Dictionary of Moisture Protection & Restoration

Barrier Systems (continued) The barriers are as much systems as they are materials. The function of the barriers is to prevent any water penetration into the substrates. They include metal, glass, and composite materials such as sheet and liquid membranes for vertical and horizontal applications. The most popular system today is the elastomeric, which is a waterproofing material with the ability to return to its original shape and size after substrate movement during expansion or contraction. Elastomeric is used mainly as a remedial system, because the original barrier, such as the building paper, is no longer performing, or the original design or application was not adequate. Elastomeric works the same way as your skin; it allows the flesh (substrate) to breathe, but does not allow the water to penetrate. In most cases, the original barrier is abandoned when the elastomeric coating is applied. It is an economically attractive option compared with the cost of removing the sacrificial materials and the building paper then reinstalling the barrier. Elastomeric materials should not be considered as a technological breakthrough, but as an economical way to provide an alternate barrier. As the original barrier and diversion system are abandoned, the barrier is moved to the surface of the wall where transition joints are critical.

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