An air brick is a vent that allows air to pass through a wall to the underfloor space. It is typically made of terracotta or plastic and is installed in the external walls of a building to provide ventilation to the subfloor area.

In commercial construction in Australia, air bricks are commonly used to prevent dampness and moisture buildup in the subfloor area, which can lead to structural damage and mold growth. They are also used to allow for the circulation of air, which helps to regulate the temperature and humidity levels in the building.

Air bricks are typically installed at the base of the external walls, below the damp proof course (DPC), and are often covered with a grill or mesh to prevent debris and insects from entering the subfloor space. The size and number of air bricks required will depend on the size and design of the building, as well as the local climate and environmental conditions.

It is important to ensure that air bricks are installed correctly and maintained regularly to ensure proper ventilation and prevent moisture buildup in the subfloor area. This may involve cleaning the air bricks to remove debris and ensuring that they are not blocked or damaged.