is a type of waterproofing system for buildings. It is used on flat or nearly flat roofs to prevent leaks and move water off the roof. Membrane roofs are most commonly made from synthetic rubber, thermoplastic (PVC or similar material), or modified bitumen. Membrane roofs are most commonly used in commercial application, though they are becoming increasingly more common in residential application
A modified bitumen membrane roof is a system developed by taking the qualities of a BUR system along with the qualities of a single-ply roof. A standard MBS roof system should have a base sheet or ply, similar to the BUR system, then a waterproofing sheet similar to single-ply.
To break it down, a modified bitumen membrane is composed primarily of polymer-modified bitumen reinforced with one or more plies of fabric such as polyester, fiberglass, or a combination of both. Factory surfacing, if applied, includes mineral granules, slag, aluminum, or copper.
Modified bitumen's generally use a traditional waterproofing medium -- asphalt -- modified with atactic polypropylene (APP), styrene butadiene styrene (SBS), synthetic rubber, or other agents that will enhance the asphalt properties. APP and SBS are the most common bitumen modifiers.
is a thermoplastic polymer, which forms a uniform matrix within the asphalt. This enhances the bitumen's performance by increasing its UV resistance, increasing its flexibility at low temperatures, and improving its flow resistance at high temperatures. APP modified bitumen sheets are generally applied using a propane-fueled torch. We use the heat (torch) to soften the modified bitumen on the underside of the sheet. The sheet's bottom surface becomes a molten adhesive, which flows upon the substrate and then cools to form a waterproof adhesive bond. Some APP sheets can also be applied with cold-process adhesives