Slab Pour Over with Pex Advice needed?

Paul Pollets

An R10 thermal break with perimeter insulation should be used to separate the overpour from the existing slab. R10 is equivalent to 2" foamboard. Another method would be to use 3/4" plywood over the existing slab and use 1/2" panels made by Wirsbo (QuickTrak) or the Viega "Climate Panel", which will reduce head height over the gypsum overpour. If the floor isn't level, its difficult to put down the ply. Foil will be a poor thermal break, but it's better than none at all. We're required to do the R10 over existing slabs in Seattle. Check your local building codes.

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Heatmeister_2

Need Input for a Gypcrete Pour Over Existing Slab with Pex.

Can I get the recommended approach for what goes on top of an existing concrete basement foor that is uneven at best, 50-60year old. I hear Maxxon Thermafloor gypcrete is the ideal solution for pouring over pex. However, what is the CORRECT approach without decreasing my ceiling height too much. I have heard of "the barrier" material, pink foam etc... Is there a product like a thin 1/2" foil backed insulation material that I can use instead of 2" pink foam before the pour over?

Also, is 3/8" pex 6" on center better than say 5/8" or 1/2" at 12" on center in a pour over application to avoid cold spots?

Thanks

Unknown

Why do you want foil backed, for a vapor barrier?

EPS comes in 1/2". it's only an R 2 or 3 but that's more than you'll get with a foil product. Depending on your downward losses and floor coverings it may be fine.

Don't go over 9" o.c. if you can help it. 3/8" is fine if you want to use it but you will need shorter loop lengths.

Heatmeister_2

Thermal Break

Sorry for my question but are you suggesting that an R10 Thermal Break is in fact the 2" pink foam? I am trying to avoid this b/c it will decrease my overall height by 3 1/2" once all is said and done......not to metion mess up my risers on my stairs? You did bring up an interesting question though, and that is whether or not I must compy by a code before I do this.

hr

You will have to compromise somthing

Ideally a 2" foam would be nice. It may not work with your floor elevations, etc. Anything is better than nothing, even a 1/2" foam.

Just be sure the gyp manufacture okays this. Gyp is not a structural product like concrete. I'm not convinced it could be poured over a soft foam without cracking and structural issues.

That a lot of $$ to gamble with. Get an answer, in writing, from the manufacture.

hot rod

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Heatmeister_2

Thanks again hot rod

I am looking into "the barrier" it may be just right for my application.

Here is the product I am looking at for gypcrete. http://www.maxxon.com/product_detail.asp?ID=4

I will check into, but the mfg. is the one who suggested foam. He says they have 2500psi?

Unknown

you're better off with a 1/2" of XPS.

hr

Barrier is

pretty soft stuff. I leave shoe prints in it when I walk across it!

I think, also, you want to glue down whatever product you insulate with. I don't think the weight of a thin gyp pour would hold down those foam products and the surely will FLOAT, during the pour. Lots of water in gyp.

I'm not feeling real good about your plan. Ask some of the licensed gyp installers how they handle this application.

I'd feel much better if you got advise from someone that has actually walked this road. The gyp manufactures should list licensed installers in your area.

Shout out for Troy Morgan in western New York www.radiantfloorheat.com He has done some really clever things with gyp and is a licensed, EXPERIENCED Infloor certified installer.

USG has some really high psi gyp they claim you can color, stamp, and use as a final wear surface. Keep looking for the correct answer

hot rod

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