Mod-bit roofing is a shorter way to say modified-bitumen (MB) roofing. MB roofing systems are a durable, weather resistant type of low-slope roof.
Mod-bit materials are sold in rolls, and its seams are sealed using heat (the common open flame torch), hot- or cold-applied, or self-adhering. The base sheet that the roofer mechanically attaches to the roof deck with cap nails or disc plating ensures excellent protection from wind uplift.
Next, the base ply overlap is sealed with a watertight adhesive. The final surface layer in typically granular but there are smooth options as well. Like built-up roofing (BUR), it is usually installed on low-slope and “flat” roof structures. Application of this type of roofing is less labor intensive than the built-up roofing method that applies several layers to create a waterproof membrane. Modified bitumen roofs have been used in the U.S. since the 1970s.
Two additives can be added to MBs that alter the structure/pliability slightly, APP (atactic polypropylene) and SBS (styrene-butadiene-styrene). APP gives strength to the roof without sacrificing flexibility and is sealed through heat welding, while SBS results in a more “rubber” type membrane with a base that requires nailing it down before covering it with self-adhering membranes, mid-plys, and cap sheets.
Although there are layers involved in mod-bit roofing because of the base sheet or recommended underlayment, it is considered a singly-ply, not a built-up roofing system. This form of roofing does not eliminate the need for insulation or proper drainage.
While it’s a reliable roofing system, most manufacturers of the products and this process warrant its life at about ten to fifteen years.
At Anderson Contractors, we are well-versed in all types of roofing systems. We take the time to assess each project individually and decide the best roofing materials for your business. Call us today, and we can review your options with you.