Specifying modified bitumen sheet products

Options and choices complicate modified bitumen product selection

Currently, there are more than 900 polymer-modified bitumen sheet products available in the U.S. market for use in low-slope membrane roof systems. There are 26 ASTM International standard types and grades for these products. As a result, comparing and properly specifying polymer-modified bitumen sheet products can be challenging.

ASTM International standards

ASTM D5147, "Standard Test Methods for Sampling and Testing Modified Bituminous Sheet Material," provides an industry-consensus method for sampling and testing polymer-modified bitumen sheet products. The standard includes test methods for overall material and coating thicknesses, load strain properties, tear strength, moisture content, water absorption, dimensional stability, low-temperature flexibility, granule embedment, compound stability and low-temperature unrolling.