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GAF May17

Did you know that 98% of all roof repairs occur in penetrations or perimeters – meaning anything that protrudes through the roof or breaks the membrane? Some examples include curbs, drains, plumbing stacks, vent stacks, elevator shafts, antennae bases, electrical and copper lines, skylights, and penthouses. These areas present challenging repairs, and if they’re not done correctly, could result in a leak.

Here are some examples of what not to do on a roofing job:

  • Don’t use non-compatible roofing materials. For example, using plastic cement on single-ply membranes.
  • Don’t overspray with coating. Doing could leave you with an insurance liability claim on your hands.
  • Don’t cover electrical cords/conduits. These areas will need to be accessed at some point.
  • Don’t clog drains. Keep them clear so they don’t lead to ponding on the roof.
  • Don’t just poke a hole in the roof and put goop around it. Besides the fact that it doesn’t look very nice, it won’t be watertight.

There are many solutions for tough penetrations. Whichever one you choose, be sure to use a high-quality sealant to ensure correct waterproofing. Here are three methods a contractor can use to waterproof a challenging penetration:

  1. For an MB or BUR roof system, seal using the three-coursing approach. That includes placing one layer of sealant, one layer of fabric, and one layer of sealant. The final step is to sugar-in matching granules with the SBS or BUR surface. The advantages of this approach are that it’s easy to use, no mixing is needed, and there is less waste, as the pouches are reusable.
  2. For a metal roof or MB or BUR roof system, use TOPCOAT® FlexSeal™ Elastomeric Sealant. It is a similar approach to three coursing but uses a different sealant. It is compatible with metal, concrete, wood, SBS, APP, EPDM, and BUR substrates for gutters, detail areas, edge metal, and termination bars.
  3. For a BUR or MB roof system, use an M-Curb™ Pitch Pocket System, which is made from solid urethane and designed to seal difficult penetrations on asphaltic roofs that can’t be flashed. This option requires no fabric or granules, as the material is pourable and bonds with the asphalt roof. Installation is fast and easy, and these curbs are very versatile, as they can be made in custom shapes to fit a variety of rooftop places.

Liz Barth is a writer with GAF ProBlog. Read more at www.blog.gaf.com and discover additional maintenance ideas through GAF’s technical advisories.


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