Concrete Slab Vapor Barrier Repair

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.

Concrete slab vapor barrier repair.

Vapor barriers have been associated with certain concrete slab on grade problems including curling and cracking. Choosing a vapor barrier. Seams should overlap 6 inches. It successfully alleviates the problems associated with moisture accumulation in a concrete slab keeping moisture from reaching the epoxy flooring system.

For most commercial applications the 15 mil thick concrete vapor barrier will be a better choice. Cure with waterproof sheets rather than with water or curing compounds. The concrete slab is then poured on top of it. 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.

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. Another solution is the new vaporstake that seals to the vapor barrier and is then cut off and left in the slab. Some supports come with wide bearing pads. Seal all vapor barrier seams with the tape provided by the barrier manufacturer.

Studies have shown that vapor barriers can affect the behavior of the concrete slab and significantly influence finishing time cracking and strength. Do not pound form stakes through the vapor barrier. 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. The moisture vapor barrier helps reduce the passage of fluids through concrete.

But consider going with a barrier that has water vapor permeance less than 0 3 perms. 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. If you want to make sure your slab on ground gets dry and stays dry use a vapor barrier. 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.

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.