Preventing Moisture Penetration Maine

Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: September 1, 2003

I have seen many warehouses built with single wythe concrete masonry walls. How does this wall prevent water from penetrating into the interior?

Water penetrates the untreated exterior face of concrete masonry walls just as it does the exterior face of clay masonry walls. This fact is the reason why cavity walls are popular in masonry installations.

In a cavity wall, water that penetrates the exterior wythe is prevented from reaching the interior wythe because of the open air space between the two. When single wythe masonry walls are used, a coating must be applied on the face to stop water from penetrating in the first place, or the walls must be designed so that the cells of the concrete masonry units function as a drainage cavity.

Probably the most common approach with single wythe concrete masonry walls is to use a sealer or elastomeric coating on the exterior face to prevent water penetration. This coating generally needs to be capable of bridging small cracks that may form in the exterior face of the wall system.

In some cases, a water repellent may be effective, but there must not be any significant voids, separations, or cracks in the wall system. Also, the surface of the concrete masonry units must have a relatively fine texture.

The wall system must contain control joints that are spaced closely enough to prevent shrinkage cracks from occurring.

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