A cavity is an enclosed space created by the design and positioning of a building’s structural elements. Common examples include gaps between walls, floors and ceiling voids. However, they do not include ducts, conduits, chutes, pipes, and other cavities that serve a distinct purpose. These cavities are often hidden, but they must be adequately sealed as part of a structural fire protection strategy.\
In the event of a fire, gaps between walls and floors can create ‘air buoyancy’, a push-and-pull effect caused by differences in air temperature. That can enable flames and smoke to quickly move between different areas of a building, otherwise known as the ‘chimney effect.’ Simply, these gaps allow heat, flames, gas, and smoke to travel unhindered from one building area to another.\
The upward flow of air, heat and flames creates significant challenges for fire safety in tall buildings. A fire that starts on the ground floor and moves up through empty cavities can accumulate on higher levels, with no place for hot air and smoke to escape. Therefore, cavities in a building must be appropriately sealed.