Sub-slab insulation
I was planning on using 4″ of Type II EPS covered with 10 mil Stego under my slab and 2.5″ of EPS on the basement walls. I spoke with my concrete guy today and he told me they have been using this product:
http://www.insulationsolutions.com/products/insultarp/information.html
Anybody have any experience with this product? They claim an r-value of 5.9. That would be half the r-value of the 4″ of EPS, but how does that actually compare in terms of heat loss where the sub slab temps are worst case high 40’s in the winter time. It would save me a lot of time if I could use this and I would still plan on insulating the basement walls where more of the heat loss is going to occur. Note that the link show the tarp being used in a radiant flooring application which I will not have.
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These bubblewrap products seem like hype to me. I say to go with the tried and true methods under slab. You will never have another chance to improve it later. My 70 year old father and I just put 4" foam last week for my 900 ft^2 slab (poured today) and installing the two layers of 2" thick sheets took less than 2 hours. If you can source reclaimed foam, the payback will be very good.
Here's a thread about it from elsewhere: https://forum.heatinghelp.com/discussion/109737/has-anyone-use-insultarp/p2
I must say that I'm very suspicious: at 1/2" (slightly compressed) the R 5.9 is absurd. The reflective aluminum layers will do nothing as there are in direct contact with the material above and below.
Jonathan,
Whoever told you that Insul-Tarp, when installed under a concrete slab, has an R-value of R-5.9, is engaged in a scam. Even though the manufacturer of Insul-Tarp has already been cited by the FTC for violations of the R-Value Rule, distributors of Insul-Tarp continue to lie. For more information on this type of product, and on the FTC's attempts to crack down on Insul-Tarp, see this article: Stay Away from Foil-Faced Bubble Wrap.
There is no R-value associated with a radiant barrier installed under a concrete slab. Stick with the 4 inches of EPS.
Insul-Tarp has a layer of closed cell polyurethane in it, but the overall thermal performance claims are pretty much BS.
The R5.9 is met only when tested in it's full 3/4" loft uncompressed state. In-situ compressed to half inch, the entire 8" stackup (that includes the 4" slab and the gravel & sand layers below) tests at R6.8, per their marketing sheet:
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Insul-Tarp R-Value
Material R-Value of Insul-Tarp (¾" material only) at a 75° mean temperature regulated by
Federal Guidelines 16 CFR 460.5:
Mean Temperature .......................75°F
Average Thermal Resistance (R) ...5.9 hr-ft²-°F/Btu as per ASTM C 518-04
The System R-Value was tested in a concrete slab configuration consisting of a 4" concrete
slab, ¾" Insul-Tarp insulation (½" compressed), 2" gravel and 1" sand. The total slab con-
figuration was approximately 8". The System R-Value at a 75° mean temperature:
Mean Temperature .......................75°F
Average Thermal Resistance (R) ...6.8 hr-ft²-°F/Btu as per ASTM C 518-02
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http://www.mqb.com/customer/mcbain/pdf/informationalFlyers/Insul-Tarp-lr.pdf
Just a WAG: In the compressed state it's adding MAYBE R2.5 - R3 to the total stackup, and that is only assuming it will sustain that 1/2" loft over time.
An inch of sub-slab foam would outperform it.
BTW: Why only R10 on the walls, but R16 under the slab? Is the plan to add a non-structural insulated 2x4 studwall on the interior side of the wall EPS? (An insulated studwall would bring it up up to something like ~R20 whole-wall, after accounting for the thermal bridging of the framing.)