Cavity Drainage Mat

What does Cavity Drainage Mat Mean?

Definition of Cavity Drainage Mat in Construction
What is a Cavity Drainage Mat? Within a masonry wall system is normally an air cavity. This cavity is designed to drain the water that penetrates the exterior masonry wall system down to the bottom of the wall assembly, or down to the structure supporting the masonry wall. It is critically important that this cavity be kept clean of mortar or materials created during the installation of the masonry system. The normal construction of a brick wall requires that a mortar bed be troweled on the top and each successive masonry course, resulting in mortar falling down the interior of the cavity. Again, it is important that this cavity be kept as clean as possible. The cavity drainage mat is a layer of woven fiberglass, or other synthetic material, that is placed at the bottom of the masonry wall within the cavity. This mat normally extends up the wall a couple feet and is dependent upon the actual masonry design. The function of this cavity drainage mat is to allow some of the mortar or grout to accumulate at the top surface of the mat, however still allowing the drainage capability of the water running down the interior of the cavity . The weep holes, that are specifically designed and placed to channel the water out of the cavity, to the exterior, are positioned within the bottom of the cavity drainage mat. The entire operation and installation of the mat, is to ensure that the water has the capability of draining out, to the exterior facade.