A housing scheme with external service risers
The four-storey apartment block is built of load-bearing masonry with concrete hollow-core plank floors on upper levels.
The courtyard elevations are clad with horizontal western red cedar boards, and a precast concrete deck walkway runs at each floor level to give access to individual dwellings.
All services, including district heating, rainwater and sewage discharge, electricity, gas and water mains, are organised into a series of service risers that run the full height of the building through cut-outs left in the deck walkway units. The risers contain electrical and mechanical services alternately, so that each flat shares a right and left-hand side portion of the adjacent riser.
The risers give external access for maintenance and replacement of services without disturbing residents and are sized to accommodate cabling of future service installations, such as a rooftop photovoltaic system.
The service risers and their doors are clad with western red cedar to match the adjacent walls. The reveals are lined with 12mm fire-resisting board to 1,100mm on the inside, and all cedar is finished with Class O fire-retardant coating. To avoid excessive on-site drilling, precast concrete service blocks with pre-positioned holes (see service riser detail, right) were built into the cavity walls, with a precast lintel above, to direct services into the flats.
The deck walkway units incorporate cast-in conduit for bulkhead lighting. They rest on 152 x 225mm T-shaped beams:
on the inner side these are bolted to the floor planks with L-shaped steel saddle brackets; on the outer side they are bolted to 150 x 100mm RHS columns. Exposed 150 x 90mm PFCs span between the RHS columns to stiffen the walkway edge and to form a frame to the steel balustrades.