[WORKING DETAIL 04.03.10] Timber-clad fin and eaves details
Fitzwilliam College Library and IT Centre − Structural timber cassettes make up the saw-tooth west elevation, with curtain walling between. The cassettes, which replaced the original composite insulated Metsec panels during the construction design period, were constructed from sustainable timber (high-performance Bitroc externally, OSB internally) with Warmcel insulation (manufactured from recycled newspapers), a build-up which provides high levels of airtightness and low U-values. The cassettes were fabricated off-site, allowing for rapid installation.
The elevation is clad with fine-sawn air-dried European oak boards with 10mm shadow gaps, which are untreated, so they will weather to a silver finish and will require no maintenance. The vertical boards emphasise the vertical rhythm of the elevation, with a joint to articulate first-floor level.
The boards are supported by battens and counter-battens, with a fly-mesh layer between. They have double fixings at 600mm intervals. In discussion with TRADA (the Timber Research and Development Association), the fixings were designed to allow movement of the natural material, using button-head stainless-steel screws in a 2mm oversized hole. The screws are recessed, so the head is flush with the timber face. The cantilevered ends of each fin are supported with glulam sections fixed back to the cassette.
Internally, bespoke timber and marmoleum desks are fixed to the timber wall, allowing each desk to be naturally lit from the side. Above the timber and glass saw-tooth, a lower roof cantilevers out from second-floor slab level, providing shade from direct sunlight.
It is supported off the in-situ concrete upstand with a metal frame, which is thermally broken at the building envelope. The roof is finished with standing seam preweathered zinc, with a concealed zinc gutter formed in front of the window line. The soffit is finished with Douglas fir battens with shadow gaps. A PPC steel angle with secret fixings gives a clean edge to the roof projection.
Lucy Spencer, project architect, Edward Cullinan Architects
Curtain walling Technal MX Trame horizontal and vertical curtain walling
Windows Technal FXi65 aluminium window system to reader tower
Glass North and east elevations 8mm toughened, cavity, 10mm toughened top N+ (low-e); south, west and reader tower 8mm Vision 60T, cavity, 10mm Planibel Clear
Brickwork Ibstock Crowborough multicoloured stock; quarter lap stretcher bond to reader tower; stretcher bond to east elevation; header bond in half-bat bricks to south tower
Zinc roofs Rheinzink preweathered pro blue-grey unventilated standing seam on Enka-Vent underlay and composite panel
Ceilings Armstrong Ceilings
Blinds Claxton Blinds. MechoShade roller shades
Sanitaryware Armitage Shanks
Internal doors American white oak
Window boards American oak-veneered MDF
Ironmongery Satin stainless-steel finish
Handrails American white oak
Balustrades PPC steel
Signage to main circulation and library areas Brushed stainless steel
Static and mobile shelving Rackline
Acoustic ceiling British Gypsum CasoLine MF suspended ceiling system to entrance and top floor