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.
A masonry cavity wall consists of two wythes separated by a hollow space. The outer and inner wythes are connected using corrosion-resistant masonry ties for structural stability.
When water penetrates the outer wythe, it enters the cavity and is collected by a thin impervious membrane called flashing, which is installed at the cavity's bottom and drained out through weep holes.
Additionally, dampproofing material applied on the cavity side of the inner wythe will protect the interiors from water penetration and also serve as an air barrier.
During construction, debris like mortar droppings can block the drainage system, making it crucial to keep the cavity clear. Using mortar deflection material can help avoid blockage of drainage in the cavity.
The cavity facilitates sound insulation and the placement of conduits for utility distribution within a building.
Also, inserting insulating boards of rigid foam plastic in the cavity can provide thermal insulation.
Cavity walls can be load-bearing or non-load-bearing. In load-bearing cavity walls, the inner wythe supports structural loads, while the nonstructural outer wythe is a veneer.
In non-load-bearing walls, the inner wythe provides lateral support to the outer wythe through the masonry ties.
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