What Do You Think of a Flat Rubber Roof?

Characteristics

• The biggest problem with flat roofs is their inability to efficiently shed water and snow the way sloped roofs do, so they often don't last as long as sloped roofs. The wood framing beneath flat roofs is more vulnerable to rotting, because it takes a non-sloping surface longer to dry out. Even small sections of flat roofs above porches and garages are vulnerable to rot. However, rubber roofing products have helped make flat roofs more durable.

Ethylene Propylene Diene Monomer

• Several home improvement publications note the benefits of ethylene propylene diene monomer for flat roofs. For example, "This Old House" magazine writer Max Alexander describes EPDM as a rubber membrane that creates a smooth, strong surface on a flat roof. EPDM also resists damage from water and direct sunlight, and an installer can glue it to the roof's surface or attach it with fasteners. Alexander notes that do-it-yourselfers can install EPDM, because it's easy to handle, and any leaks that develop over time are easy to patch.

Installation

• Some rubber roof membranes are made of synthetic rubbers and others consist of polyvinyl chloride plastics, according to "Ask the Builder" online columnist Tim Carter. Carter indicates that both synthetic rubber and PVC types typically last a long time, and some come with warranties of 20 years or more. Installers can use large pieces of rubber membranes to avoid creating seams where water might seep in, unless seaming is necessary to work around a chimney or heating vents. Alexander indicates that uncured rubber can be formed into collars that surround the bottoms of vents and chimneys to prevent leaks at seams. Uncured rubber will cover without springing back and leaving a seam vulnerable to water seepage.

Considerations

• Carter estimates that the cost of installing a rubber membrane ranges from $250 to $400 per 100 square feet, if the removal of other roofing materials isn't required. Rubber membranes are usually black, which means they absorb heat that could drive up your cooling costs during summer months. Alexander estimates that applying a light-colored coating to the rubber to avoid heat absorption could drive up installation costs by 30 percent or more. Another drawback of rubber roofing is that it's vulnerable to being punctured by debris or other objects in severe weather.