Cavity walls feature a hollow space between the outer and inner wythes, connected only by corrosion-resistant metal ties. When water seeps through the outer wythe, it descends within this cavity, intercepted by flashing and eventually exiting through weep holes. To enhance moisture resistance, the inner wythe's cavity side often receives damp-proofing, doubling as an air barrier. The cavity can also house insulation to mitigate heat transfer.
Maintaining a clean cavity during construction is crucial to prevent blockages that could hinder drainage. Traditional practices involve placing steel ties within the cavity to catch the droppings, which are then pulled out. However, innovations like beveled bed joints and mortar deflection materials are more effective and easier to use in preventing mortar from entering the cavity. In terms of structural roles, the inner wythe bears load in load-bearing walls, while in non-load-bearing variants, it supports only its own weight, relying on metal ties for lateral stability. Various constructions use this design, including brick veneers with different backings, highlighting the versatility and importance of cavity walls in modern masonry.
