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Home/DIY projects/Walls/Fitting an airbrick

Fitting an airbrick

Summary: Learn how to fit an airbrick.

Airbricks are positioned in walls to ventilate a room or under-floor area. Airbricks can be made of clay, galvanised steel or plastic and are one, two or three bricks deep. All airbricks must conform to BS493. To provide under-floor ventilation the airbrick should be located at least 150mm (6in) above ground level but below the damp-proof course. Airbricks can also be sited just below the ceiling to provide ventilation to a room. A damaged airbrick can offer a way into the house for vermin and should be replaced as soon as possible. Never block an airbrick even as a temporary measure as this can lead to rotting joists and floorboards.

Preparation

  • When fitting an airbrick to provide under-floor ventilation you can only work from outside. 
  • To make the hole remove a house brick by chipping away at the mortar with a club hammer and cold chisel. Drilling a series of holes into the mortar around the brick using a masonry bit can speed up this task. The holes should be about 100mm (4in) deep.
  • Remove the brick and clear away as much mortar from the cavity as possible.
  • With a cavity wall, you need to remove the brick from the inner wall. For this task you can use the same method employed in removing the brick from the outer wall, but you will need a longer masonry bit to drill the holes and a longer cold chisel.
  

Fitting the airbrick

  • In a cavity wall, to prevent the air being lost in the cavity, a plastic airbrick fitted with a telescopic sleeve should be used to bridge the gap.
  • Once the telescopic sleeve is in place, mix up a small amount of mortar using one part masonry cement, five parts building sand and water.
  • Moisten the edges of the hole with water and then with a bricklayers trowel spread the mortar along the bottom edge of the hole.
  • Apply mortar to the top and sides of the airbrick and push it into place.
  • Tap the airbrick with the handle of the trowel so the airbrick is flush with the surrounding brickwork.
  • Remove excess mortar from around the airbrick and point the joints to match the rest of the wall.
  • With a stick or length of wire poke through the holes to ensure there is no mortar blocking them.
  • To provide extra ventilation to a room, an airbrick can be fitted higher up the wall. If inserting an airbrick above the damp-proof course, the telescopic sleeve must have a cavity tray fitted to shed the moisture that penetrates the cavity above the unit.
  • A ventilation grill should then be screwed over the hole in the wall inside the building.

A plastic airbrick fitted with a telescopic sleeve should be used to bridge the gap in cavity walls.

If inserting an airbrick above the damp-proof course, the telescopic sleeve must have a cavity tray fitted to shed moisture.


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Tools Needed
  • Power drill and masonry bit
  • Club hammer
  • Cold chisel
  • Bricklayer's trowel
  • Screwdriver
 
Materials Needed
  • Airbricks conforming to BS493
  • Plastic telescopic sleeve
  • Mortar - masonry cement and building sand
  • Ventilation grill
  • Wall plugs
  • Screws
 
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