Many commercial buildings feature flat membrane roofs. The membrane pieces are sealed together at the seams, using a variety of methods, to ensure that there are no leaks. Unfortunately, seams can fail. The following are a few of the most common causes of seam failure on a flat membrane roof.
1. Insulation Problems
On most commercial roofs, there is a layer of insulation underneath the roof membrane. If the insulation layer isn't properly anchored at installation, it can eventually shift and warp underneath the roofing membrane. Insulation may also become malformed due to a leak that isn't properly repaired. Regardless of the cause of the insulation damage, it will put stress on the seam that can eventually lead to seam failure.
2. Sun Damage
UV rays from the sun age roofing materials, causing them to become brittle and weak. The seams are not immune to UV damage. Not only does the material become brittle over time, but the adhesive may also begin to shrink away from the seam. As the adhesive fails, the seams begin to pull apart and water leaks in. If not addressed quickly, the membrane may fail completely.
3. Failed Adhesive
Seams can be sealed in a variety of ways, using either cold-set or heat-set adhesives. Cold-set adhesives include glues and tar products, while heat-set adhesives use a heat gun tool to fuse the seam layers to the membrane below. If the adhesives aren't properly set or if they don't cure as they should, the seams can fail. Your roofer should check and double-check each seam at the time of roof installation to ensure against seam failure.
4. Thermal Shock
Extreme temperature changes can cause the material in the seams to shrink and expand, which over time puts stress on the seams. An extreme shift in temperature can shock the material, causing the adhesive to crack and the seam to fail. Choosing a light-colored membrane reflects heat, which can help reduce the chances of thermal shock.
5. Roof Age
Older roofs are more likely to have recurring seam failure problems. Over time the membrane material will shrink, causing gaps to form along the seams. Regular maintenance should include inspection of the seams and resealing any that are starting to show shrinkage. Your roofer may recommend replacing the membrane if the shrinkage is excessive.
Contact a commercial roofing contractor in your area to learn more about roof seams.