To address the problem of a deteriorating barrel vault roof and associated flat roofs, Cumberland School in the London area of Canning Town now features the Derbigum waterproofing system from Alumasc Exterior Building Products. This system incorporates enhanced performance properties such as increased flexibility, stronger reinforcement, and an improved fire rating. Almost 1700m? of the product was installed on the school, over Alumasc?s Hi Ten vapour control layer, Korklite Plus insulation and specially 'scored' polyurethane to accommodate the curved roof. While it needs no surface finish, Derbigum may be painted and can be specified with one of five mineral facings.