A sealed, empty gap left between two layers of building materials, such as exterior masonry and interior framing. Because the trapped air cannot circulate to transfer heat via convection, it acts as a natural thermal barrier. It also helps prevent moisture from bridging the gap between the outer and inner walls.
Heard on the job
We need a full one-inch dead-air space behind the brick veneer to meet the insulation specs.
Insider tip
If mortar droppings fall into the cavity and bridge the gap, the dead-air space loses its insulating value and creates a path for water intrusion.
Also heard as
- Dead airspace
- Air cavity