Moisture Barrier Under Concrete Floor. Once the slab is poured, the excess moisture must leave the slab in order to strengthen the concrete bond. However, allowing excess moisture to leave the slab after it's poured is crucial to a successful flooring installation. Since concrete is porous, water vapors transmits from the ground through the concrete slab into your basement.
Concrete is porous by nature and, even though the moisture near the surface of the concrete evaporates as it cures, moisture from below the concrete or within the concrete will tend to osmotically migrate up through the concrete capillaries, to escape through the path of least resistance. In the old days, not much — just dirt. Water is an inherent part of the hydration process of concrete.
Gallery of Moisture Barrier Under Concrete Floor
15 mil vapor barrier by americover: Special plastic sheets are laid on the ground before concrete is poured, completely isolating the slab from the ground. The minimum moisture or vapor barrier for use under concrete is a class 1 vapor retarder, with a rating of 0.1 perm imp or less. A sand layer should not be installed between the vb and the concrete.
