Conference 7.286::home_work

the name of the company that sells it escapes me. but
its sold by the foot (4' wide) at state lumber.
and the company will send you all the info you want 
call
1 800 add foil

        Your pardon.  I guess I should have included that in
        my original note...  EAGLE SHIELD  is the company I
        bought mine from.  I know there are others selling
        radiant barriers, but don't have a lot of information
        about them.  (i.e. Sears comes installed for ~$1.69
        a square foot -- OUCH!)
        
        Eagle Shield also guarantees that their product will pay
        for itself out of savings in 3 years or less and has a
        financing plan that doesn't require a down payment (with
        good credit.)
        

        I learned tonight that Ray Robbins, the National Training
        Director for Eagle Shield will be in Boston this Friday
        night to talk about the Eagle Shield radiant barrier. 
        
        He'll be at the Howard Johnsons in Newton (the one
        over the Mass Pike) Friday evening, speaking at 7:30
        and again Saturday at 10:00 AM.
        
        If anyone is interested in going, please let me know
        (mail to DELNI::PERKINS) and we can get a group together.

RE: my earlier reply
the name of the company is reflectix.  and it sells for $.50/sq ft.
$.45/sq ft in quantity

    Does this radiant barrier have an R-rating associated with it?

>    Does this radiant barrier have an R-rating associated with it?
        
        No.  R-ratings are associated with conductive insulation.
        R = Resistance to the passage of heat through the material.
        
        Radiant barriers reflect radiant heat (the heat given off
        or radiated by an object.)  Thus they don't have R values.
        
        I do seem to remember that one of the things I read said
        that some sort of computer model was done to calculate the
        "effective" <what ever that means> R value of a radiant barrier
        and it was in the 30s somewhere.  I didn't pay much attention
        to it, though since the disclaimers for the study were longer
        than the explanation of what they did.

Reflectix has R-15 when properly installed

        How is the R-value for Reflectix determined?  or is
        this product a combination product (standard insulation
        and a radiant barrier?)
        
        Do you have some?  Can you describe it for us?
        

re: .10
reflectix has r-15 by itself when installed properly (needs airspace 
on reflecting side).

I have described it in detail elsewhere in this file - (look in the 
insulation notes - lots of good stuff already there)

but the net to my node is real slow the last day or two - haven't had
the time to go searching for it, maybe someone else closer to JOET 
might....

I called Owens-Corning a while back to see how much R-value one could add by
using Reflectix on top of the regular insulation.  I was told the R-value would
be around 1 or less!  As described elsewhere, you need multiple inches on either
side of the reflectix to be effective.

-mark

RE .13:  It is easy to understand why Owens-Corning would not be eager 
         to say anything nice about radiant barriers -- after all they
         are the largest manufacturer of fiber glass insulation  :^)

         Also, their information about it having an R-factor of 1 is 
         a long way out of date.  It is true that almost any metal
         touching a solid surface has an R-factor of 1.  This is why 
         O-C's foil faced insulation has so little radiant efficiency. 
         In order to be effective as a radiant barrier, a double
         barrier sandwich is necessary.

RE: .11: 
         It is the technology that is the same, not the gradient.
         The technology works the same way both in space and in 
         homes.  This is more than implied, it has been tested
         and proved.
         
         Tests were conducted by several reputable agencies and the
         test data and results public domain and available for your
         personal evaluation.  (eg. The Oak Ridge Federal Lab test
         facility determined that radiant barriers on top of R-19
         insulation resulted in a 39% reduction in heat transfer
         which equates to a 17% reduction in electrical consumption.)
         
         There is a direct comparison on a cost/benefit basis.  There
         isn't one on an R-value basis - because the 2 types of
         insulation aren't dealing with the same type of heat loss.
         (What is the radiant reflective factor of fiber glass
         insulation?) This radiant barrier reflects 93% of the radiant
         heat that strikes it.
         
         It appears that Eagle Shield, Inc. believes that money is
         important.  Consider their guarantee that the product will
         pay for itself out of what is saved in energy costs in 3
         years or less.  That is a pretty strong statement of financial
         consideration on their part.  It the product doesn't work,
         they eat it!
         
         I looked at the data and the guarantee and the test data
         and decided to try it.  I don't see that I have anything
         to lose.  If it doesn't work, I get my money back.  If it
         does, I get to keep my money -- and the radiant barrier.
         
         Rather than look askance, I invite you to look at the data.
         You might also consider addressing your questions to the
         company representative when he is in town tomorrow night.
         I know I have questions I plan to ask.

<     Reflectix has R-15 when properly installed

   I am not sure of the exact structure used, but the R value is the equivallent
fiberglass insullation need to maintain the same temperature gradient using 
equal energy(i.e.  What is the R-value of fiberglass insulation needed to 
maintain a 70f>100f temperature gradient with X BTU cooling?  WHere X is the 
ammount of energy used to maintain a 70F>100F temperature gradient with a 
radiant heat barrier.)  "Your mileage may vary" is very appropriate, because
the effectivness of radiant heat barriers is effected more by proper vs.
improper installation then anyother insulation.
 
>     What is proper installation?

   Radiant heat barriers must have an airspace on BOTH sides.  Fiberglass 
insulation for most purpose is an airspace because its biggest component is 
air pockets.  

   There must not be a short circuit path around the barrier.  For flat 
applications the "house side" is usually sealed.  

   The heat must be drawn away, if not the heat that is reflected can build 
up increasing the gradient and decreasing the efficiency.  A well vented attic 
is usually sufficient.

>   What are good applications?

   Installed between roof rafters.  Install between each rafter from the 
soffit vents to just below the ridge vent.  Must have good soffit vents between
EACH rafter.  Eventhough there is an opening between hot and cold airspaces at 
the top, the "Chimney effect" prevents a short circuit.

   Over attic insulation.  Some experts recommend using wire spacers a few 
inches above the insulation to improve the airspace.  The important part about 
the insulation is to seal the "house side" from the outside at the ends and 
seams.

Brian

Reflectix is also an excellent vapor barrier, I was warned not to use 
it over fiberglass as it might keep the fiberglass moist

RE: .15
        Your summaries are accurate, Ralph.
        
     1. The Eagle Shield radiant barrier is guaranteed to pay
        for itself (when properly installed) in 3 years or
        less.  < I believe this is for attic installations. >
        
        The guarantee is held and administered by an independent
        company NESA (National Energy Specialist Association),
        which "...administers several different national limited
        warranty and guarantee programs for the benefit of
        purchasers of products and services of participating
        NESA Members."
        
     2. It is not a vapor barrier.
        
        For side wall installations, an air gap is necessary
        between the radiant barrier and the outside siding.
        < 1/4" strapping is suggested >  The fiber glass
        insulation in the wall forms the house side air barrier.
        
     3. The most efficient place to install it is in the attic
        over the existing insulation -- where the major heat
        loss (and gain in the summer) is.
        
        A total seal is not necessary, however the installation
        instructions say to overlap the runs 2-4 inches, and
        staple around access places and fans.
        

        
        
RE .16  

>  There must not be a short circuit path around the barrier.  For flat 
>applications the "house side" is usually sealed.  
        
        I'm not sure about this.  Granted, large "holes" would
        reduce the effectiveness of the barrier -- as it would
        with any form of insulation.
        
        Other than the instructions to over lap the edges of
        the radiant barrier, (and not cover open light fixtures)
        The installation instructions said nothing about sealing
        the run edges.  It seems to me that attempting to do
        this would increase the installation labor costs
        incredibly, with little additional benefit.
        
        Can you explain what you mean by 'short circuit path
        around the barrier' if you mean something other than
        ways that (convective) heat could flow around it?

>   The heat must be drawn away, if not the heat that is reflected can build 
>up increasing the gradient and decreasing the efficiency.  A well vented attic 
>is usually sufficient.
        
        I guess I don't understand what you are saying here,
        either.  How does reflected heat increase the gradient?
        (Doesn't it decrease it?  Isn't this what makes a radiant
         barrier work?)
        
        In the winter, we want the heat to reflect back into the
        living space.  In the summer, we want the heat to be
        reflected away from the living space.  In horizontal
        applications, the reflected heat gets conducted out
        through the attic ventilation ports by the convective
        air currents.
        
        When the radiant barrier is installed over the fiberglass
        insulation in the rafters, your explanation of the need
        for soffit vents between each rafter is accurate. What I
        don't understand is what you are meaning about forming or
        preventing a 'short circuit,' however.  I am obviously
        missing something...
        
        Also I have seen nothing about sealing 'the "house side"
        from the outside at the ends of the seams' in the
        installation instructions.  This seems to be the same
        issue as sealing the seams of each 4 ft running length.
        
        The instructions do say to make sure the radiant barrier
        goes all the way to the wall at each end (being careful
        not to cover any soffit vents on the sides of the house.)

RE .18

>RE .16  

>> There must not be a short circuit path around the barrier.  For flat 
>>applications the "house side" is usually sealed.  
        .
	.
	.        
>        Can you explain what you mean by 'short circuit path
>        around the barrier' if you mean something other than
>        ways that (convective) heat could flow around it?

	The idea behind any insulation is to keep the house side closer to the 
desired temperature then the outside.  With large holes convective currents can 
flow around the barrier and negate and insulating capacity.

	I reread my original reply and it did sound overly complex and 
pessimistic.  In the right application, such as unused attics, radiant barriers
are better than additional insulation.  My original reply sounded like you 
had to go around with a caulk gun and smoke pencil and get every crack.  Not so,
when layed carefully and flat over fiberglass insulation, the fiberglass 
insulation is an adequate barrier against such convection currents.

	The one situation where I have not been convinced about the 
effectiveness of radiant barriers is for a partial coverage application(less 
than 1/2 the area).  

>>   The heat must be drawn away, if not the heat that is reflected can build 
>>up increasing the gradient and decreasing the efficiency.  A well vented attic 
>>is usually sufficient.
        
>        I guess I don't understand what you are saying here,
>        either.  How does reflected heat increase the gradient?
>        (Doesn't it decrease it?  Isn't this what makes a radiant
>         barrier work?)
 
Unfortunately, the heat that is reflected does not reradiate into space
(I am most familiar with cooling season examples), but is traped in the
attic or between the roof joists.  Therefore the temperature rises, unless
the excess heat is drawn off.  Long winded example available on request.

>       (doesn't it decrease it?  Isn't this what makes a radiant
>        barrier work?)          

Radiant heat barriers decrease the gradient between the inside of the house and 
the outside of normal insulation(cooling season).
 
>        In the winter, we want the heat to reflect back into the
>        living space.  In the summer, we want the heat to be
>        reflected away from the living space.  In horizontal
>        applications, the reflected heat gets conducted out
>        through the attic ventilation ports by the convective
>        air currents.
        
Agree, Agree and Agree.  I am originally from an area where cooling season
insulation is more important than summer(ARIdZONA).  In that application 
the rafter approach is preferred over the horizontal.

Brian 

        Ahhh... Thanks for the clarification.  I kept mixing
        winter and summer applications and was confusing myself.
        I can see that we are saying the same thing.
        
        As for the partial coverage issue.  I think we all
        will agree that the usefulness of any insulation product
        is only as good as the percentage of coverage.
        
        Likewise, if only 1/2 of the area is available to install
        insulation (or additional insulation) the value of
        installing it can only approach 1/2 (at best!)  On
        the other hand, adding insulation where you can will
        improve the comfort and result in some savings...
        "your mileage will vary" according to the applicability,
        coverage area, and other factors.  :^) A house with
        R-99 and a radiant barrier over 1/2 the area and no
        insulation over the cathedral ceiling will still be
        losing a *LOT* of heat. :^)  We need to be practical
        about where we invest our money and efforts, taking
        a serious look at the return on our investment.
        
>Radiant heat barriers decrease the gradient between the inside of the house and 
>the outside of normal insulation(cooling season).
        
        Cooling (summer) applications, is where radiant
        barriers are most effective.  This is because the barrier
        is installed on the outside of the insulation, reflecting
        the radiant heat back before it gets to the insulation
        (which acts like a heat trap keeping it in during the
        summer.)
        
        What this means is that a radiant barrier over the
        insulation with a properly vented area (soffit vents
        and hip cap for rafter installations;  attic vents
        for over the insulation in the "floor" of the attic)
        will keep the radiant heat from getting to the insulation,
        which maintains the gradient barrier between across
        the insulation (between the inside of the house and
        the radiant barrier.)
        
        This is another place where some people confuse radiant
        barriers with vapor barriers, thinking that they can
        have 1 product achieve both desires.
        
        If the radiant barrier is installed on the inside 
        of the insulation (living area side) your contention
        is true, it does reduce the gradient across the
        insulation. This is not a good idea!  
        
        Installed on the outside, however.  It prevents the
        radiant heat from getting to the insulation, maintaining
        the gradient.
        
        In fact it is in the southern areas of the country
        that radiant barriers are providing the greatest benefit,
        keeping the heat out!  Since most air conditioning
        is done with electricity, this is also where the greatest
        savings is to be had.
        
        It has only been recently that people have considered
        installing radiant barriers here in the northern climates.
        There are still considerable savings, but like the
        house with partial coverage, the degree of savings
        :^)   Ah only had t'cut 3 cords o' wud dis yeer. :^)
        is less -- but still there.
        
        

        Well, it was a very interesting meeting.  It turns
        out the information I had was incorrect.  Ray Robbins
        is the V.P of Marketing and Sales, not the Training
        director...
        
        What he turned out to be was very well versed in radiant
        barrier technology and usage!  After his 'friendly
        Texan' presentation he fielded questions from the audience
        and proceeded to teach us all a lot about radiant
        barriers.
        
        His response to a question about the "R" value of the
        Eagle Shield radiant barrier was "R doesn't stand for
        religious."  Then he proceeded to explain about R ratings
        and how they are derived.  The ES-rb has a calculated "R"
        of ~30.  This is because it is a double sided barrier with
        a thermal barrier/break between the foil sides. Earlier
        generation radiant barriers (and most of ES's competition)
        are single sided barriers which work less than 1/2 as well
        as a double sided barrier.  < This explain's the R-15
        claim for the Refletix in an earlier note and the
        difference in pricing. > 
        
        Ray also told us that the TVA (Tennessee Valley Authority)
        will be releasing the results of a recent test where they
        pumped 55% humidity into a test house with the ES-rb over
        the fiberglass for several months.  Apparently the results
        show that there was mold and mildew all over the inside of
        the house and condensation on the windows, but none above
        the ceiling, in the insulation or the area between the
        radiant barrier and the house.  < He's going to send me
        a copy of the test report when he receives it. > 
        
        On the subject of heat build up in the attic (summer), we
        were shown how the roofing would only build up to a
        certain temperature (based on the materials used) before
        it started radiating any further heat back out into the
        air currents.  The point was that the roof would reach a
        maximum temperature regardless of the presence of a
        radiant barrier and that this temperature was determined
        more by the building materials and the outside temperature
        than by the presence or lack of a radiant barrier.  The
        major reason for the radiant barrier is to keep the I-R
        radiant energy from heating up the insulation and thus
        the house. 
        
        When asked about new construction, he did tell us that
        ES has a non-perforated product that is designed for
        use as both a vapor barrier and radiant barrier.  He
        was quick to add that it worked best when it was installed
        with an air barrier on both sides -- which necessitated
        furring the wall board away from the rb 1/4 inch.
        
        There was more (including his own personal introduction
        to radiant barriers and Eagle Shield - which was pretty
        interesting) but I think just about all of it has already
        been covered in this note.  If anyone comes up with
        a question that hasn't been, I'll see if I remember
        what he had to say - or if it's in the information that
        I picked up.  (I'm still reading.)
        
        Bill

Re: .21

I've been trying to formulate a discreet way of asking you to make the
standard disclaimer of personal interest. I can't come up with one, so I
have to ask outright.  I mean no offense, but most of this note and the 
replies posted to others reads as hard-sell.

					>>>==>PStJTT

    Do you have a phone no. or address for Eagle Shield? I don't think
    one has been entered yet.
    

        I purchased my radiant barrier from Stu Fabric in Watertown
        926-7683.  Eagle Shield sells through local representatives.
        
        Eagle Shield is 1 of 60+ companies (including Sears) that
        sell a radiant barrier product.  Though the product(s) are
        all essentially the same (single/double barrier, punctured
        or not) the marketing/sales methods are different. Since the
        technology and radiant barriers has been around for over
        20 years, when I found out about its applicability to
        homes, I was surprised that I'd never heard about it
        -- and wasn't alone in my ignorance.
        
        Since I started looking, I've found that the major
        difference between the companies seems to be the degree to which
        they are interested in educating the consuming public.
        This was evidenced even more by the talks I attended over
        the weekend. Eagle Shield seems to be willing to educate
        people about this technology and is doing it through
        networking. (Friends telling friends - the same as we tell
        each other about contractors who do good work...) Yes,
        they get to sell their product that way, too and that
        seems to be a pretty fair exchange.  So far
        I've only found out about 2 other places where I can
        get information about radiant barriers (Sears and
        Reflectix.) I have asked for information from them, too.
        
        I agree with the networking philosophy and when I find out
        about something I think is good, I tell my friends about
        it -- and let them make up their own minds because they
        *ARE* my friends.  Indeed, I would still be ignorant about
        radiant barriers if it hadn't been for a friend's sharing
        information he'd found out about with me. < What have you
        learned by reading this topic? >  Likewise, I am quick to
        warn my friends about scams (like the airplane game) that
        I find out about. ?Hard sell?  not me, thanks. 
        
        Before I started this topic, I did do a search of the
        conference to see if there was more I could learn about it
        here, (though I didn't remember anything.)  When I didn't
        find more information about radiant barriers, I
        contributed what I had and was learning. 
        
        My intention in this note and others (Radiant barriers
        aren't the only topic I get 'wound up' about.) has been to
        be informative on a topic that I did not see already
        covered where I could contribute information and knowledge
        that I have. I have learned a lot by reading notes and
        find few opportunities to share what I know.  I'll
        throttle back -- and thanks for the feedback. 
        
        Bill 

>         Tests were conducted by several reputable agencies and the
>         test data and results public domain and available for your
>         personal evaluation.  (eg. The Oak Ridge Federal Lab test
>         facility determined that radiant barriers on top of R-19
>         insulation resulted in a 39% reduction in heat transfer
>         which equates to a 17% reduction in electrical consumption.)

Am I doing my R-math right?
Heat transfer reduced to 61% of what it was.
1 / 0.61 = effective R-value of 1.64.

> Am I doing my R-math right?

Nope.  First off, your math assumes the original R value was 1, where it is
in fact 19.  Second, it doesn't take into account the original R value.  The 
correct equation (I think) is:

R value		19 (original R value)
of radiant  =	---------------------	  - 19 (original R value)   =  R12
barrier	      .61 (relative heat transfer


Paul

        Not being all that familiar with calculating R-values, I have no
        idea what a correct formula might be. 
        
        My point is that R-value has nothing to do with radiant barriers.
        R-value is for conductive heat loss.  Radiant barriers deal with
        radiant heat loss (or gain.) 
        
        An example I saw (and will have to go looking for in all the
        literature I've been collecting...) that attempted to compare the 2
        was to measure the temperature of objects placed on either side of a
        radiant barrier and then do the same using standard mineral
        insulation, increasing the amount of insulation until the same
        temperature is reached on the "outside."  Then measure the
        insulation to determine the "equivalent" R-value.  I'll take
        a look and see if I can find this particular write up.
        
        As I said in an earlier note, there was also some sort of "computer
        model" done, but I didn't follow the math on that either. 
        
        <:^)  How do we determine the R-value of something that stops
        convective (air flow) heat loss?   <:^) 
        
        Bill

    I'm planning on finishing my basement and have a question! Does
    anyone have any information regarding vapor barriers?  I was told
    I should put up plastic before I put my studs up.  If this is the
    case, can anyone give me the lowdown?  thanks...

    
    	Normally the vapor barrier should be between the insulation and
    the wallboard. Also if you use insulation with a backing there is no
    need for the plastic vapor barrier. 
    

    This partly depends on your foundation now.  If there is a vapor
    barrier on the outside of the foundation, you should NOT put one inside. 
    In spite of the vapor barrier, the concrete will still pick up some
    moisture, and needs room to breathe (either on the inside or outside).
    If there's no barrier on the outside, I would think your best method
    for an inside vapor barrier would be the 'paint-ons' that they have. 
    They're more commonly used to stop leaks in foundation walls.
    Typically (on a regular living floor), the vapor barrier is over the
    studs and insulation, and is literally a huge piece of plastic going
    all through the inside of the exterior walls.  The construction would
    be, from the outside going in;
       
    Siding, plywood, studding (with insulation between studs), PLASTIC,
    plasterboard, your favorite wall covering.
    Our house was built like that almost 5 years ago, and we've never had a
    problem.  It also helps a lot for drafts - ie Wind speed can't
    penetrate the plastic.
    
    Whatever you do, you don't want to have anything trapped between 2
    vapor barriers, or it will just rot away on you.
    		GOOD LUCK!
    
                   Patty

    rep.1 -- You aren't supposed to use insulation with a backing inside a
    wall.  Any insulation that is going to be 'covered up' should only
    be insulation .... I believe the reason is that the paper poses a fire 
    hazard (but then it doesn't make sense that plastic is ok!)
    
    	at least that's 'the law' in N.H.!

    Have you tried looking at note 1111.11 BASEMENTS, 1111.59 INSULATION,
    or 1111.104 VENTILATION.  Each of the these notes lists all topics
    in the conference with these keywords.  
    
    1111.11 Basements discusses all phases of basement remodeling including
    insulation and varior barriors.
    
    1111.59 Insulation discusses installing insulation and varior barriors.
    
    1111.104 Ventilation discusses ventation problems.  Too much or
    the wrong kind of insulation can cause ventilation problems and
    needs to be considered.

    

    I question whether the law says you can't have paper on the insulation
    in walls.  After all, if I am not mistaken, all wall insulation comes
    faced and attic insulation generally comes unfaced.  I have very
    seldomly seen insulation in walls that did not have a paper facing on
    it.
    
    Ed..
    

    Maybe is was just NH law ..... all of our insulation was unfaced ...
    they said it was a fire code.  

This note has been temporarily write-locked pending approval of the author.

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Maybe everyone else knows all this, but it was new to me as of yesterday.

Type VTX PDCSTORE for access to information about available DEC (non-computer)
surplus goods.

Categories include bookcases, drafting equipment, ladders, shelving, stands,
cabinets, tables, tools, totes, workbenches.

Today they have a dozen workbenches, all at under $30, a Rockwell 1/2 inch chuck
3/4 horse drill press at $250, 8-drawer Proto tool chest $45, a 6X12 shed for 
$112.50.

I've never dealt with them, but their VTX set up is well organized and the
descriptions of goods seem complete and friendly.  

Everything has to be picked up by you (DEC badge in hand) in Contocook, NH.

The drill press is listed at $325, not $250 as the base note suggests. Was this
a mistake or is this item up for bid?

Even if it's a mint older Rockwell $325 is way high.

CdH
who goes to a lot of tool auctions

Transcriber error.  It was the pipe threader that was $250.

    Is there astore like this in Colorado????? There are a number of
    sites here in Colorado Springs, I'm sure there must be plenty of
    excess goodies here that DEC might want to sell.
    
    Denny
    

I believe stuff gets shipped to Contocook from all over, so Colorado surplus
probably ends up in NH.

And northern NH, at that.  Convenient from nowhere....

		Steve

    Out of curiosity, I checked-out some of the items listed in VTX
    PDCSTORE, and I was surprised at how much higher the prices are than I
    thought they'd be.  Several years ago when I worked at the ACO
    facility, the plant was going through an office furniture "facelift",
    and they offered ACO employees first crack at the stuff they were
    getting rid of.  I bought one of those older gray desks, which I
    consider `VG+' for $10, and a cloth chair, no rips, with armrests and
    wheels, also in `VG+' condition for $5.  I'm kicking myself still for
    not picking-up one of those beautiful drafting tables with a drafting
    machine for $25...
    
    Still, however, the prices seem good for what you're getting, but IMO,
    I think they're a little high.
    
    John
    

              <<< Note 4487.6 by SASE::SZABO "Number 7 rules!" >>>

>    I'm kicking myself still for
>    not picking-up one of those beautiful drafting tables with a drafting
>    machine for $25...
>    
>    Still, however, the prices seem good for what you're getting, but IMO,
>    I think they're a little high.
    
    I think the prices in the PDC store are now reasonable and competitive 
with prices you would pay at used office furniture stores, maybe lower. The 
old practice of selling stuff at ridiculous prices was a nice benefit but 
cost Digital big $$$ in the long run. As someone who once bought a 4 drawer 
lateral file for $25, it is a great deal. As a current 
stockholder/concerned employee, I gotta believe that Digital is absolutely 
correct in selling the stuff for it's real value rather than giveaway 
prices.

    What I find amazing in the PDC store listing is some of the unique 
stuff that I would never expect to see in the list. Vanities and granite 
blocks (maybe old surface plates) seem to be strange listings....

    	Vic H

Doesn't seem to be an existing discussion on this topic...

A relatively recent product introduction (in the northeast, anyway) has been
a radiant barrier product, specifically "Reflectix".  This is two layers
of polyethylene (I think) "bubble pack" with aluminized mylar foil sandwiched
between and around.  It comes in rolls (2 feet and 4 feet wide) and also in
a form designed to be stapled in between 16 inch-OC studs (as you would
insulation batts.)  Price is about $20 for a 2'x25' roll, with other sizes
proportional, though the 4' rolls are a bit less per sf.

Depending on how you use it, it can provide significant insulation all by
itself (manufacturer claims an R16 value when used under a crawl space), or
as strictly a radiant barrier, stapled to roof rafters, for instance.  In
the latter case, it doesn't insulate but keeps radiant energy from being
transmitted through the roof to the air space beneath.  In the south, radiant
barriers have been used to reduce cooling costs, and I think this would also
be worthwhile in the summer for the northeast.

The company which makes Reflectix also offers it in a "duct wrap" form (rolls
about 6 inches wide) and as pipe wrap sleeves.

I've seen it at Somerville Lumber, Grossman's and Builder's Square (Home
Depot doesn't seem to carry it.)

I am planning on using it two ways.  One, attached to my south-facing roof
rafters to keep the attic (and kneewall space, I have a Cape) from heating
up in the summer.  I also think it would help improve the air circulation from
the soffit vents to the ridge vent all year round (you are supposed to leave
a 3-inch gap, top and bottom, in this application).  I'm also looking at using
it to wrap a hot-water heating pipe that runs through an unheated kneewall
space (now that I'm insulating it; previously, it was soaking up heat from
the living area.)

I'd be interested in comments from folks who have used this product or
similar products.

				Steve

Steve,
	When I priced the stuff out last year I decided it wasn't all that
much more money to use foil backed polyisocyanurate to accomplish the same
purpose and then you do get insulation value as well.  I will attest that
too little attention is paid to reflecting heat in or out.  Last summer, my
attic was the coolest room in the house.  Relecting the heat back out made
a dramatic improvement.

    I remember reading an article a few years ago about aluminum foil (or
    something like that) coated roofing material.  This was put on over the
    rafters and the shingles were nailed to it.  It was supposed to help
    reflect heat off of the house.

I also looked at the reflectrix at Sommerville Lumber and concluded that
double foil faced polyisocyanurate was a far better insulator and would do
as good a job at reflecting heat.  HQ sells 1" thick in 4'x8' sheets for
$10 (about the same price per square foot as Reflextrix) and 1/2" sheets
for $5.  The insulating value is listed as R7.2 for 1" polyisocyanurate
or R3.8 for 1/2", plus about R2.8 per side that has a 3/4" air gap (and
somewhat more for larger air gaps, and more for horizontal spaces).

The Reflextrix is probably easier to apply in constrained spaces than
4'x8' sheets.  On the other hand, I've had good luck slicing up the
polyisocyanurate sheets with a utility knife to fit exactly into
whatever space is desired.  

A foil backed roofing material sounds very convenient.  


	Enjoy,
	Larry

    One use I had for Reflectix (or whatever it's called) was to line my
    1950's-style heat registers.  Those big, ugly jobbies that leave only
    sheathing and clapboard between me and the outside.  I couldn't take
    advantage of an airspace between the wall and the reflective surface,
    but I still could feel a perceptable difference when I put this stuff
    in.  A couple of snips with scissors, a fold here and there, jam it in
    place, and put the register cover back on.
    
    I felt it was worth it for that application.
    
    -- Kenny House

I've now put Reflectix up along the rafters in the largest kneewall space
in my house; time will tell if it makes any difference.  I see two advantages;
one is that it will channel air from the soffitt vents through the 
Permavents into the attic, and the other is that it will keep radiant heat
out of the kneewall space.   I'm also using it to wrap a FHW pipe which runs
through this space.

I don't know if my knees are ever going to recover from the past few weekends
spent crawling around this kneewall space and my attic, the latter not being
tall enough for me to even sit up anywhere in it.

					Steve

    There was adouble length segment on "Market Place", the Canadian
    Broadcasting Corp'n s conumer show on the use of reflective foils
    as an insulating material.
    
    They spent a lot of time and effort ... what they discovered was, that
    while it did reduce radiation, and would look like R16 to radiant
    energy, it was an extremely expensive form of insulation for cold
    climes because a very small proportion of heat lost from a house is
    due to radiation.  They estimated, that in Saskatchewan, with -40 C
    winters (for a couple months at a time), it would take well over 50
    years to pay for itself.
    
    Where foils really did come into their own was on foil backed gypsum
    board, where they acted as a radiant insulator, but also as a vapour
    barrier.  The infiltration through a metal foil is about a factor of
    100 less than through 4 mm of polyfilm!
    
    It your installation of the foil will reduce infiltration as well,
    then you'll see a bigger improvement than just as a radiant insulator.
    
    Stuart

Re: .6

I am not really using the product as insulation, nor as a vapor barrier 
(it's in the wrong place for the latter), but mainly as a radiant barrier.
I agree it is expensive, and if I had been able to find a simpler
radiant-barrier-only product, I would have used it.  I considered using
foil-backed foam as others have noted, but it would have been much more
difficult to install in my particular application.

In our climate, winters rarely dip below zero-F for any prolonged period
of time, and summers can be scorching, especially on our south-facing
roof.  One of the benefits I hope to acheive is that in the winter, the roof
will stay colder (when snow-covered) and I'll have less of an icicle problem,
which has been plaguing me this past winter.  The added insulation in the
floor and walls of the kneewall space, as well as better insulation around the
heating pipe, will probably help a lot.

				Steve