Concrete Slab Vapor Barrier Repair

Architects engineers and contractors therefore often disagree on whether concrete should be placed directly on the vapor barrier or on a granular base placed over the vapor barrier.

Concrete slab vapor barrier repair.

It successfully alleviates the problems associated with moisture accumulation in a concrete slab keeping moisture from reaching the epoxy flooring system. But consider going with a barrier that has water vapor permeance less than 0 3 perms. Choosing a vapor barrier. However the current practice recommended by the american concrete institute is to apply a heavy grade non penetrable vapor barrier or retarder with the lowest possible permeance for the application over a layer of granular fill crushed rock gravel etc.

Do not pound form stakes through the vapor barrier. To minimize cracking on top of vapor barriers use a 100 mm thick 4 in layer of slightly damp compactible drainable fill choked off with fine grade material. All vapor barriers should conform to astm e 1745. If concrete must be placed directly on polyethylene sheet or other vapor barriers placed directly on polyethylene sheet or other vapor barriers use a mix with a low water content.

Cure with waterproof sheets rather than with water or curing compounds. Seal all vapor barrier seams with the tape provided by the barrier manufacturer. Vapor barriers have been associated with certain concrete slab on grade problems including curling and cracking. But they have also proven to be beneficial in reducing failures of moisture sensitive flooring materials adhesives and coatings caused by excessive emission of moisture vapor from concrete slabs.

The concrete slab is then poured on top of it. For most residential applications the 10 mil under slab vapor barrier will offer enough protection against moisture vapor transmission coming up through the concrete floor allowing for flooring materials to be successfully installed on top of the concrete. Seams should overlap 6 inches. Water vapor diffusing through the concrete slab can also lead to deformation and discoloration of the floor covering material leading to costly repairs or even replacement.

Some supports come with wide bearing pads. Water below the concrete slab can diffuse through the slab as vapor then condense under the flooring which can emulsify some adhesive and destroy the floor covering. Studies have shown that vapor barriers can affect the behavior of the concrete slab and significantly influence finishing time cracking and strength. Another solution is the new vaporstake that seals to the vapor barrier and is then cut off and left in the slab.

For most commercial applications the 15 mil thick concrete vapor barrier will be a better choice.