What Is Modified Bitumen Roofing?

Diane Stevens

Developed in Europe in the mid-1960s, modified bitumen roofing has been used in Canada and the United States since about 1975. It was developed as a means to improve roofing membranes when product quality was affected by the use of a lower-quality crude oil by-product.

Modified Bitumen Roofing

Modified bitumen roofing is a roofing asphalt. Materials, such as layers of fiberglass or polyester, are added to the asphalt to add strength to a flat roof.


Modified bitumen was developed because oil refineries had figured out ways to use more products from crude oil. The resulting asphalt by-product was of lower quality. To improve the performance of the asphalt, the manufacturers modified it with rubbers or plastics and then bonded it to fabrics made of fiberglass or polyester.


Modified bitumen roofing was designed for use on buildings that have a low slope or flat roof.


There are a wide range of methods available for installing modified bitumen roofing, from using a hot torch to using a sealant-backed peel and stick rolls. Modified bitumen roofing has excellent waterproofing features, and the cost of installation is competitive with other materials when compared on product lifetime. Modified bitumen roofing has high tensile strength and, in general, has excellent weather resistance.