Friday, 24 August 2012

The Air Brick Liner Swift Brick

In ancient times, Swifts nested wholly in natural places, such as holes in trees, sometimes made by woodpeckers, or in rock faces. Then a new source of nest sites appeared when we unintentionally provided spaces in our buildings, and doubtless the swift population greatly increased. Now that we are destroying nest places with roof renovations and roof insulation, the time has come to deliberately incorporate nest places in new buildings. We previously reported on the rescue of a Swift colony in St Neots, using air brick liners for swift bricks. The success of this has lead us to refine our ideas and report fully on how such air bricks may be deployed more widely.

Contributed by Bill Murrells & Dick Newell


Swift brick. [since this picture was taken, we now
use 'undercloak' for the ends, a low cost, strong, asbestos
substitute].

The picture at left shows A swift brick made from a standard, clay air brick liner of length 200mm. The internal floor area is 200mm x 175mm, diagonal 266mm), and the internal height is 100mm. This is big enough for any swift to turn around, without bending its wings and it is large enough for a young swift to exercise. The outside dimensions of this brick are 200mm (plus 2 slates) x 215mm x 140mm.

At least 2 of these were occupied at St Neots in 2012, so they are accepted by swifts.

The air brick is the model 401 (see PDF on page 9). The ends, made of slate, or under cloak, are glued on with resinous glue. The air brick is available in any length up to 300mm. Although swifts will use an air brick 200mm long, They may prefer something longer, so that they can get further from the entrance.  From a swift's point of view, a brick 300mm long would be luxurious, 225mm (the length of a standard brick) could be a good length to go for. The computer models below illustrate air bricks in 2 situations. This brick occupies the space of 1 house brick horizontally and 2 courses of bricks vertically. Its internal floor area is 200mm x 175mm (diagonal 285mm),  height 100mm; the outside dimensions are 200mm (plus 2 slates) x 215mm x 140mm

Four SB-225's in a gable end
Two SB-225's under a soffit - from below
The ideal location for installing air bricks is as high as possible under the eaves or in a gable end. It is possible to hide much of the brick behind a barge board or within the eaves. They would also go well in the middle of a wall, but in such places where they could get wet, then a cavity tray might be needed (a piece of felt below and behind the swift brick)

Two SB-225's under a soffit - from above

The advantages of this swift brick are that it is made of approved building materials, it looks aesthetically pleasing, it is easy to make and easy to install, it is a good size for swifts and it is made of low cost, readily available materials; the basic air brick costs less than £10. It merely requires an angle grinder to fashion the entrance (a slot 65mm x 28mm), and some glue.

Thus we think that it should be acceptable to architects and builders, as well as being desirable for swifts.

Although the terracotta colour is acceptable in most situations (see examples below), the air brick can be painted with any exterior paint, such as Sandtex.



Examples:
6 of the 12 boxes (SB-200's) in the old St Neots factory site in Brook Street
At least 2 boxes were occupied in 2012, and 1 pair bred.

One of the 5 boxes occupied in 2013, chicks were known to be raised in at least 4 boxes
and Swifts were seen entering 9 different boxes.
2 air brick linersin a small development in Colville Rd, Cherry Hinton, Cambridge

Closeup of an installed air brick liner

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