Vapor Barrier For Existing Concrete Slab

For good thermal transfer from the concrete to the wood flooring there should be no insulating layer between them. A radiant slab must have both a vapor barrier and foam insulation underneath otherwise you risk a constantly damp floor and will be heating the ground more than the house. This guide says in section 2 4 1.

Aci 302 1r 11 guide for concrete floor and slab construction doesn t advocate universal use of vapor barriers but does make recommendations for their proper use. It is also possible that too much water or cement paste would be absorbed from the concrete by the sand but probably not under most circumstances. Puncture studies of 6 8 10 and 20 mil vapor retarder materials have shown that 10 mils is the minimum thickness that should be considered and thicker material may be necessary over.

The american concrete institute s guide for concrete floor and slab construction recommends that the thickness of the vapor retarder be at least 10 mils. A vapor barrier should be used for all concrete floors and slabs that are going to receive an impermeable floor finish like epoxy laminate linoleum and wood or if the concrete floor will be used for any purpose where the passage of water vapor through the floor may create problems. However the choice between vapor barrier or vapor retarder can become a gamble of upfront costs vs.

Accordingly standard practice for concrete slabs in most situations is to install a vapor barrier or vapor retarder to inhibit the amount of moisture that can contact the underside of the slab. Vapor and gas barriers. The use of underslab vapor barriers is the best method and most economical solution for controlling water vapor migration through concrete slabs.

Uncontrolled water vapor through concrete slabs has cost building owners designers and contractors billions of dollars. The existing mat slab does not have a vapor barrier and i m proposing a vapor barrier above the mat slab along with sleepers and rigid. Vapor barriers are used because while fresh concrete is poured wet it s not supposed to stay that way.

A concrete vapor barrier is any material that prevents moisture from entering a concrete slab. The garage was built in 1922 slab on grade and no underslab vapor barrier is assumed. I am an architect in los angeles designing a conversion of existing garage to an accessory dwelling unit adu.