Two-ply roofing felt with polyester nonwoven base and EPDM rubber top - the elongation of the substrate being longitudinally and transversely dissimilar to accommodate excessive temp. variations

摘要

Roofing felt comprises a laminate whose base ply is a polyester fibre fleece and whose top ply is a EPDM elastomer. The fleece is elastic and compressible across its width, its longitudinal elongation being less than its transverse elongation. This serves to compensate for the difference in the coeffts. of thermal expansion between top and base plies, thus ensuring that the roofing felt will lie flat even under extreme temp. conditions. The fleece may be perforated. The top ply is suitably fitted with an additional polyester fleece edging for facilitating overlap bonding of adjacent webs. The overlap is sealable by means of a weather-resistant pasty sealant.