Photo Credit: Alex Mead
Seen here is a cavity wall under construction. A cavity wall is a type of masonry wall that is a composite of both concrete masonry units (CMU) and bricks or stones. It works by creating a gap between the building and the façade we see on the street made of bricks or stones. The black portion of the building is a waterproof coating on the CMUs that inhibits moisture from entering the building. The green (to the left of the black, next to the stones) is screen like material that keeps mortar from falling down the cavity and blocking the drainage ports at the bottom. The stones or bricks then go on the outside of this screen material to finish the outside of the building. The stones or bricks are connected to the CMUs by wires that extend and keep the stones aligned vertically, but carry no gravity load. One advantage of wall construction of this type is the stones or bricks can then move freely with temperature variations and won’t crack or affect the inner CMU wall. This design also allows for a not perfect water seal to be used on the stones or brick because the waterproofing is the black coating behind the visible finish
Learn more about Cavity Walls