The ‘Big School Kitchen’ (BSK) at Clifton College in Bristol is a Grade II listed, three-story dining hall and kitchen, built in 1862. The works involved the refurbishment of the whole building, including the roof, which were essential to protect the historic ceiling beneath. The BSK had not been re-roofed since it was built in 1862 so local planners insisted the roof slates be replaced like for like, with Welsh slate.
Complexity
The 1,000 sqm roof covering needed to be stripped and renewed in a phased approach to maintain weather tightness and ensure the ceiling inside was not left exposed to the elements. Roof features included 20 dormers, 100 m long open rafters, plus pitches of approximately 60° and significant amounts of lead detailing.
As many of the original slates as possible were salvaged and some used to re-roof the lower level ‘quad’ roof as part of a larger project to update the college refectory facilities, which is located within a Conservation Area. The team also repaired the stone chimneys and replaced all the leadwork and introduced 50 mm insulation slabs between the rafters to improve the roof’s u-value.
Workmanship
A total of 15,000 of Welsh Cwt y Bugail Dark Blue/Grey rectangular slates and Penrhyn Heather Blue Arrowhead slates were fitted on the duo-pitch roof in the distinctive ornamental pattern of four alternating bands of five rows each, which were twice nailed with copper nails.
The ornamental slates were cut by hand to a design and dimension which exactly matched the existing shaped slates. Prior to new felt and battening, the rafters were treated with preservative spray and restraint straps introduced to prevent future lateral movement.
Build-up
Welsh Cwt y Bugail Dark Blue/Grey natural slates; Natural Welsh Slate Penrhyn Heather Blue Arrowhead slates; Proctor Roofshield breather membrane; BS 747-type 5U heavy duty eaves felt; 50 x 25 JB Red battens; Dreadnought two and three-hole crested clay ridge tiles; Rockwool Flexislab insulation; BLM milled lead.
At a glance
- Project: Big School Kitchen
- Roofing Awards 2019: Roof Slating Winner
- Location: Bristol
- Roof Covering: Welsh Slate; Clay ridge tiles
- Client: Clifton College
- Roofing Contractor: M. Camilleri & Sons Roofing Ltd
- Main Contractor: Kitto Construction Ltd
- Architect: Nichols Brown Webber LLP
- Awards Sponsor: CUPA PIZZARAS
About M. Camilleri & Sons Roofing
Camilleri & Sons Roofing Ltd is a specialist slating and tiling contractor, which offered an award-winning service. Other disciplines offered include all leadwork associated with the roof coverings, cedar shingling and singly ply roofing.
