Modified Bitumen
This class of roofing material is the second most popular material installed and includes various types of membranes to choose from and application techniques. Asphalt based low-sloped roofing represents 19% of commercial sales throughout the country and Statewide Roofing has installed about the same percentage of modified bitumen roofing systems. Modified bitumen membranes are pre-manufactured hybrids that use the same traditional installation techniques used in built-up roofing. These materials are factory fabricated layers of asphalt and reinforcement, “modified” with ingredients for increased flexibility, strength and stability. 
The modified bitumen market consists of two different primary modifiers and the industry uses these acronyms to describe them:
APP (atactic polypropylene)
SBS (styrene butadiene styrene)
The type of modifier used may determine the method of sheet installation; APP’s are applied with an open flame torch and SBS’s are typically applied in hot asphalt or cold adhesive. Each manufacturer could have well over 50 products to choose from with various combinations to achieve the desired performance.
Beware of contractor’s offering one product in a single-ply application.
The modified bitumen roof systems typically consist of 2-3 plies with the cap-ply either having a granular surface or a smooth surface finished with a coating for UV protection. The granular surface is offered in various colors similar to the asphalt shingles you would see on your house. If you choose the smooth cap ply and coating option, the coating should be installed within 60-days and maintained throughout its life expectancy.
The 20% of market share of this product installed by Statewide Roofing is typically in the specified public/municipal sectors as the labor to install 2-3 plies plus the additional material cost involved is easily substituted with single-ply product with no disadvantage to the building owner in terms of performance and longevity.
Advantages:
10 to 30-year non-prorated warranties available through the manufacturer which include both material and labor.
