Thursday, 13 January 2022

External Wall Insulation

With the drive towards zero carbon, external wall insulation (EWI) on older houses will result in the loss of many Swifts and bats, but it is also an opportunity to provide many more nest places. In particular, the S Brick is an easy to install solution for Swifts and other small cavity-nesting birds. [A solution is also needed for bats!]

External Wall insulation is usually anything between 90mm and 110mm thick. It is thus not thick enough to embed a nest box unless it projects outside the insulation, or it is embedded in the outer leaf.

Older buildings will either have solid walls or they will have a narrow 50mm cavity. As the outer leaf is typically ~100mm thick, there is an available depth of at least 190mm for an S Brick. It just requires the removal of 1 brick and replacing it with an S Brick. The internal floor area would be ~440 sq cm, plenty big enough.

The following images and examples show how it can be done:

Palight S Brick for a rendered wall

Section showing S Brick embedded in outer leaf and EWI

S Brick entrance

Example before render [Credit Conwy County Borough Council]

Four S Bricks embedded in EWI [Credit Conwy County Borough Council]

S Brick entrance embedded in EWI - example from Cambridge