Sam Tisdall Architects reconfigures 1920s semi-detached cottage in Cambridge

Architect’s view

There were two elements of the scheme which were considered in particular detail.

The first was the external cedar cladding. Originally proposed as more traditional cladding, with the encouragement of the client it developed into a more refined rainscreen of 90mm-wide cedar battens with 10mm gaps. Behind this, there is a UV stable black breather membrane to the walls and a single ply membrane to the roof. By using a rainscreen we were able to detail gutters and eaves with no flashings or copings. To fix cladding to the roof proprietary fixing bars were used. These are typically used to fix solar panels and can be welded to the roof membrane which is continuous underneath. Careful attention was paid to setting out so the windows coordinated with the cladding, with no cut boards.

The second element was the new staircase. Made from solid Douglas fir, it required careful detailing to hide the fixings of the blackened mild steel handrail and close co-ordination between joiner and metal worker. Pre-finished sections of handrail were slotted into place through rectangular holes drilled in each tread. Each spindle was then fixed to a set-back cut stringer and the stair edge clad with an MDF fascia. The sections of handrail were then welded together to form a continuous handrail and the blackened finish touched up. This process traditionally called blueing is used for blackening weapons (think black revolver) and is achieved with a mix of chemicals which the metal worker had to learn how to use to get the correct effect.

The staircase continues up to the loft to a landing which bridges over the stair void with a double-height space beyond. This allows light from a large fixed window down to the first floor as well as giving a sense of space.

Sam Tisdall, partner, Sam Tisdall Architects