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Modified Bitumen

Modified Bitumen roofs, also called ‘mod-bit’ roofs, are flat roofs that do not require shingles for protection against the weather. Modified bitumen (MB) is a product that was engineered for use in Europe in the 1960s and has been successfully adopted for use in Canada since 1975. MB is asphalt with added modifiers mixed into it that creates a waterproof roof sealant with plastic or rubber characteristics. MB comes in rolls of 36 inch or 39 inch and covers approximately 100 to 112 square feet per roll, which means there will be very few seams in between sheets. Usually mod-bit roofs are one ply systems, meaning only one sheet of MB is applied to the surface of the roof, but two and three ply systems do exist and are called hybrid systems. There are two types of MB membranes, SBS and APP. SBS membranes are the most common and require ‘hot-mopping’, or torching, of hot asphalt during application. However, self adhesive SBS membranes are gaining popularity because they require the ‘cold-process’ for installation. This process eliminates the need for torches, hot asphalt, and is free of volatile organic chemical fumes that are released during and after the application of a mod-bit roof. There are a variety of surface options for flat roofs today that there hasn’t been in the past. Gravel and mineral surfaced membranes traditionally came in white, but today are available in an array of colours to match shingles and compliment the design of any home. There are also mineral and gravel ‘cool roof’ membranes available that have a special coating to reflect light and reduce cooling costs.

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