![]() ![]() However, single-wythe walls do not have a drainage cavity other than the inside voids in the CMU or brick. Flashings are provided at the same locations as in veneer construction. Sometimes, water repellents and masonry sealers are used. Water must be resisted at the outside face of these walls. As such, they can also function as load-bearing walls. The cores of single-wythe CMU walls can be filled with reinforcing steel and grout. These walls do not include a drainage cavity. Single-wythe masonry walls (one vertical row of masonry one unit in thickness) are predominantly constructed with CMU but can be constructed with brick. Since water that penetrates the masonry veneer can flow unobstructed down inside the wall, the proper installation of the flashings is more critical than in a thicker masonry wall system. For this type of wall to function properly, the drainage cavities have to be kept clear of mortar droppings and other blockage. The water is then expelled from the cavity back out of the building by the flashings. This cavity allows water to flow down the backside of the veneer. These walls accommodate inevitable water penetration through the masonry veneer with a drainage cavity. Masonry veneer construction consisting of a single-wythe of brick/masonry over a back-up wall system, which gained popularity in the 1950s, is a departure from thicker load-bearing wall construction. Sometimes, masonry ledges or projecting elements (often referred to as water tables) deflected water off the fa?ade as it flowed down the face of the building. These flashing materials were typically made of soft metals such as copper or lead. Often, the flashings extended completely through the wall. Flashings in these walls typically occurred at junctures of roofs and walls and at parapet locations. Load-bearing walls performed well as long as it stopped raining before water was absorbed all the way through the mass of the wall. Water infiltration in load-bearing walls was resisted by the mass of the multiple-wythe wall and a few well-placed flashings. Older masonry buildings were constructed with thicker, solid, load-bearing walls. In order to understand how masonry wall flashings work, it is important to first understand the different types of masonry walls. Flashings are also used under masonry copings, sills, and other horizontal surfaces. Wall flashings are typically required at locations where the downward flow of water inside the wall would be obstructed or interrupted. The purpose of this article is to discuss the design and installation of masonry wall flashings at several typical locations throughout a building. Water can enter the wall system at numerous locations, including individual masonry units, mortar joints, the interface between the mortar and the masonry units, at the tops of walls, at cracks, and at penetration details such as windows, doors, and pipes. ![]() This penetration has to be managed by flashings, which divert the water back to the exterior. The masonry industry understands that water penetration through the outer wythe of veneers will occur. Masonry walls, which are largely composed of brick, concrete masonry units (CMU), cast stone, and other related units, typically absorb moisture and rain. Preventing water leakage through masonry fa?ades in contemporary construction is primarily accomplished by the use of well-placed flashings. ![]()
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