Common Issues Seen with Modified Bitumen Roofing and How to Avoid Them

Modified bitumen roofing has been around since the 1960s and is one of the most popular and common roofing options seen on commercial and other low slope roofs in North America. While the main ingredient of modified bitumen roofing is asphalt, it doesn’t much resemble asphalt road materials. With the addition of modifiers like APP (Astatic Polypropylene) or SBS (Styrene Butadiene Styrene), this roofing material has a plastic or rubber-like quality and comes in rolls for easy installation. It can be smooth on the surface or have added granules (often aluminum or copper).

When properly installed and properly maintained by trained roofing professionals, modified bitumen roofing is long-lasting and has some of the best warranties in the roofing industry. However, no roofing material is perfect. Here are some of the most common issues seen with modified bitumen roofing:

  • Failure along a seam: Seams most often fail due to poor or improper installation techniques. The failure of a seam can also be caused by the thermal expansion and contraction that occurs during extreme temperatures.
  • Moisture damage: While moisture doesn’t usually penetrate this product, if it does, it can cause blistering that cannot be repaired. Sections with blistering must be replaced, but even more importantly, the underlying cause of standing water must be addressed to avoid future issues.
  • Punctures: If punctures are small, they can be sealed easily. The most common cause of punctures is excessive foot traffic. Access to your roof should be limited.