Should I Have the Rubber Roof Replaced?

Rubber Roof Types

• About 80 percent of rubber roofs in the U.S. are made of ethylene propylene monomer, or EPDM. The remaining rubber roofs are made of modifed bitumen (MB), commonly called asphalt, combined with atactic polypropylene (APP) or styrene butadiene styrene (ABS). Rubber roofs are most often found on the roofs of recreational vehicles and low-slope roofs, which are those with a slope of pitch of 3:12 or less. A 3:12 roof rises three feet for every 12 feet of length. White rubber roofs reflect heat and may last longer in hot climates. The signs that you may need to replace a deteriorating roof are the same for EPDM and APP or ABS modified bitumen.

Surface Loss

• Rubber roofs wear out by slowly losing their surface over time. On houses, they are usually are .040 to .060 inch thick. On RVs, they are generally .040 inch thick. You can shine a flashlight through a rubber roof when it reaches .015 inch thick. Modified bitumen roofs are often covered with granules. As they age, they lose these granules. As rubber roofs get thin, they begin to appear wavy and sag or leak. When these symptoms appear, it may be time to replace the roof.

Cracking and Blistering

• Extremes in weather, prolonged freezing in the winter and searing heat in the summer cause the roof surface to expand and contract. Over time, temperature shifts will cause rubber roofs to deteriorate. Look for blisters, cracking and loss of surface granules. Look especially for cracks around the edges of the roof and around chimneys, flashings and gutters. Cracking may also develop in roof seams. If the cracking and blistering are severe, there is no easy repair, and you should replace the roof.

Ponding Water

• On flat roofs, water forms pools, a phenomenon that roofing contractors call ponding. As these ponds dry out, they leave concentric rings of dirt. In hot weather, rubber roofs may begin to split or form holes as these pools dry out. If a rubber roof is deteriorating from constant ponding, it may have to be replaced.