Single-Ply Waterproofing Membranes

These waterproofing products include polyvinyl chloride (PVC), ethylene propylene diene terpolymer (EPDM), and isobutylene-isoprene rubber (butyl). The products are supplied as rolled sheets; sheet laps are sealed in the field by adhesive or heat welding. These materials are subject to the following waterproofing standards.

• ASTM Specification for Vulcanized Rubber Sheets Used in Waterproofing Systems (ASTM D 6134), Type I (EPDM); and Type II (Butyl)

• CAN/CGSB-37.54-95 Polyvinyl Chloride Roofing and Waterproofing Membrane, Reinforced with Embedded Fabric, Waterproofing (CAN/CSB-37.54-95) Type 4, Class C

• CAN/CGSB-37-GP-52M Roofing and Waterproofing Membrane, Sheet Applied, Elastomeric, Re­inforced Membrane, for Non-Exposed Use (CAN/CGSB-37-GP-52M) Type 2, Class В

Bentonite

Sodium bentonite (bentonite) is a high-swelling form of weathered volcanic tuff. It takes its name from Fort Benton, Montana, where a deposit was discovered. Bentonite swells in the presence of water, and, when confined—for example, by an overlaying concrete slab—the hydrated bentonite forms a dense, flexible layer that stops the passage of liquid water. While there is a long history of use of the product as a waterproofing material, we are unaware of a material specification standard describing bentonite as a waterproofing material.