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Perthcelyn Community Primary School Rhondda Cynon Taff Property Consultancy

Taking advantage of the sloping site, the school classrooms face east and have glazed facades to give light and view, with smaller rooms accommodated in two levels on the west side. A shallow pitched zinc-covered roof oversails the classroom facade, rises to a continuous rooflight at the east side of the ridge and slopes down to the west wall. The walls are of timber-clad or rendered blockwork with full cavity insulation.

A series of glulam rafters and purlins form the roof structure. On the classroom side this comprises paired glulam rafters at 3m centres, braced with tie-rods and resting on columns set just inside the glazed facade. They give support to 200 x 80mm purlins and counter rafters; the space between them gives ventilation below the boarded zinc roof covering.

Zinc was chosen for its ability to accommodate the complex roof planes. The pre-patinated 600mm x 0.7mm rolls, made by Rheinzink, were machine- crimped on site and jointed with standing seams.

The concept - to extend the roof beyond the east and west walls as a delicate leading edge - raised problems; how to reduce the thickness of a well-insulated roof covering, and how to deal with rainwater drainage. The solution was to set the gutter back from the edge and enclose the rainwater downpipe between paired fins fixed between the window frames. The roof beyond the gutter, no longer requiring insulation, could then taper to a delicate edge.

On the east elevation the rainwater pipes are set in from the verges. At gables the zinc gutter stop is extended beyond the edge of the verge to give it definition. The verge is clad with zinc.

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