Many traditional properties are built with a suspended wooden floor which sits above a void air space between the perimeter walls and ground. If this space is not ventilated, the air in it becomes stagnant and humid, and the moisture within it begins to condense on the brickwork and flooring. Over a prolonged period, this moisture causes the floor to rot from the underside.    

To avoid this situation airbricks must be positioned  in the wall such that air can exchange freely between the sub-floor void and the outside. The airbrick should be inserted into the exterior leaf of the wall and cut through the interior leaf of the wall as well, incorporating a through wall cavity sleeve and thereby maintain the through flow of air to the sub-floor void.