Project Title: Pembridge House
Location: Notting Hill, London
Wood Species: AMERICAN WHITE OAK
Project Description
This project is the refurbishment and reconfiguration of a mews house in Notting Hill.
In common with many mews houses, bedrooms are on the ground floor with the living areas positioned on the upper floors to take advantage of the light.
A bespoke kitchen replaces one which was previously relegated to a small extension to become a hub between the living space and dining room. The full height panelling of the kitchen continues into the dining space to prevent it feeling isolated from the other areas. The kitchen is constructed from MDF carcasses with an oak veneer and finished with a graphite stain.
A new staircase winds down the side of the kitchen island and comprises a series of solid oak treads restrained to the adjacent wall on stainless steel collars. The glass and stainless steel handrail is independent of the treads.
Staircase Principle
As existing lightweight wall adjacent to the stair made the clients aspiration of a cantilevered stair very difficult.
Inspiration was sought from the many stone cantilever stairs found in Georgian buildings throughout London. Despite their visually impressive lack of edge support where one would expect to see the stringer, the structural principle of these stairs only appears to rely on a cantilever, in reality each tread is supported on the one below.
For our interpretation, oak bats are pinned to the ply skinned wall with stainless steel fixings. Each bat is supported by the bat beneath so that only vertical load is imparted to the ply wall. Using large sections of oak is fraught with problems caused by drying shrinkage. Our concern was that if each tread shrunk by only 2mm the top step would droop by 40-50mm at the tip. Therefore the timber was kiln dried progressively and tested to match its humidity precisely with the target internal humidity. For aesthetic reasons the stainless steel pins were epoxy bonded into the timber at reduced edge distances. Falling short of recommendation by the British Standard for timber the first three treads were made and built and then load tested prior to proceeding with the remainder of the stair.
All treads were French polished along with the timber floor to unify their appearance.
Tread Manufacture
Each individual tread is formed from oak laminated horizontally, with large section on top (ex 77mm x full width) so as to avoid visible joints to top and flat front edge – these were hand picked for the job.
Lower layers are glued in the width and are all ex 38mm thick because this has less splits internally which are produced by the kilning process and we did not want these to manifest themselves on the ends of the treads. Once glued in the width, they were planed to thickness and then all layers were glued together in one operation.
The resultant oak ‘block’ was carefully marked and cut roughly to shape with a chainsaw. The final shape obtained by use of electric planer and belt sander.
Winder treads formed by the same principle but hand finished ‘by eye’.
BUILDING OWNER: DOUGLAS GARISTINA
ARCHITECT: WESTARCHITECTURE
BUILDER/MAIN CONTRACTOR: A. PRICE LTD
STRUCTURAL ENGINEERS: WEBB YATES ENGINEERS
JOINERY: GARY CURNICK JOINERY
