A modified bitumen membrane roof is tough, tear-resistant and long-lasting when properly installed and regularly maintained. It’s a great choice of material for your commercial building. If your building currently has a modified bitumen roof, then this article is for you. The more you know about your roof, the more you’ll be able to take care of it. In this article, BFARR Contracting, one of the leading roofing contractors in our local area, discusses some of the things that professional roofers focus on when inspecting modified bitumen roofs.
Flashing
Flashing details on a modified bitumen roof must be able to withstand the forces of nature and remain watertight while still being able to move with the stresses. Detailing flashing requires careful thought throughout the design and installation process. There are nearly endless amounts of possible flashing errors on a flat roof. That’s why we always focus on inspecting flashing during our roof inspections. Gaps in the flashing are some of the most common causes of roof leaks.
The most important thing to remember about flashing is that there should be flashing anywhere the field of the roof membrane stops or is interrupted. If there is a vertical interruption such as a wall, then the field membrane should turn up and then have a base flashing over it. This base flashing should be of the same type of material as the field membrane and it shouldn’t be metal.
Metal flashing should only be used around the perimeter, on flanges of roof penetrations, on water-shedding counter flashing, or to protect the roof from mechanical damage. Metal flashing can also be used for decorative reasons. A good roofer must remember that roof cement and fabric are not adequate substitutes for base flashing and counter flashing.
Perimeter-Edge Flashing
During our inspections, we will carefully inspect the perimeter-edge flashing because this is one of the most common failure points on a modified bitumen roof. Sometimes the metal-edge flashing in this area is not cleaned and primed with an asphalt primer. This causes the membrane to lose its adhesion to the metal flashing. All metal flashings must be mechanically fastened down, cleaned and asphalt-primed to prevent this from happening.
In addition, the perimeter flashing should also be sandwiched between the roof field membrane and a top cap sheet or a strip of membrane. Lots of times, the field membrane is improperly sealed over the perimeter-edge flashing. A good professional roofer always carefully checks the seal at the perimeter flashing. If you are constantly searching the internet for repair my roof and getting your roof repaired, then installation mistakes like the ones we mentioned above might be the reason.
Vertical Angles
When installing a modified bitumen roof, the installer must avoid 90-degree vertical angles in the membrane. These 90-degree bends are prone to leaking and cracking. In addition, any vertical angle that’s more than two inches high must have a “cant strip.” This is a triangular strip made of wood, fiberboard or Perlite. It allows the base flashing membrane to make a 45-degree instead of a sharp 90-degree turn.
Mechanical Equipment
Heavy equipment should sit on a flashed curb or on a steel frame with angle iron legs that penetrate the roof and not on a 4”x4” or other similar material. Mechanical equipment should never sit directly on the roof membrane because the equipment can damage the roof. The vibration of the heavy equipment causes it to cut into the membrane, leading to a roof leak.
You can rely on BFARR Contracting for all of your commercial roof repair, storm damage restoration, roof replacement and roof maintenance projects. We have built a reputation for first-class workmanship, great products and outstanding customer service. We work hard to exceed our customers’ expectations because we focus on building long-term business relationships. You can count on us for all of your roofing needs. Call us at (321) 444-6446 to learn more about our services and products or to get a free estimate.