Why is my Roof Failing at the Seams?

We all want to think that when we hire a contractor, they will know what they’re doing.  Unfortunately, someone may look good on paper, but that’s not the whole story.  The contractor will usually rely on installers. If the installers don’t know what they’re doing, then whatever the contractor promises has no value. A badly installed roof membrane is a guaranteed problem.

Which roof membranes are at a greater risk of Seam Failure?

  • TORCH DOWN: These are thermoplastic membranes that seal by heating the back side of the membrane until it melts and fuses.
  • RUBBER EPDM: A single ply membrane that can be glued or taped on.
  • MODIFIED BITUMEN: Also known as BUR, can be sealed with either hot asphalt or cold adhesives.

Why do roof membranes fail?

  • WEATHERING: UV is a mean mistress… it will eat away at the roof. Rain, snow, and everything that a roof must stand up to, will cause shrinkage, brittleness, and in general slowly deteriorate the membrane.  This is normal and expected.
  • IMPROPER INSULATION INSTALLATION: Insulation needs to be secured to the roof. If not, it will warp and create a hump under the membrane.  This in turn will pull on the seams and will also cause tears in various places.
  • BAD INSTALLATION: When the seams are not sealed correctly, you literally leave an opening for trouble. Just because the membrane seams may overlap, it does not mean they are sealed.

When installers do not have the experience and knowledge necessary to properly install a roof membrane, they will forget key steps. There needs to be a certain amount of weight applied with a roller, the temperature that the melted membrane backing must reach, test strips, and many other details are critical.  It may look good when newly installed… but wait for it! See what happens when it’s put to the test.

Water will travel the path of least resistance. This also applies to layers that are not fused together. Water never “sits” it travels. You should be able to see the line where the seams were fused, but never be able to separate the overlapping layers.


Hire a professional whose installers are just as qualified as he is.  Don’t settle for hiring the face of a company. Hire the company that can back their work with expertise and a real warranty. We at Flat Roof Pros offer a 20 year Workmanship Warranty in addition the Manufacturer Warranty because we stand behind our work. Our Work Speaks for Us. Give us a call for an inspection today.

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