Buxton Associates were employed as a structural engineer on an owner driven speculative roof top development on a group of 1930’s mansion blocks in Worcestor Park, Surrey.
The existing buildings have solid external walls, concrete floors and a timber mansard roof. The proposals allow for the replacement of the roof with a new singe storey of accommodation. The mass of the existing building is quite high and so we proposed the use of a timber framed structure to form the new floors, walls and roof.
This approach kept the new loadings down to well within the allowable for the existing masonry walls. We used the external walls to support the roof and the flat party walls and cross walls to support the new floor structure.
We worked closely with the architect and contractor to develop an attic truss, timber framed solution. The new trusses comprise the roof, front and rear elevation and floor structure. Each truss is relatively light and so a group can be lifted up to the existing roof by mobile crane and then be simply manhandled into position.
The introduction of dormers and bays led to slightly more complexity in the truss arrangement but the basic principle of lightweight, easy to manoeuvre structure is retained in the final design