Flat Roofing Materials Compared

There are three basic types of flat roofing materials, although there are variations within the three categories that allow building owners to have more choices. Whether your building is new and this will be its first roof or you are replacing older roofing material, here are the three main categories you will be able to consider. There are inherent advantages and disadvantages of each type.


Built-up bituminous roofs have been the standard for many years. They are still relatively popular primarily because they are inexpensive.

Built-up bituminous roofing is created using layers of hot tar, gravel, a smooth river stone ballast and tar paper or fiberglass membranes. Other than the lower cost, the advantages include fire resistance and some people think the appearance is more attractive.

There are several disadvantages. The material is very heavy. The underlying joints of the roof may need to be strengthened in order to install this type.

The installation itself is messy and smelly. It is not a do-it-yourself job for the building owner.
Once installed, it is hard to find leaks in the material and repairing leaks can be difficult. As time goes by, the gravel can break loose and clog the gutters. This choice is not recommended for buildings that are currently occupied.

Modified Bitumen:

Modified bitumen sheeting has a mineral-based surface to convey the fire resistant benefits of built-up bituminous with less weight. The sheeting consists of a single layer that is rolled onto the roof. The sheeting may be attached using a “torch-down” system, although newer modified bitumen rolls have a peel-off backing that sticks to the existing surface. The peel-and-stick installation can be a DIY project for the building owner.

One advantage of modified bitumen has to do with the light colored minerals that are embedded in the sheets. The minerals reflect heat, which can convey energy savings in areas where summer air conditioning costs are high. This is also an affordable alternative.

The main disadvantage of the torch-down system is the risk of fire. The process is not recommended for buildings that are currently occupied. The sheets are not the most resistant to scuffs and tears. Modified bitumen is considered less durable than the next type.


EPDM is a type of synthetic rubber. It resembles an inner tube but has been engineered to resist damage from sunlight. EPDM sheets are available and can be anchored with fasteners, glued on or ballasted with stones. Liquid Roof is another form of EPDM rubber is also available for waterproofing or coating existing roofs to extend the lifespan of the roof.

The advantages include easy installation and high durability. Rubber is inherently accompanied by a reduced risk of leaking. If leaks do occur, they are easy to locate and repair. There may also be a sound-reduction advantage.

The only disadvantage may be heat absorption depending on the color selected. Lighter colors are recommended for warm climates but may cost more.

Some building owners feel that the cost is a disadvantage. EPDM does cost more than other roofing materials. But because it is more durable and typically lasts longer, EPDM may cost less in the long run.

For product information or ordering visit EPDM Coatings or call them at 855-281-0940.