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How do cavity walls improve insulation and resist moisture in cold climates?

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construction of apartment buildings — construction Apartment buildings under construction in Cambridge, England.

A cavity wall is a double wall construction consisting of two vertical layers of masonry, known as wythes, separated by an air space and connected by metal ties.1

Thermal Insulation

The air space between the two layers acts as an effective thermal barrier. Because air is a poor conductor of heat, this design significantly reduces heat loss; cavity walls have a heat-flow rate that is approximately 50 percent that of a solid wall, making them highly efficient for maintaining warmth in cold climates.12

Moisture Resistance

In addition to thermal benefits, the cavity serves a critical protective function against water infiltration. If moisture penetrates the exterior wythe, the air space allows that water to drain away safely rather than passing through to the interior of the building. This dual-purpose design makes cavity walls a reliable choice for both bearing-wall construction and non-load-bearing infill for framed buildings.1