Concrete Slab Vapor Barrier Installation

If the subbase is sharp angular gravel a thin layer of sand can be placed on top of the gravel subbase next to the vapor barrier.

Concrete slab vapor barrier installation.

Minimize water vapor moving through a slab by choosing the right vapor barrier and installing it properlyby bill palmer concrete network columnist. In general place the concrete slab directly on top of the vapor barrier with the subbase below. A concrete vapor barrier is any material that prevents moisture from entering a concrete slab. The sand should be compacted before concrete is placed.

The last thing you want your customers to envision when thinking of a concrete floor is a damp cold basement slab. Because extruded polystyrene insulating board will absorb little moisture the vapor barrier can be placed above or below the slab insulation. Using a utility knife cut the length long enough to wrap edges up the wall 3 4 inches. Given the many applications a vapor barrier is one of the most critical building components used to prevent indoor air quality issues and minimize moisture related concrete slab and flooring system failures.

A pro s guide for below slab vapor barrier installation by dan marks 01 14 19 this helpful guide to under slab vapor barrier installation will consider the most common slab designs their terminating edges and how to seal at to the perimeter of your foundation in accordance with your designer s specifications and astm e1643. See below for more discussion on this. 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 angular base materials. Tips for concrete floor vapor barrier installation.

If ground conditions require their use a 3 inch 75 millimeter layer of sand over the vapor barrier and under the concrete has been shown to reduce these problems. Vapor barriers are used because while fresh concrete is poured wet it s not supposed to stay that way. Updated july 10 2020. 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.

One of the reasons those old basement floors were like that was because they had no vapor barrier beneath them leaving an easy path for water vapor from the soil to migrate into the slab assuring that the. May be higher check job. For a vapor barrier below a concrete floor slab most choose 6 to 10 mil polyethylene. Additionally installation of a vapor barrier may help to contribute to leed.