Put Plastic Under Concrete Slab

It doesn t really matter very much whether the pex is near the bottom of the slab in the middle of the slab or at the top of the slab as long as there is plenty of insulation under the slab.

Put plastic under concrete slab.

Vapour barriers are the black plastic that builders put under residential house slabs. Why a plastic vapor barrier under concrete slab mondays withinstall the proper type of vapor barrier siouxland homesare vapor ers necessary for bats and garagesvapour barrier under concrete. Plastic under concrete floor or not. There are debates about this with varying national regional state and local regulations.

One laboratory drying study indicated that 4 in. A concrete vapor barrier is simply a sheet of polyethylene plastic visqueen placed directly on top of the sub grade before the concrete floor or slab is poured to help keep moisture from the soil from passing up through the concrete. The other contractor says no way no plastic holds the water in the concrete during the drying process and can leave webbing like visual affect in finish of concrete. They do this for two main reasons.

The american concrete institute states that a vapor retarder should be placed directly under a concrete slab on grade if now or in the future a low permeable membrane floor finish will be installed upon the slab. So yes a vapour barrier is required under a concrete slab for a class 1 building a dwelling and for class 10 eg a garage where the slab is continuous with the dwelling. One contractor says to put plastic under the concrete it prevents moisture from coming up into the concrete. Thick concrete samples having a w c 0 50 and sealed from below required 82 days for the vapor emission rate to reach 3 0.

Thanks for the question. This was verfied by some field studies conducted by concrete construction magazine. Aci 302 1 guide for concrete floor and slab construction states that the minimum thickness of an effective vapor barrier is 10 mils. Don t worry if the concrete contractors put a few holes in the poly.