Self-Adhered Modified Bitumen Membranes Make a Splash

Part 1: Managers Search for Non-Asphalt Adhesive

Part 2: Self-Adhered Modified Bitumen Systems Vary Among Manufacturers

Part 3: Installation Insights for Self-Adhered Modified Bitumen Systems

Part 4: Ask the Right Questions When Specifying Self-Adhered Modified Bitumen Systems

Part 5: Snow Presents Danger on the Roof

Self-Adhered Modified Bitumen Systems Vary Among Manufacturers

By Curtis L. Liscum - January 2009

Now comes the development of SA modified bitumen materials. SA sheets generally are modified with styrene-butadiene-styrene (SBS) or SBS-type modifiers. This modification creates a material that is even stickier and more rubbery than normal SBS modified membranes.

The additional stickiness requires the surface to be protected by a release paper in lieu of a parting agent — granular, powder or liquid — as is the case on normal modified bitumen membranes.

Most manufacturers have developed an SA modified bitumen system using two plies of modified bitumen material. The systems vary among manufactures, but the configurations range from both plies being self-adhered to one-ply self-adhered — generally the bottom ply — and the top ply adhered with adhesive or torch-applied.

SA sheets come with self-adhering material on one or both sides. The two-sided materials can help ensure better adhesion between the two sheets of SA membrane in the system.