London Builders - Air Bricks

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Most properties with wooden floors on the ground floor will have a void underneath. Air in this void can get stale and humid. Humid air carries a great deal of moisture which, at night when the heating is off indoors, can condense on the cooler surface of the floor joists or boards. This condensation can cause the boards and joists to rot from the underside.As with all condensation related problems the only treatment is ventilation and all properties with hollow floors have air bricks built into the wall to allow a free flowing passage of air. The down side of these air bricks is that the air under the floor can produce a bit of a draught up through the gaps in the floor boards. Many properties, because the owners new no better, have had the air bricks blocked up or even removed. Some have had some blocked up on oe side of the house and the other sie has been left open and lastly, because these days a conservatory is a relatively cheap and easy way of getting an extension, the floor slab of the conservatory has blocked up the air bricks.It is important that these air bricks are opened up again. They must be all round the house to allow the air to flow back and forth. Recommended spacing is 1800mm.

If your floor is draughty see our project on filling gaps in floorboards, but do not block the air bricks. At best you will get some damp and mould and the worst case scenario leads to dry rot.

Air bricks can be inserted easily enough. The first stage is to remove a section of wall large enough to insert one. No lintel is necessary over an air brick. In most situations for hollow floors a 9 inch x 3 inch air brick will be adequate providing there are enough of them at a suitable spacing. Air bricks can be bought in clay or plastic.

See video clips with our works here