What is the typical cavity wall air space?

• A. 1 inch
• B. 3 inches
• C. 2 inches
• D. 4 inches

Answer: (C)

In a cavity wall, keeping a gap between the outer brick veneer and the inner structural wall is essential to manage moisture and airflow. The typical width of that air space is about two inches. This space allows any moisture that penetrates the veneer to drain down and exit through flashing and weep holes, rather than wicking into the inner wall. It also gives room for components like ties and flashing to fit without blocking drainage, while still letting the wall dry out.

One inch is usually too narrow for proper drainage and flashing clearance, which can lead to moisture issues. Four inches would add unnecessary thickness and cost for most standard constructions, offering no substantial benefit in ordinary conditions. Three inches is also not the common practice, though it might occur in specialized designs.

So, two inches is the practical, widely used cavity width that balances drainage, drying potential, and construction ease.