High-strength built-up roofing using improved ply sheets

摘要

Lighter weight, high strength, built-up roofing (BUR) membranes, systems and process for obtaining same are provided herein. These BUR membranes are made by using an improved ply sheet having uniform ventability and attachment in the overall assembly and superior resistance to wind uplift. The improved structure involves a ply sheet carrying 1/8 inch diameter or larger perforations along its longitudinal border in an area comprising between 1/5 and about 1/2 the width of the ply sheet. The ply sheets here employed for the BUR assembly or membrane have a thickness essentially not in excess of the layer of bonding agent applied over each ply in the assembly.