the joists.  Nothing else between the insulation and the living
    space but the 1/2 inch think ceiling tiles.  Good thing I never slipped
    of a joist when checking things out the few times I've been up there!
    
    If the gable vents, then the insulation doesn't slow/stop the
    condensation I'll have to check the wall insulation.  Don't really want
    to go so far as to rip the siding off though......
    
    should be interesing,
    (thanks all very much),
    Steve
    

    Gable vents aren't really attached to the siding of the house.
    Usually they are framed in with 2 x 4s and the vent is nailed to
    that.
    
    -al

Also, we experienced some leaking around the our gable vents when the wind was 
from the right direction.  You might want to include some silicon caulk in 
you plans.  It worked for me.  At least, keep a "weather" eye on them.

Stan

    As I see it one of your problems is that the insulation has paper on
    both sides.  As a previous writer mentioned, DEFINITELY, slit all the
    paper on the cold side(roof side), or remove it.  It sounds like the 
    moisture is getting caught in your insulation and cannot escape,
    thereby causing moisture to remain next to sheetrock.   Also, for what
    its worth- On the addition of my 32x34 addition to my 24x36 house, I
    was
    told by the Building Inspector to get rid of the existing gable vents.
    (I had already installed ridge vents on the main house, when it was re-
    roofed.  He stated that gable vents do not work, and if you have ridge
    vents they actually hinder the proper cross ventilation of the soffit
    and
    ridge vents.

    
    
    I had a really hot attic last winter, as the snow on the roof seemed to
    insulate it pretty well. I had a gable vent at just one end.
    
    So I added a gable vent to the other end, and voila ! No hot attic. No
    its freeeezing up there.
    
    So I stapled some plastic bags over the gable vents, they reduce the
    flow but don't stop it. And I get a much warmer family room underneath.
    
    Simon

re .85:

If your attic isn't living space, you should *want* its temperature to
mirror the outside temperature.  The insulation between the attic and
the living space should keep your expensive heat from heating the attic.

Exactly...

I have a contemporary cape which has soffit and ridge vents, as well as gable
end vents. There is no attic to speak of. I stained the house two summers ago 
and you wouldn't believe the flow of warm air coming out of the gable end vents.
Yes, the ridge vents were also working.

CdH

    
    being lazy, it was easier to staple bags over the vents than stick
    insulation in the attic. Yes, I need to add some insulation. But the
    attic temperature was around 30 degrees, and thats also not healthy.
    This way it is a bit more reasonable.
    
    You would not believe how much junk there is up there.....
    
    simon

Why isn't it healthy for your attic to be 30 degrees?

It's not a matter of what temperature your attic is, as much as why it's that
temperature.

Regardless of how much insulation you have, heat will rise from your living 
space to your attic.  All the insulation does is slow it down.

If your attic is warm, you need more insulation.

If you attic is cold you have good ventilation.

If you have poor insulation and good ventilation, then you have a cold attic
and a warmer town (at your expense!)

So if thats the case, and for whatever reason, you don't add insulation, you
can at least help by reducing ventilation.   That sounds like what Simon was
doing with the plastic bags.

Of course, adding insulation will probably give a far greater return in the long
run, but for the amount of energy it takes to staple up a plastic bag, the return
might be worth it!

Bob

Question:  Why not cut the attic ventilation to zero, thus saving the
maximum amount of heat?

Answer:  because of rot and other damage caused by condensation.  A house
is full of moisture -- plants, showers, just breathing.  If there's too
much water, it will condense on cool surfaes -- like the underside of 
your roof, and then runs down inside your walls.

So the bottom line is, you must have a significantly better vapor barrier
between your house and your attic than you have between your attic and
the outside air.  If you don't (and most houses don't have good vapor
barriers), you can have serious trouble a few years down the line -- and
rot inside walls is seldom found before the damage is really expensive to
repair.

	Enjoy,
	Larry

I forgot to mention, a warm attic when there is snow on the roof can
cause ice dams, which leaks water in under the shingles ==> more rot.

	Larry

    This looks like the right place to pose my question.......
    
    We have an attic space which is accessible through a door in an
    upstairs closet.  The attic space is actually above the front hall of
    the house.  The space is currently insulated with 6" batts between the
    joists and another row of 6" batts perpendicular to the joists.  Total
    of 12" insulation.
    
    I would like to put a floor in the attic space and use it for storage,
    but the question is how to do it?
    
    One alternative would be to build up from the existing joists and
    install a false floor above the insulation.  That way the existing
    insulation stays in place and everything is fine.  However, I had
    another idea which seemed a little simpler and possibly less expensive.
    I would appreciate some comments/suggestions about the concept.
    
    I thought that perhaps I could make a "sandwich" consisting of plywood
    on the outside and styrofoam insulation on the inside.  It would look
    something like this:
    
             XXXXXXXXXXXXX  <-- 3/8" plywood--would be the new "floor"
             OOOOOOOOOOOOO  <-- styrofoam insulation--2" thick ??
             xxxxxxxxxxxxx  <-- 1/4" plywood--would rest on the joists
                                              and protect the styrofoam
    
    My thought would be to lay the "sandwich" over all the existing
    insulation.  I realize that this would compress the top 6" batt, but it
    would also fill in any spaces that might otherwise be created if the
    top batts were removed.  Also, the 2" of styrofoam would provide a
    similar R value as the old 6" batts.
    
    Will this work?  Would it be easier/harder to do than building a new
    false floor?  Would the styrofoam create a new "vapor barrier" that
    would trap and hold moisture in the existing insulation?  
    (We already have a vapor barrier in the ceiling below the existing 
    insulation).
    
    Thanks in advance for your comments and suggestions,
    Chet
    

    First, can you get the 4X8 sheets into the attic, through the closet
    opening?
    
    Second, is the space going to be a normal living space or just storage?
    If storage, the idea sounds O.K. If not, then you should move the
    insulation to the roof from the floor.
    
    Marc H.

    Another question along the same lines:
    
    I have an attic crawl space that I want to use for 'dead' storage.  It
    has 12" of isulation.  Can I just lay 2x4s or plywood across the
    joists, covering the insulation some and still have the safe
    effect/efficiency?
    
    Thanks,
    Joyce

    >First, can you get the 4X8 sheets into the attic, through the closet
    >opening?
    
    Obviously a good question.  I *think* so, but haven't actually tried
    it.  I wanted to get opinions on the concept before I spent too much
    time (and effort) swinging a 4X8 sheet of plywood up the stairs and
    through the closet.
    
    
    >Second, is the space going to be a normal living space or just
    >storage?
    
    Storage only.
    
    Thanks for the comments.  Any other pros?  Cons?
    
    Chet

Won't all the fiberglass (the stuff above the joists and the stuff below the
joists) get compressed?  If so, there may be a bigger negative effect on the
R-value than you expect.

    I would just place the pieces of plywood/boards across the joists that
    you want to use for storage.  Compressing the fiberglass will cut down
    on the R value somewhat.  You also gain some R value from the boards 
    placed over the joists.  If you have 6" joists and compress 12" of 
    insulation into that space, you probably loose about 1/3 of the
    insulation R value and the pick up 1/3 of that again from the R value
    of the boards.  If the joists are larger then 6", say 8 or 10", you 
    probably won't loose as much.  
    
    I wouldn't go thru the expense and time to double sheet plywood and 
    insulate inbetween.
    
    

    re .98
    
    Your not going to pick up 6inches of R value from a board or plywood.
    More like R 1 or something like that I'm sure the info is in here
    someplace. If you compress 12 inches to 6 you'll probably end up
    instead of R30 around the low 20's. (More than the R19 of 5 1/2 inch
    insulation, but not as much as when it is properly uncompressed to 
    12 inches... as you stated)
    
    Jean

To insulate my old attic space, I ran a set of 2X6 rafters perpendicular
to the ceiling joists and insulated between.  I got a full 12" (R-30, i think)
and it made a *BIG* difference in winter and summer house temps.

The cost of the materials is well worth the payback in comfort levels, IMHO.


Chris

    >>To insulate my old attic space, I ran a set of 2X6 rafters
    >>perpendicular to the ceiling joists and insulated between.
    
    
    Excellent idea -- and simple, too.  After all, I've already got the
    isulation.  Now, why didn't I think of that?
    
    Chet

How did you attach the new lumber to the existing joists?

   Gary

If all you're doing is adding insulation, there's no need for additional
lumber - just lay the insulation crosswise across the joists.  This is
actually better than having cross-joists. 

			Steve

and with the cost of building lumber these days it could be quite expensive to
run the cross-joists....

re: .102

I used those steel angles that have a quarter-twist to allow one to  nail/screw
one joist perpendicular to another.  I used 1" drywalls screws because I didn't
want to pound against the joists and pop the ceiling screws all over the place.


Also, in my case, I wanted to be able to take up the flooring when we built up,
which we just did this past fall/winter.  I reused every bit of material
save for those angle thingys.


I put them on alternating sides of the perpendicular beam on every other ceiling
joist, fastening each with two screws at the top and bottom joists.  I made them
on 24" centers and filled the void with 6" insulation over which was 7/16"
waferboard as a floor.  Served us well as added storage in what would have been
useless space.  By the time a joist was fastened in this manner, it was sturdy
enough to not need cross bracing.


Chris

I was also going to suggest that you put down 2x6 joists between the
batts, perpendicular to the lower set.  I don't think you'd need very
many connections between the upper joists and the lower ones, perhaps just
one connection at each end.  It's an extablished technique (called a
"floating floor" to attaching the flooring to a separate set of support 
joists that are perpendicular to the lower set and not connected to them.
This is done to reduce noise conduction, FYI.  Of course, the plywood
flooring does need to be firmly attached to the perpendicular joists.

	Enjoy,
	Larry

    The original noter just wants to add some storage area to his insulated 
    attic, which now has approx R38 insulation . ( I believe 6" is R19)
    Why go through the time, expense, etc to do all these perfectly
    acceptable ideas, if only a portion of the area is going to be used. 
    Just lay some type of plywood, dimensional lumber, etc. across joists
    and go crazy.  
    
    I picked the loose 1/3 of R factor as a rough figure. loosing 1/3 of 
    R38 is approx R13 and 1/3 of that is R4 gain.  That is not much to
    worry about in my opinion for a given area.  You probably end up with
    a R29 or so end result.  Now if you are going to utilize the whole 
    attic for storage, then I would add perpendicular joists and insulate 
    them and cover with floating floor.
    

    I just bought a house and moved into it last week.  The style is a
    Cape/Gambrel, 2 floors with 2 bedrooms upstairs.  My problem is this:
    The upstairs is TOTALLY unbearably hot and I need to do something to
    fix it.  I'd rather try things other than Air conditioning.
    
    The stats are:  It has no soffet vents or gable vents.  And there is no
    insulation.  If I do these three things, will it make it cooler up
    there or will it still be unbearably hot.  Is there anything else I can
    do?  I don't know enough about soffet and gable vents and insulation to
    know how much a difference I will see once installed.
    
    Any help is appreciated.
    
    Michele

	Attic venting (soffet and/or gable) and insulation will both make a
	big difference in your upstairs temperature. A fan (whole house or
	even just an attic vent fan) will help further.

	(not to mention how much the insulation will help your heating
	bills, and how much proper venting will help extend the life of your
	roof)

	Roy

If there is no venting, you'll have more problems than just a hot house!
Your roof will self-destruct in short order.

The best thing to do is to add a ridge vent along with adequate soffit vents.
(Forget gable vents, they're about useless.)  Also add as much insulation
to the floor as you can - R35 or higher.

				Steve

    re -.1
    
    insulation to what floor?  The two bedrooms are the attic so I would be
    insulating the walls surrounding the rooms.  I have access to one side
    of the roof, but will need to cut an access hole to access the other
    side.  Am I misundering your suggestion or did you think that the attic
    was above the 2 bedrooms?
    
    thanks....
    
    michele

I misunderstood.  Ok, you have a finished attic.  Yes, you should insulate
the walls (and the "ceiling"), making sure you don't block air flow from the
(to be installed) soffit vents to the peak.  This is usually accomplished with
polystyrene foam channels called "Propa-vents". I would recommend foil-backed
insulation to serve as a radiant barrier for this application.

			Steve

    related issue...
    
    I have a large attic, well insulated, with soffet and ridge vents.
    
    In the hot weather we've been having recently, I have often wished 
    there was a fan up there to remove the hot air, especially in the 
    evenings, to allow the second floor of the house to cool down more
    quickly.
    
    Now if it had gable vents, this would be easy. I'd mount a fan against
    the vent at one end, and let it suck the hot air out, drawing cooler
    air in at the other end. But how do I mount the fan for soffet/ridge
    vents?  Horizontal, drawing air upwards, yes. But unlike a fan on a
    gable vent, which could be boxed in so that all the air it moves is
    going straight out and not circulating around to be moved again, I
    can't see how to do the equivalent for the ridge. I imagined a row of
    small fans all the way along the ridge, all boxed in, but that doesn't
    seem to be the right way to do it.
    
    Any ideas?
    
    Thanks,
    
    Richard.
    
    ps...not interested in a whole-house fan, just something for the attic.

Well, you could mount a fan to blow air into the attic from the outside.  
If you mount the fan low, e.g. attic floor level in the middle of a gable 
wall, then I would think that it would be mostly blowing warmer air out.

	Enjoy,

    
    Home depot has some 1600 cft/p/m roof mounted fans for $57 - thermostat
    & fire prevention built in.  They're the dome type that mounts on
    the roof.

    >                  <<< Note 25.115 by SMURF::WALTERS >>>
>                                 -< roof fan >-
>    Home depot has some 1600 cft/p/m roof mounted fans for $57 - thermostat
>    & fire prevention built in.  They're the dome type that mounts on
>    the roof.
    
    I originally had an attic with no soffet or ridge vents, only gable
    vents. I did have the roof-mounted fan with thermostat and fire-fuse, but
    the attic and house seemed to always be too hot. Basically, the fan ran all
    summer and rested all winter.
    
    I then had the roof re-shingled, soffet and ridge vents installed, and
    the roof fan removed. But I put a large whole-house fan in the attic
    floor. When I run this, it sucks all cool air from outside, through the
    1st floor open windows, up through the house into the attic, and just
    forces all the hot air in the attic out through all the vents (gable,
    soffit, and ridge). It cools the house very quickly.
    
    Peter

    I'd like to have insulation blown into the attic.  I don't want to do
    it myself as there are three finished rooms, and hardwood floors.  Can
    anyone recommend a contractor (I've looked in 2000) in the greater
    Worcester area?
    
    Thanks
    

    I'm insulating a completely un-insulated attic, and have conflicting
    reports regarding vapor barriers. HQ told me that the 'latest word' 
    was that attics should use un-faced insulation to let the house
    breathe. Home Depot told me that I should get faced insulation. I
    noticed, however, that Home Depot did not carry unfaced. 
    
    Another customer (who looked like a professional carpenter) said that you
    could just slit the kraft paper with a knife to get it to breathe. But,
    he may have been refering to the adding of insulation to an existing
    layer.
    
    My question is this...is there new evidence out there that says attic
    insulation should have no vapor barrier at all, or should I get the
    kraft faced stuff?
    
    Thanks,
    Matt

    
    This doesn't address your main question, but I recently bought
    some from HD in Nashua, where they had both the faced and the unfaced.
    For some reason (which they could not explain) the faced was priced
    lower.  Same R value, thickness and length.
    
    So whatever you decide, check the prices - the faced may still be
    cheaper at HD.  Personally, I'd go for a vapour barrier.
    
    Colin
    

    
    
    I just went through this recently and collected quite a bit of info 
    from various magazines and insulation manufacturers. The common line
    is that everything I have recommends vapor barrier in the attic, faced
    side down.
    
    The only arguments I saw were about insulating the basement ceiling. 
    Some said paper down, some said paper up, some said no paper.
    
    								- Mac
    

A vapor barrier is required; not having one can lead to a rotted roof, not
to mention condensation damage to your ceilings and higher fuel bills.

Home Depot certainly sells unfaced insulation; I've bought tons of it there.
R25 attic blankets are the most popular form.

If the attic is currently uninsulated, you'd be better off to lay down
polyethelene plastic, tucked into each joist space, and then put down
unfaced batts.  You can use faced batts, but they're less effective, especially
if you just lay them loose in the joist spaces.

				Steve

I have never heard such alot of bologna!  

There are ONLY 2 times you don't use a vapour barrier in attic insulation 
(on the inside face) 

1) where it is being used in a climate where most of the year you have 
to cool with air conditioning AND humidity is normally very high

2) where you are adding additional insulation ... so that you don't create 
two vapour barriers, or if there is no existing vapour barrier, that this
barrier would have less than 2/3 of the R value to the cold side.
(e.g. if there is existing R12 with no existing vapour barrier, to add
a layer of insulation with an intact vapour barrier, the new layer of
insulation must have an R value greater than 24 ... viz ...


	- - - - - - - - -	New Insulation
				(must have R value > 2*n to use faced
				fibreglass or new barrier here)
	- - - - - - - - -				   v
	-----------------	New vapour barrier (or new insul facing)
	- - - - - - - - -
			 	Old Insulation (R Value = n)
	- - - - - - - - -
	_________________	Ceiling without vapour barrier


Stuart

    reply to .118

    You need the  vapor barrier to help prevent moisture condensation in the
    Fiberglas. Once it gets wet the R-value drops off and can't recover, it 
    relies on the air pockets, which get compacted. This problem will always 
    be there with Fiberglas batts. Dow-Corning (sp?) should have an 800 number 
    to consult with the experts, if your still undecided. 
    1-800-THinK-PINK (just kidding!)  

    /Jim

    Vapor barrier it is!!!!!
    
    A few quick questions about polyethylene.
    
    1) HQ and HD have only faced R30 (at the same price)...so should I still
       use poly AND the faced insulation?
    
    2) If so, how should I specify the polyethylene when I go to buy it?
    
    3) How far up the joist should I go with it?
    
    4) Should I staple it into the joists?
    
    Thanks again,
    Matt
                                                           

Use whichever form of the insulation is cheapest.  If you use faced insulation
with poly, slash the facing.

As for the poly itself, the kind they sell along with tarps, etc., is fine.
It should go all the way down into the joist area and be in contact with the
ceiling; you don't want any air gaps.   No need to staple it in, though that
might make it easier to work with.  The idea is to have as unbroken a barrier
as possible.

			Steve

>    1) HQ and HD have only faced R30 (at the same price)...so should I still
>       use poly AND the faced insulation?

Should be no problem if it is in direct contact, but then, I'd be inclined to
slash the facing across every couple feet in length.

>    2) If so, how should I specify the polyethylene when I go to buy it?

I dunno how poly is specified in the US, but in Canada, you would use 8mil
poly.  6 and 8 mil are construction poly weights.

>    3) How far up the joist should I go with it?

Depends on how deep you are going to make the insulation.  If you are going
to put at least R20 over the top of the joists, then I'd go with complete
lengths folded right over the joists, such that the joists are in the "warm
space".  If you are going with less insulation, a couple inches up the joist
should be fine if you caulk/seal.  If you don't, go to the top of the joist.
     
>    4) Should I staple it into the joists?

Yes, but I would take 20 year acrylic caulk, OR better if you can stand using
the stuff, acoustical sealanct (it is SO gooey and gets on everything and 
everything else too!) and seal the barrier to the joist at the seam.  Similarly
seal all barrier joins ... allow several inch overlap.  staple through the
seal.

While you are about it ... where all the walls meet the ceiling, make sure
any crack along the top is sealed if it doesn't occur under a joist.  Seal
all holes where wires come through the ceiling, and seal the poly to the wires.
Get some of the preformed electrical box seal for ceining fixtures, or form
them yourself with poly.  Special things must be done with recessed fittings
to seal them -- see an electrical dealer with the type of fitting, or an
insulation specialist ...  codes vary as to how to seal these fittings.

Ensure that the ends of the vapour barrier are sealed to the joists if you
lay over the joists ... so the rest of the joist is "outside".


			|
		+-------------------------
		+-------------------------
	End of		|Seal along end to ceiling/plate and to the joist
	Joist		|
		   Vapour Barrier

Stuart

RE: .126  (Also thanks .125)
    
>Ensure that the ends of the vapour barrier are sealed to the joists if you
>lay over the joists ... so the rest of the joist is "outside".
>
>
>			|
>		+-------------------------
>		+-------------------------
>	End of		|Seal along end to ceiling/plate and to the joist
>	Joist		|
>		   Vapour Barrier

Stuart,

In this 'sketch', is the end of the joist the part that sits on the bearing
wall? And does the end of the vapor barrier seal where the drywall from the
ceiling meets the wall below?

Thanks,
Matt
    

>In this 'sketch', is the end of the joist the part that sits on the bearing
>wall? And does the end of the vapor barrier seal where the drywall from the
>ceiling meets the wall below?


The end of the joist, depending on your particular construction, is over
the outer wall plate, or even past it.  Try to get it to end on the outer
wall plate.  (ie just past where drywall corners meet). I had a house where, 
due to the low roof pitch, I couldn't get to the wall plate if I were a 
rabbit, the space was SO tight in there!

Stuart

    We bought a new house last spring and there was no vapor barrier
    between the upstairs ceiling and the attic.  The builder and the home
    inspector both said that this was OK because of the amount of
    ventilation in the attic.  The builder was Cyril Lunn and the home
    inspector was Paul Maida.  I can't say that this note  has left me with
    a good feeling about this but I guess there isn't much to do about it
    now.
    
    							John

    re: .129
    
    I wouldn't spend any time worrying about it.  As long as there is
    reasonable ventilation in the attic and you don't run a greenhouse
    business downstairs you shouldn't have a problem. 

    RE: .128
    
    Stuart,
    
    I went into the attic last night a imagined the magnitude of work it
    would take to do it properly (whew!). It is a hip roof, and the corners
    will be a nightmare. 
    
    So, do you know of any way to spray-apply a good vapor barrier?
    
    Thanks,
    Matt
                                                     

    I've seen paint advertised as add on vapor barrier. This would mean the 
    ceilings below would all need a fresh coat of paint. I not sure here but, 
    I think the sealant is a primer coat and you may need a finish coat over 
    it. Anyone out there with some first hand experience which this type of
    product, maybe a manufacturer and product name?  

    
    re 132
    
    I believe that it's ordinary oil-based aluminum primer.  It has a
    low perm rate, about 95% for 3 coats, 88% for 2.   
    
    Another method is to use EPS batts that are available precut to press-fit
    snugly between the joists.   The EPS provides insulation and a vapour
    barrier in one. Higher cost, lower R vaue by thickness, but faster to
    install.
    
    Colin
                                                       

Glidden makes a vapor barrier paint.

	    How about that poly coated insulation that Corning came out with?
	It might work as a vapor barrier(?) but is advertised as being easier/
	less irritating to install.  
					Tim

    re: .135
    
    Nope - the stuff has holes in the poly so it won't act as a vapor
    barrier.
    

Indeed - Corning explicitly points out that the poly-wrap does not serve
as a vapor barrier.

				Steve

> I dunno how poly is specified in the US, but in Canada, you would use 8mil
> poly.  6 and 8 mil are construction poly weights.

	How about 4 mil?  I just used 4 mil on a wall and am
	hoping that it is sufficient ......

    
    Sure, unless you have such a high volume of air
    trying to blow thru your wall that poly might rip....
    
    jd

4 mil is considered a little light ... since, believe it or not poly is
air and vapour permeable ... just.  However, it has to be infinitely better
than no barrier at all.

Stuart

    B I N primer is really a white pigmented shellac that is used as a
    vapor barrier also. Beware of the fumes, though. It costs about $18 a
    gallon in most stores. I've used it since I ran into the same problem
    as the past respondent---the builder pulled a fast one and left no poly
    for the top floor's ceiling. 
    
    Mike

	8" of attic insulation (probably loose-fill cellulose, from the
	sound of it) isn't terrible bad. In fiberglass that would be about
	R-25. I don't know what it is with cellulose.

	As for the chilly feeling, the first thing you should do is
	determine why it feels chilly. Is it actually colder up there, or
	does it just *feel* cold? A thermometer will tell you that easily
	enough. If it's reasonably warm, but still feels chilly, then you've
	probably got drafts that make it feel colder than it is. 

	If you have draftiness, then a major probable culprit is the door on
	the attic stairs (there *is* a door, isn't there?). This entryway
	should be treated like any other exterior door, since it's going to
	an unheated area. The door should be sufficiently insulated and
	weatherstripped; otherwise you'll lose a LOT of heat and get drafts. 

	Also, the stairs should be insulated from underneath. If the door
	and stairs aren't insulated, you might as well have a hole in your
	ceiling.

	One option, instead of opening up the ceiling to get at the bottom
	of the attic stairs, would be to put a door at the top of the
	stairs. This would give you an "airlock" in the stairway, which
	would provide some level of insulation. The upper door could be
	heavily insulated, too.

	Roy

8" of cellulose is a bit better than R-25, if installed properly.  Of course,
more doesn't hurt; at this point you'd want to use fiberglass batts rolled
perpendicular to the joists.  The new Owens-Corning PinkPlus plastic-wrapped
batts make this much easier.

I agree that drafts are probably more responsible for a chilly feeling.

				Steve

This is what was done for our attic steps:

Foam insulation attached to inside of door with duct tape.
Insulation blown into wall next to steps.
Insulation blown into steps (holes were cut in the risers).
Door sweep.

    One quickie to see if your insulation is good enough: After the light 
    snow today, go check to see if it melts off the roof quickly. If you 
    are losing heat to the attic, the snow will melt.
    
    This is all assuming that you didn't have a snow base up there before
    this 'storm'.
    
    HUGE icicles are also a telltale sign that you're loosing heat out the 
    roof.
    
    8" should keep you out of immediate financial and ice trouble although 
    4 more inches laid perpendicular to the joists as noted earlier would 
    be mint. For now, I'd focus on the stairway situation...but I'm no
    help there.
    
    Congrats on the new house! 
    

    
    The extra insulation will improve the energy efficiency of the
    house, but don't expect to feel the difference.  Curing drafts is
    more effective for that.  I just added 6" of glass wool insulation
    to the attic, which already had about 8" of loose fill.
    
    My windows are really poor, even with full storm windows, so I've found
    that using the window insulation kits has been particularly effective
    in the bedrooms.  My wife also made insulated roman blinds for the
    kiddies room, magnetically sealed to the frame.  The blinds worked out
    to be about $20 a window, and are extremely effective.
    
    Also, note that FHA always tends to deliver more heat to the lower
    floors. If you want to even this out a bit, there should be control
    baffles in the ducts (you'll see little levers on the side of a duct) 
    these can be used to reduce the amount of air going to the ground floor
    registers, increasing the amount fed to upper floor registers.
    
    Even with the baffles, registers that are furthest from the furnace
    often have a hard time delivering enough heat.  You can improve this
    with a booster fan that goes insude the duct, or a puller fan that
    replaces a floor/ceiling register.  The latter is easiest to install.
    
    Doing this also makes the heating system a little less efficient,
    because the furnace fan works harder.  So another way to do it is to
    install ceiling fan over the stairwell to disperse the warm air more
    evenly throughout the house.
    
    Regards,
    
    Colin
    
    
    

>>>	I agree that drafts are probably more responsible for a chilly feeling.

	How can one detect a source of draft? Other than by moving a bare hand 
	around the edges of doors and windows, feeling for a cold spot, which
	is what I did, and came up empty. 

>>>	8" of attic insulation (probably loose-fill cellulose, from the
>>>	sound of it) isn't terrible bad. 

	I was wrong. After double-checking, it looks like 6" joists, and thus
	6" of insulation. And it doesn't look like its spread very well. 
    
	Anyone know where there's an insulation sale?

>>>	If you have draftiness, then a major probable culprit is the door on
>>>	the attic stairs (there *is* a door, isn't there?). 

	Yes. Its a six-panel pine. But it has rubber weatherstripping, a 
	rubber sweep, and a wooden threshhold. I checked it carefully, and 
	there is no -detectable- draft. 

>>>	Also, the stairs should be insulated from underneath. If the door
>>>	and stairs aren't insulated, you might as well have a hole in your
>>>	ceiling.

	Since the attic right now is unused, I think I'll lay insullation 
	on top of the attic stairs until the weather turns warm. 

>>>	One option, instead of opening up the ceiling to get at the bottom
>>>	of the attic stairs, would be to put a door at the top of the
>>	stairs.

	Hmm. Or lay over it a piece of plywood, with insulation on top
	of it. That might hold me over until spring. 

>>>    One quickie to see if your insulation is good enough: After the light 
>>>    snow today, go check to see if it melts off the roof quickly. 
>>>    HUGE icicles are also a telltale sign that you're loosing heat out the 
>>>    roof.

	Good ideas! This is why I came here. :-)
    
	Kevin     

    If installing a door at the top of the stairs is impractical, you might
    also look at buying some rigid insulation - 2 inch would do - and
    building a cover for the stairwell - easy to hook up a make-shift
    drawbridge to raise and lower it from the bottom. THAT should help a
    lot.

>>	I agree that drafts are probably more responsible for a chilly feeling.
>
>	How can one detect a source of draft? Other than by moving a bare hand 
>	around the edges of doors and windows, feeling for a cold spot, which
>	is what I did, and came up empty. 

I isolated the location of a couple drafts in a room by using a candle and 
watching the flame for movement.

Dan

    
    If you have a draft coming from the door, you might want to
    place some plastic over the door if it dosnt look to bad..
    
    JD

    
    Check your outlets - quite a bit of cold air infiltration through them.
    Can be fixed with gaskets sold by Frost King, and plugging unused
    sockets with child-proofing safety covers.

    
    Your big problem might not be the insulation at all.  FHA systems
    rely on a balanced flow of warm air through the living spaces and
    back to the cold air return.  There ought to be some duct controls
    in the system on various branches.  When I noticed an upstairs-
    downstairs temp difference this year I adjusted my system to
    put more heat into the cold spaces and less into the warm ones.
    And a lot less heat into some areas that are used for storage only.
    Worked for me - check it out.

        RE: .148	
 
>>>     Anyone know where there's an insulation sale?


        HQ in Shrewsbury has a sale on thru the end Jan. I bought 16" wide
        R30 batts for $20.82 a bag (covers 58.67 sqft). Home Depot across
        the street had the EXACT same price, but also charged for delivery
        where HQ was free within a 15 mile radius.

        Make sure you get unfaced insulation since you don't want a vapor
        barrier in the middle of your pile. This is discussed ad nauseum
        in earlier replies to this note. 

        Go with unfaced R19 (maybe R25 if cost is not an issue ;-)

>>> Your big problem might not be the insulation at all.  FHA systems ...

    I know. I'm worried about the FHA system too. That's why I'm looking
    for ways to determine which is causing my problems. I'll probably write
    another note on this soon - I didn't want to discuss it under this
    topic. 
    
    Anyway, what I need is to discover which is/are my problem(s). 

>>> >>>     Anyone know where there's an insulation sale?
>>> HQ in Shrewsbury has a sale on thru the end Jan.  I bought 16" wide
>>> R30 batts for $20.82 a bag (covers 58.67 sqft).

    Thanks! (Is that a good price?)

    Also, keep the draft-determination things coming. I probably won't get 
    around to trying them all for a few days yet.

    Kevin 

    Some prices from Home Depot. I would say they are good, but I'm not much 
    of a price watcher, and I didn't have time to shop around on my insulation 
    project. Home Depot charges for delivery ($25).
    
                       15" width              23" width
                   ------------------      -------------------
    R19 unfaced     48.96 sqft $9.79        75.07 sqft $15.00
    
    R25 unfaced     22.50 sqft $5.85        34.50 sqft $8.91
    
    I think these are good through the end of January.      /Matt
             

    Ditto on .149's suggestion.  Make a cover for the stairwell out
    of foam insulation.  If you don't need to go up there very often,
    just lay the stuff across the stairwell opening and don't worry
    about hinging it or anything.

    Houses lose a lot of heat via the "stack effect" -- warm air rises
    within the walls and vents into the attic if the tops of the walls
    are not sealed.  It takes a very careful builder to worry about that.
    So if you are up in your attic adding insulation, it's a good idea
    to also try to seal any air leakes from the lower floors into the
    attic -- both leaks from the living spaces and leaks from the walls,
    even the outside walls.
    
    		Enjoy,
    		Larry

    I've read all these notes and there's one thing I don't understand --
    why does everyone say to slash the facing on faced insulation or
    to get unfaced insulation? 
    
    Our attic was filled with vermiculite (loose dusty stuff) and a few
    bits of fiberglass here and there.  We've just removed all the
    vermiculite and all the odd bits of fiberglass.  Our next step
    is to lay down plastic to create a vapor barrier.
    
    Now, do we get faced or unfaced fiberglass?  It seems to me that
    unfaced makes sense since we'll have the plastic as a vapor barrier.
    But let's say the faced stuff turns out to be cheaper. Why can't
    we just lay it down intact, facing side down? What is the purpose
    of removing or slashing the facing?
    
    Thanks,
    Ingrid

    The issue is that you never want to have two vapor barriers in the
    same space, as this can lead to condensation between them.
    
    				Steve

But if the two vapor barriers are next to each other, what's the harm?
There's no insulation in between to get wet (nor is there a significant
amount of air to contain vapor).

    
    Perhaps if you lay kraft-faced over poly the paper will be sandwiched
    between the poly and the bitumen coating.  The paper could get damp,
    mildew, and get chomped on by cellulose-eating bugs.  
    
    Colin

    Thanks for the explanation on why you might want to slash the
    facing if you put down a plastic vapor barrier.
    
    Now here's another question.  I went to the bookstore during lunch to
    see if they had anything on proper installation of insulation.
    (They agree with you folks who recommend slashing by the way!)
    
    One thing they all seem to recommend is that if you lay down plastic,
    it should not go up and over the floor joists.  Instead, they say
    you should lay a piece of plastic in each bay and staple it at about
    1" up the joist.  But none of them mentioned why you shouldn't just go
    up and over the joists?  Anyone care to venture a guess?  It seems
    to me that you'd have a more complete vapor barrier if you placed
    one contiguous sheet across the floor (up, over, and down the
    joists and across each bay.
    

        I am about to reinsulate my attic as well.  It seems that when they
        built my house about 40 or so years ago that they liked to use
        aluminum foil paper faced insulation.  I assume this has a vapor
        barrier.  The whole think is onyl 1/2 an inch thick.  So...Do I:
    
        1) Just place the unfaced 6" insulation over the previous
           insulation.  It might be a bit bumpy but it will fit.
    
        2) Remove the old insulation, (YEECH!) and put put down a new
           vapor barrier as mentioned in the previous message.
    
    
        The first option is the most appealing to me, but is it safe to use
        old insulation for the vapor barrier if it already has one there?
    
        BTW:  I would think that if you ran the vapor barrier over the wood
              that the vapor would be trapped on the would and do more
    damage.
    
        thanks
    ~
    -jon
    

I think this has all been covered earlier in this topic.  My recollection is
that by running the plastic over the joists you open yourself up to rotting
of the joists.

				Steve

Re: .164

Just put the new unfaced insulation over the old.  No need to take up the
old stuff.

				Steve

    re: .165
    
    If it was covered earlier in the topic, sorry, I must have missed
    it even though I've read all the replies.
    
    Anyway, what you say makes sense.  The books I looked at seemed
    to suggest problems with mildew but didn't come right out and
    say, "Do not lay one contiguous piece of plastic or X will happen."
    
    Thanks mucho for the help.
    
    Ingrid

    I just did my attic.  It too was built 40 years ago and I think there
    was all of 3 inches at the most up there.  I just put unfaced on top of
    what was there.  I have to say there is a BIG difference in the time
    the house now holds heat.  
    
    One thing I didn't do is what corning suggests and that is to now put
    another layer of R19 running the opposite way.  Maybe next year. 
    
    Mark
    

    My house had 3 1/2" when I moved in - it was built in 1972.  I put
    another 6" of unfaced insulation on top of that, which pretty much
    filled up the areas between the joists.  A couple of years later, I put
    another 6" in at right angles to that (and put in soffit vents which
    the house should have had but didn't).  Really cut the heating bills
    down to size!  It is actually easier to buy at least the unfaced
    insulation in batts (8' long pieces rolled up together) instead of
    rolls like I did - I spent a miserable weekend day both times crawling
    around up there with shears, cutting the rolls to fit, in my long pants
    and long shirt and gloves and mask, and there is still no way to avoid
    ending up all itchy.  So when we did my neighbor's place, we used the
    batts.  His house is bigger than mine is and is just exactly three
    batts wide, so we only had to cut pieces to get around the plumbing
    vent pipe, the attic access, and such stuff - went a lot faster, and
    lot less itchy!
    
    /Charlotte

Why are you putting down plastic...faced is cheaper than unfaced plus 
plastic and very easy to install...come to think of it, why are you putting 
faced in the attic at all?  Just use unfaced batts.

But since we are on the plasic discussion, I can't imagine that laying 
plastic over the joists would be a big problem.  The faced edging get 
doubled over each joist so why would plastic be any different, not to 
mention being a royal pain to install between each joist.

    Well we dropped the idea of laying down plastic.  An older book
    my husband looked at recommended this.  But, since looking at
    newer books it appears that faced bats is the way to go.
    
    We are using faced bats because the house inspector recommended
    we add a vapor barrier when he inspected our home.  It seems 
    that most books recommend it too.

    
    For faced insulation, the flanges of the facing should really be
    stapled to the joists preventing airgaps, rather that simply laid down
    between them. This is only easy to do when the ceiling is not installed
    but takes time, which is why most builders opt for poly.  It's
    impossible to staple the flange when you are retrofitting faced
    insulation. So if you want a continuous vapour barrier, you have to
    either cover the joists or staple panels between the joists.
    
    A couple of books that I read recently mentioned that you can spray-paint
    on a vapour barrier using oil-based aluminum paint, which is an
    interesting notion.  
    
    C
    

    I've read that you can get a pretty good vapor barrier with multiple
    coats of ordinary paint.  Plastic is better, of course, but nothing
    makes a perfect vapor barrier, not even plastic.  The most important
    thing is to make it easier for moisture to get OUT of the attic than
    to get INTO it.
    
    I've also read that the big heat loss into the attic (after putting
    in reasonable insulation) comes from air flowing up through the
    walls and into the attic.  This "stack effect" occurs because the
    air near the inside surface of the walls heats up and rises into
    the attic and away, pulling in cold air from the cellar.
    
    So while you are installing insulation in your attic, it's a good 
    idea to try to seal off the tops of the walls, including holes for 
    electrical wires, pipes, etc.
    
    	Enjoy,
    	Larry

In my house I have access to the back sides of some of the bedroom walls from an
unheated "attic" space.  These walls typically have 6" fiberglas batts stuck
between the studs: most of these batts are loose and have gaps around them, as
seen from the attic space.

What I would like to do is install some rigid insulation on the backs of these
walls to better insulate them.  However, I don't want to install rigid
insulation that contains a vapor barrier, thus introducing one where it
shouldn't be.  

What rigid insulation can I use in this application?  Certainly the foil-covered
isocyanurate boards are out.  There is a compressed fiberglas rigid insulation
product which I presume allows water vapor to pass through, but this stuff is
not easy to get (ie, the Home Depot type stores don't carry it).  What about the
other foam-type rigid insulations, styrofoam, etc.  Do these pass water vapor
through?

Any other suggestions?

-Chris

    The extruded styrofoam is definitely a vapor barrier.  The white
    slightly crumbly "beadboard" (like coffe cups) is a remote
    possibility, but I think even that is probably a vapor barrier.
    
    I think you best bet is to fix up the fiberglass - or put the
    foam behind the fiberglass - and then put some wood sheathing
    or possibly screening over that to hold it in place.

    
    Possibly not a do it yourself, but blown in fiberglass insulation
    seems like a good match to the problem.
    

    re -.1 actually I've seen places like Grossmans offer blow in  
    machines for rent so It may be DIY
    
          Dean

That's for cellulose.

>     re -.1 actually I've seen places like Grossmans offer blow in  
>     machines for rent so It may be DIY

	if as .-1 said those are for the cellulose (ie. "nature guard"
	product), why rent one when I believe Home Depot told me they
	let you "borrow" theirs for free when you buy the bags of
	nature guard there....

Same thing at Grossman's I believe.

       My basement is unfinished with the insulation visible in the
    ceiling.  I would like to put up some plastic sheeting over it but was
    concerned about creating another vapor barrier (the insulation has the
    facing up against the floor boards, as it should).  Can I use standard 
    plastic sheeting, normally used for a vapor barrier, and poke small
    holes in it?  The handyman section of this Sunday's Globe mentioned
    another material called Tyvek (sp?) that is supposed to allow vapor to
    pass though, but not air.  Has anyone used this?
    
    Tom

You can certainly use Tyvek.  It's expensive for this purpose.  Plastic that
is slashed in places will do as well and is much cheaper.

				Steve

    Another option is to use the weed guard sheeting that you put down in
    flower beds.  This will allow air to circulate through the insulation
    to keep mositure from being trapped.
    
    Doug

    More insulation questions!
    
    Over this past summer I have insulated the basement, insulated the
    attick and now I'm at a loss as to what to do with the crawl spaces I
    have.  The house is a 40 year old Gabrel Cape. I have two bedrooms and a 
    full bath upstairs.  There is a crawl space on both sides of each 
    bedroom.  When you open this up you are looking at the roof line and to 
    your right and left are the backsides of the bedroom walls.  
    
    There is penty of room to move around in this area so it won't be bad
    to insulate.  I just don't know what to insulate.  
    
    What should be insulated?  The roof?, the walls, both?
    
    Any suggestions would be greatly appreciated.
    
    Thanks,
    
    Mark
    
    

I've been this route.  Insulate the walls and floors which are adjacent to
living space.  Don't insulate the roof.  (If you want, you can do what I
did and put a radiant barrier on the roof side, but open at top and bottom
to allow air flow.)  Make sure air can flow up into the attic and escape
through whatever vents you have.

			Steve

    Well what I have right now is both the walls and the roof insulated. 
    This is in most of the upstairs.  Do I need to remove the stuff on the
    roof?
    
    Also the floor is plywood.  Would it be worth putting holes in the
    floor and blowing in insulation?  
    
    What is a radiant barrier?
    
    Thanks,
    
    Mark
    

Is the crawl space heated?  If yes, then keep the roof insulation.  If no,
take it down - it will contribute to roof rot and/or ice damage (depending
on your climate).  You want the roof to be as close to the outside 
temperature as possible.  There should also be soffit vents to allow air
to come up and rise up through the attic (are the air channels to the
attic open?)

A radiant barrier is a reflective foil which, when installed on a side of
the roof which gets sun, reflects heat back out through the roof and keeps
the house cooler in summer.  It can also serve to keep internally generated
heat from escaping through the roof in winter.  Your site is in Marlboro,
so I assume you live in MA or nearby.  Radiant barriers aren't popular in
the north, though I do think they have some value.  I put some up in my
similar "crawl space" because the roof there faces due south.

It sounds as if someone thought that insulating the roof was the right thing
to do.  It would be if you intended that as living space, though it risks
damaging the roof.  If it were me, I'd take down the roof insulation, make
sure that outside air can come in through vents and escape through the
attic, and insulate floors and inside walls.

					Steve

    I want to get this right.  What I have right now is the roof insulated
    and the back side of the room wall insulated.  The crawl space in not
    heated.  
    
    So I take the insulation off the roof line, and make sure the walls are
    well unsulated.  The walls (2x4 construction) are insulated.  What I
    thought I would do is add that hardboard foam stuff over that.  That
    would be good right?  So when I open up that door it should be as cold
    as outside in there, right?  Just like the attic.  
    
    Now, I have vents on either end of the house up in the attic.  There
    aren't any ridge vents because there isn't a ridge really.  The way the
    gambrel is there isn't any room for them.  My dad has them (he has a
    ranch).
    
    Where the inside wall meets the ceiling joists should I make sure there
    room through that so it can vent up into the attic?  How can I check to
    make sure it's getting enough air?  Will it have frost on the inside if
    it isn't breathing properly?
    
    This house is 40 years old and it all looks dry and clean but I have
    been insulating and I don't want to cause troubles.  I have a feeling
    when I insulated the attic that I blocked some of the airflow from the
    crawl space up into the attic.  I have to check and see if that is the
    case.  If I did I'm going to take some of those styrofoam things and
    push them up through it to give it air.
    
    I just had my roof redone.  It was stripped right down to the bare
    wood and it looks great but like I said.  I have really started
    insulating and I don't want to cause problems.
    
    Mark
      

If you add foam panels you might create a second vapor barrier, which you
don't want.

Can you see up into the attic where the inside wall meets the roof?  If not,
you should make sure air can travel up there.  What I did was insert
"those styrofoam things" against the roof line, plug up the bottom of the 
remaining space with some fiberglass insulation and then pump cellulose 
insulation into the rest (from the top). I also have soffit vents at the 
bottom of the roof opening into the crawl space - do you?  You should.

What it sounds like is that at present your crawl space is shut off from the
outside on top and bottom.  This is an invitation to ice dams and roof rot.

					Steve

    Home Quarters now sells plastic vents. Less likely to break 
    than the styrofoam ones.
    
    Steve
    (the other)

At Home Depot as well.  I used the plastic vents for my cathedral and they 
were a breeze to install and no mess.  There were more expensive but well 
worht it from my perspective.

    Definately insulate beneath the floor of the crawl space.
    
    But why take down the roof insulation?  IF (a big if) there is a gap
    for air to flow from the soffit vents to the ridge, between the roof
    deck and the insulation, then that should be ok, yes?  If there isn't
    enough airflow there to keep the roof deck at outdoor temperatures,
    then you've got problems.
    
    	Regards,
    	Larry

I went up in the attic last night to look around - hoping to find nothing.  The
good news is that there appears to be no water anywhere.  But I did find
something rather disturbing.  The insulation company used those cheap styrofoam
vents.  After installing them, it appears that they jammed the insulation in
towards the soffit, causing the vent to collapse.  On one side of the house,
about 1/3 of them were completely shut off and on the front side of the house,
all but one was pinched off so much it's a wonder that any air got through.
I started the task of pulling the insulation back, installing new vents (the
plastic ones seem a bit sturdier) and reinstalling the insulation.

Next time you're up there, try taking a flashlight and shining it down a few
random vents to see if they're open.

While I'm here, is it an overkill to use 6.5" over existing 9.5" or should I go
with 3.5"?  Does 3.5" come without a VB - I don't remember ever seeing it?

Chris

Go with the R25 batts.  They're cheap enough that it would probably cost more
to use R13 unfaced, if you could find it.  That plastic-wrapped stuff is
great.

					Steve

    I extracted every note about insulation in this conference and read
    them at home last PM, but I'm looking for opinions on my particular
    situation.
    
    A few years back, I had cellulose blown into my walk-up attic floor.
    It's an 1837 antique colonial with no other insulation (yet). I wish I
    had used more foreseight, but I didn't. The problem is that I now want
    to turn this huge (soon-to-be-heated) attic into a playroom for the
    kids and am about to have the roof insulated to this end.
    
    Thus far, I've only spoken with one contractor who wants to do the
    following:
    
      1. Apply fiberglass batts in kneewall areas (walls adjacent to 
         attic living space) and plug up where rafters meet crawl space.
      2. Drill 2" holes in plastered ceiling and blow cellulose down each
         rafter. He says he packs more tightly than others so very little
         settling..
      3. Add soffit vents.
    
    The house already has a ridge vent running the length of the attic
    (40'). The one contractor I've spoken with thus far says the cellulose
    will breathe enough such that adding soffit vents (and no propa-vents
    between rafters) will be sufficient ventilation-wise. I'll install a
    programmable thermostat so we'll, in general, only have the heat on at
    certain hours of the day.
    
    My questions:
    
      1. Any concerns out there re: 1.5' or so of cellulose in the floor
         and then an additional 1' or so in the roof?
      2. Do I need propa-vents? Again, he says no. If I were to install
         them, how would one install something like this with a finished
         attic ceiling?
    
    I have another contractor coming in this weekend. The first contractor
    says he provides a transferable certificate of guarantee for all of his
    work and says that if there are ever moisture problems as the result of
    the insulation, he would pay for the repairs (guaranteed in writing).
    He's certified, insured, has been in business since the '70s, and has
    no BBB complaints filed against him.
    
    The sentiments about vapor barriers and ventilation in this file are
    well-documented. Still, most of the notes I read spoke about these
    issues in the context of fiberglass and not blown-in cellulose.
    
    For what it's worth, the first guy quoted me $660 for the installation
    of fiberglass batts, blown-in cellulose, and soffit vent installation.
    He cleans up after himself, but doesn't do any of the finish work (only
    plugs the 2" holes in the ceiling with styrofoam circles; I have much
    touch-up of the plaster to do anyway before painting, so not a biggie.]
    
    Opinions welcome/encouraged.
    Thanks in advance.
    Bill Cummins

    Feedback from Larry Seiler..
    
From:	WRKSYS::SEILER       "Larry Seiler, x223-0588" 13-MAR-1997 13:44:21.71
To:	MAY30::CUMMINS
CC:	SEILER
Subj:	RE: Noticed you are/were quite active in this note string.. Any opinions here? Thanks in advance.. BC

Hello,

I don't see any problem with having insulation *under* the playroom floor.
It's even useful (a little):  first, because you aren't going to heat the
playroom all the time and second because it should help reduce sound
transfer.  You'll probably still hear things that bang into the floor, 
but given that it's a playroom, that may be a good thing.

Now, about your contractor's plans:

      1. Apply fiberglass batts in kneewall areas (walls adjacent to 
         attic living space) and plug up where rafters meet crawl space.

Fiberglass batts in the kneewalls sound fine, except that you really
want more than just 4" of fiberglass if you can get it.  That's all the
kneewalls in my house have, unfortunately.

      2. Drill 2" holes in plastered ceiling and blow cellulose down each
         rafter. He says he packs more tightly than others so very little
         settling..

I gather from this that the contractor intends to completely fill the 
space between the dormer ceiling and the roof deck with insulation.
That's called a "hot roof" design, as opposed to a "cold roof" design, 
which depends on venting to keep the temperature under the roof deck
similar to the outside air temperature.  Insulating right under the roof
deck can cause very high roof temperatures during the summer, which can
be a problem for shingle life, so I've read.  More seriously, there can
be serious condensation problems if the vapor barrier has gaps.

I've read a lot of arguments on this subject in the "Journal of Light
Construction" -- a nifty magazine for light construction professionals.
A lot of contractors present "hot roof" designs for cathedral ceilings
and argue that they'll work just find if installed carefully.  Others
point out that you really want a design that works fine even if *not*
installed carefully, or even if the vapor barrier loses effectiveness
over the years.  After reading all of this, I'm inclined to go with
venting whenever I can, and only think of a "hot roof" design if there 
is no practical way to provide venting.


      3. Add soffit vents.

It beats me why he's putting in soffit vents if he isn't going to have
a clear air path up to a ridge vent.  Soffit vents work because air
gets pulled through them into the attic.  Wind blowing across the ridge
vent can cause this suction, or it can be caused by the chimney effect
as warmer attic air escapes out a ridge vent or through vents in the
end walls of the attic (ridge vents are far more effective).  

    The house already has a ridge vent running the length of the attic
    (40'). The one contractor I've spoken with thus far says the
    cellulose will breathe enough such that adding soffit vents (and no
    propa-vents between rafters) will be sufficient ventilation-wise.

I don't believe there will be much air movement through the cellulose,
especially if it is packed tight.  That's one of the advantages of
cellulose insulation: it is better than fiberglass at impeding air
movement.  Even fiberglass, which is a lot looser than cellulose, is
considered to impede air movement too much if it is right up against the
roof deck.  To look at it another way, standard tables say to provide
*twice* the area of vent openings if you simply put a *screen* in front
of the vent holes, because the screen impedes air movement.  There's no
way you are going to get any worthwhile venting through several feet of
packed cellulose.


Regarding your question of how to install propavents behind a finished
attic ceiling, I suggest that you consider two approaches:

  a)  Remove the ceiling and do a proper "cold roof" design with venting.
      This may also allow you to install the new ceiling lower, in case
      you don't have enough space for sufficient insulation.  That is
      usually the case for dormer ceilings, if they are attached directly
      to the rafters.

  b)  Find an insulation contractor who understands air venting and
      who will either provide sufficient venting for a cold roof
      design or else will design a hot roof solution that doesn't 
      require venting.  A lot of people use hot roof insulation systems, 
      so this may be your best bet -- especially since there probably
      isn't room to lower the ceiling.


	Enjoy,
	Larry

PS:  Feel free to post this to Home-Work if you like.  I don't read 
the notes file very often since it was "reorganized".  LS