Action for Swifts: Idea for a retrofit internal Swift box

This is a temporary page, which may end up as a published post, depending upon how the idea evolves further.

Over the last few years, Bill Murrells and I have implemented a number of Swift boxes internally (>40 boxes). These have mostly been in gable ends at roof space level. The ideas were inspired by the very successful project at Fulbourn, Cambs, where, in 2016, nearly 90 pairs of Swifts nested in plywood internal boxes.

Some of these projects are in solid Victorian walls where the wall is penetrated by removing a header.

Others are in more modern cavity walls with a 100mm cavity. All of them involve a neat entrance piece in the outer wall with a nest box spanning the cavity and the inner leaf, or wholly inside the roof space accessed via a 100mm pipe (as in Fulbourn and in Michael Osborne's project). This has become known as "The Cambridge Swift Box System".

Our retrofit internal boxes look nice from the outside. Apart from my own house, they all penetrate the inner leaf. The reason my own retrofitted boxes are confined to the cavity and outer wall is that there is no access to the roof space.

If one were to get a professional to install these boxes, they would be quite expensive.

Since then we advised on the Manthorpe Swift Brick where the requirements were to not penetrate the inner leaf, low cost, easy to install and looking OK in the wall. We think we achieved that - let's hope the Swifts like them.

However, the Manthorpe Swift Brick is designed for new build, for retro fitting it would require the removal of 5 bricks which would be difficult to put back neatly: one slightly odd looking brick in a wall looks OK, several in a group can look a bit of a mess.

When we built the nesting chamber in my own cavity wall it was rather complicated and fiddly, so not really scalable

So, Bill and I have come up with an idea for a retrofit, requiring the removal of just one brick. The box is made out of 2 pieces of folded PVC plastic 1.5mm thick with a cast concrete entrance piece and an optional 5mm cement fibre-board floor - this is rough and absorbent.

The whole thing is easy to make.

The holes in the upper piece are there so that superglue can be squirted into them to secure it, once everything has been fiddled into place.

With standard bricks, the floor area would be over 380 sq cm (~22.5cm x 17cm), more than some commercial boxes. The headroom in the outer leaf would be 75mm, rising to 120mm in the cavity (80mm and 125mm without the fibre board).

This is the simplest that we have managed to come up with. Of course, it is possible that Swifts would readily accept 75mm headroom across the whole box - we do have Swifts nesting in such boxes (2 pairs), but until such time as we have more information, we have gone for more headroom in the cavity.

When we are happy that we have got it right, we have 2 projects to try it out (2 more boxes in my gable is one of them)

We think that risk-averse house owners might prefer this solution to something that goes all the way through the wall, and we think that this is simpler.

Constructive feedback would be welcome - would you stick such a thing in your house?

The following is an animation of how it is assembled.