Up on the Rooftop
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Up on the Rooftop

The next time you walk outside, take a moment to gaze up at your roof. What do you see? Do you see even shingles that are all laying flat? Or do you see shingles that are starting to curl and that are covered in moss? You can tell a lot about the condition of your roof just by looking at it. If you are at all concerned about the state of your roof, then your first call should be to a roofing contractor. They can evaluate the situation and recommend repairs or replacement as needed. Learn more about roofing and roofing contractors here on this website.

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Up on the Rooftop

A Guide to Commercial Roof Shrinkage

Lori Silva

Many commercial flat roofs are made from EPDM, a synthetic rubber membrane that provides a strong and durable roofing option that can survive for many years with proper care. Unfortunately, there is one issue that can be a major concern on these membrane roofs: shrinkage. The following guide can help you understand why shrinkage occurs and what you can do about it.

1. Causes

Weathering in one form or another is the general cause of shrinkage. UV radiation and exposure to the elements cause the EPDM to lose elasticity and then cause the edges to shrink back and reveal the substrate beneath the membrane. Shrinkage first becomes obvious around the perimeter of the roof and in areas where the membrane abuts against rooftop items like vents and flashing. Moisture then seeps beneath the edges of the membrane, causing leaks and resulting in even quicker deterioration of the roofing membrane.

2. Prevention

Prevention is preferred to repair. Proper installation is the key to preventing most shrinkage issues. If the membrane and underlying substrate are installed properly, then shrinkage is less likely to occur. The installation method also matters. Adhered installations (which means the membrane is glued down to the substrate) are less likely to be punctured but they can be more prone to shrinkage since there is no slack to allow for normal expansion and weathering. A loose installation (which means the membrane is only attached at certain points) has more slack so it is less likely to suffer shrinkage.

3. Repair

There are some repair options if shrinkage does affect your roof. Shrinkage along the edges and around rooftop fixtures is the simplest to remedy. Old flashing and trim must be removed and a new strip of EPDM is installed over the exposed substrate. This new strip also overlaps the old EPDM membrane margin. Then, fresh flashing is installed over the repair to further anchor it down and prevent leaks. If there is shrinkage in the center of the roofing (perhaps due to a tear or puncture), then an EPDM patch will be installed over the area. Keep in mind that these patched areas will require ongoing inspections because they will be more prone to leak formation going forward.

Shrinkage can be a real problem on a commercial roof, but it doesn't have to be your problem. Contact commercial roofing services for more help with any roof shrinkage concerns you may have.


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