Friday 13 November 2015

Owlstone Road, Newnham, Cambridge

In 2011,  we installed two 4-box Swift cabinets on 2 houses in Owlstone Road, Newnham. As in many places over the years, a street with a vibrant Swift population had been reduced to virtually nothing. The first Swifts probably occupied the cabinet on Pam and Vic Gatrell's house in 2014, but they were away for much of the summer, however in 2015, 2 pairs were definitely in residence, and one of them raised 2 chicks. 

by Dick

Two chicks looking out of the cabinet. Photo Vic Gatrell
Not being satisfied with this, Pam and Vic wanted more boxes. While we could have suggested a second cabinet, instead, we took a good look at the structure of the gable end, and suggested built-in boxes.  

The gable wall is 2 bricks thick, with no cavity and is built in Flemish bond: a sequence of headers and stretchers. Removal of a header makes a hole all the way through the wall. This was relatively easy, as the bonding was soft lime mortar.

Two entrance pieces and their moulds
With previous experience of retrofitting entrances fabricated out of airbrick liners, (here and here), this time we decided to try something different, with entrances cast in a mould using a 50:50 cement/sand mixture. 

The mould was made on a 3D printer. This meant the hole could be made to a fine tolerance, with dimensions 65mm x 29mm on the inside and 68mm x 32mm on the outside. Thus it was slightly tapered, allowing easy extraction from the mould and any rain drops would tend to flow out rather than in.

Casting entrances in a mould is a lot easier than slicing up airbrick liners.

Pam and Vic own the part of the wall
left of centre. Photo Pam Gatrell
Apart from manufacturing the entrances, the only other thing we did was to build the first nest box. We then handed over to Newnham Property Services who fitted all 6 entrances in the wall, built the remaining 5 boxes and fitted them inside the roof-space.

The work also included making a trap-door from an upstairs bedroom into the roof-space.

The end result is very pleasing, and bodes well for the return of a thriving Swift colony in Owlstone Road.

The following pictures should be self-explanatory.

[For Newnham Property Services, contact Marek on phone 0773 137 6154]
6 new entrances; the natural colour of the cement/sand mixture
matches the brick colour remartkably well. Photo Pam Gatrell

Design drawing for the nest boxes. All boxes are fitted with a perspex back.
The perspex is held in place with slots top and bottom and slides out sideways

6 boxes inside the roof-space. Photo Pam Gatrell
#inserts #Cambridge

1 comment:

  1. Perfect! This is exactly what I want to do in my house, and this articlw will make a great guide.