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Re: GSBN:Re: : slab edge insulation



I beg to differ with John and John. I did a fair amount of infrared camera work a number of years ago to see where heat exits a building in central California. We would crank the heating system up to a little bit above what one would normally heat a house to, and then film it from the outside in the middle of the night. The three greatest loss sites for a "normally" insulated house (one that just meets the minimum California requirements), were (1) the aluminum frames of windows, (2) the slab edge, and (3) hot water pipes and other pipes (e.g., the pop-off valve) near the water heater. Slab edges, when the slab is exposed to the night sky, account for a VERY significant portion of the winter heat losses. Slab edges, when they are tucked under a very wide eave, account for a lot less. And slab edges that are insulated, very much less still. If a person is going to have a a radiant floor heating system, then they absolutely should insulate the slab edge. There are products available that have a hard styrene material surrounding the insulation. The hard coating (1) looks good, and (2) has a key that ties into the slab so that termites cannot pass between the two building elements. The insulation is used as the form when pouring the slab.

Nehemiah Stone


On Tuesday, March 4, 2003, at 05:22 PM, John Swearingen wrote:

I agree with John Straube about not using slab insulation in SUNNY
California. We have areas that have severe winters and deep frosts, but in
most areas we are designing for cooling loads more than heating.
Experience, as well as computer simulations, show about a 5F lowering of ambient temperatures for four or five summer months when slab insulation is removed. The corresponding increase in heating loads is usually minimal and
only significant for a couple of months.

John

-----Original Message-----
From: GSBN [mailto:GSBN@...]On Behalf Of John Straube
Sent: Tuesday, March 04, 2003 1:35 PM
To: 'GSBN'
Cc: bainbrid@...
Subject: RE: GSBN:Re: : slab edge insulation


I would not use any insul below slabs in sunny california, but would use
it on the stem wall.
Protection is easy -- you plaster bales? Well you can plaster the foam
too. The termites are a bigger issue, best solved IMHO with a peel and
stick over the concrete and down the face of the foam/Mineral fiber 2",
then plaster over.


-----Original Message-----
From: GSBN [mailto:GSBN@...] On Behalf Of Bob Bolles
Sent: March 4, 2003 12:11
To: GSBN
Cc: bainbrid@...
Subject: RE: GSBN:Re: : slab edge insulation


Hi John
You wrote"
<snip>
"Finally, if you are using a concrete foundation, adding a couple
inches
of foam or fiber insulation to the exteiror of the foundation is likely
to be easier and high performance"

Well, therein lies the problem
If you place the foam on the exterior, first there is the appearance
issue, as well as protecting it from damage. Then, I have to ask if this
would potentially provide a path, behind the foam or through it, for
termites, ants and other little critters?

I believe that insulation under the slab is probably appropriate for
cold climates, but I am working in sunny Southern California. How much
insulation should we use, if any, below the slab.

Regards
Bob

Bob Bolles
Sustainable Building Solutions
Bob@...
www.StrawBaleHouse.com
 "They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety"  Benjamin Franklin


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