Reconditioning corrugated roof coverings - by laying on top corrugated e.g. GRP sheets with same wavelength but smaller height so that gaps are formed between them at trough areas

摘要

Corrugated roof coverings, and asbestos cement types in particular, are reconditioned by laying on top corrugated plastic sheets, in which the wavelength coincides with that of the original coverings so that the crests of the sheets rest on those of the covrings whilst gaps remain between the two layers at their troughs. Pref. material for the plastic sheet is GRP. Rafters (1) and purlins (2) carry asbestos cement corrugated roofing (3). Existing fixings to the rafters (1) are used to attach the plastic sheets but they are usually replaced. The applied plastic sheets (4) have the same waves as the asbestos cement but with shallower height. The sheets (4) only rest on the asbestos cement at its crests (5), leaving spaces (7) above the troughs. The spaces have an insulation effect. ADVANTAGE - The method has minimum cost. Roof has long service life, at min. cost.