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The Bodmin Jail on the edge of the Bodmin Moor in Cornwall was originally built by military engineer John Call during the reign of King George III in 1779, as part of the ground-breaking Prison Reform. The buildings in their current form were completed by 1881. The later 19th century saw part of the site transferred to the Admiralty, and the Bodmin Royal Naval Prison was established by 1887. The building is statutorily listed as Grade II and has been renovated as a luxury 70-bedroom boutique hotel and a museum.
Over the course of history, the roof structure and slate have suffered significant degradation, which has given Mallino Developments Ltd. the challenge of immediate renovation. Twelve Architects, a London-based firm are behind the design of the hotel, while the main contractor C Field Construction and engineers ARUP Group turned the design into reality. Close attention was paid to the design aesthetics required to achieve a contemporary-looking roof structure on the historic building.
Riverstone Ultra slate was accepted by the Cornwall Council Historic Environment team because of its similarities with indigenous slates, Delabole and Trevillet. The slates were dry laid by Stuart Wheeler Roofing Services Ltd at a 200mm gage and a 100mm head lap in even courses, using modern construction techniques including felt batten and copper nail fixings in order to protect the fabric of this historically important building and avoid excessive wind uplift.
Riverstone Phyllite offers a unique appearance to the roof. It is a medium grey colour, with slightly coarser grain and a unique satin-like luster due to the prolonged heat and pressure exposure. With comparison to Delabole slate, Riverstone is considered to be stronger and provides better longevity as a roof covering material. This extra length of time in the ground has evolved the original slate structure in such a way that its technical credentials – exceptionally low water absorption and durability – are second to none. It has achieved the highest classifications in the UK market. SSQ offers a lifetime 100 - year guarantee for Riverstone Ultra.