This post is part of a series of notes and guidance about Buildings.
Airbricks will normally be inserted into a wall, in the place of a normal brick, to provide a passageway for air to ventilate an unheated void. The void could be cavity in a wall, a small storage space or most commonly the space underneath a suspended ground floor.
An open gap would also serve to provide ventilation, but airbricks have the added benefit of having a series of 'perforations' or holes that are small enough to stop small animals (typically mice or rats) entering.
- What do they look like?
Airbricks are most commonly clay/terracotta, metal or plastic. Below we show a clay airbrick and a metal one. The second picture showing metal one is the more common size.
- Why are they important?
Without ventilation unheated spaces will tend to suffer from condensation or dampness, so the gentle flow of air through the airbricks will allow that moisture to dry and escape. If these areas do stay damp or moist then there is a very high risk of decay, wet rot, dry rot and mould forming. This could have serious consequences for structural wood and timbers.
- What can go wrong?
Airbricks are pretty simple things really, no mechanical, electrical or moving parts, so the airbrick itself is unlikely to go 'wrong' in terms of the function it provides. With age, deterioration could occur (with rusting, corrosion or crumbling of the materials) but this is not going to be adversely affecting the passage of air.
However, the most common problems that we do see include:
airbricks being covered-over by paths/drives/flower beds being built-up too high;
building-over the original airbricks when an extension is added and removing the cross-flow of air from one side of the building to the other;
there not being a sufficient number of airbricks around the perimeter of the void;
airbricks being too close to the ground and rainwater running through. This is a concern in flood risk areas, where special airbricks can be used with built-in flood protection (these do have mechanical parts).
These all happen when builders/homeowners do not understand the purpose of airbricks and the consequences that can arise through a lack of ventilation.