What Causes Roof Shrinkage and How to Fix It

what causes roof shrinkage

Roof shrinkage is no easy matter to deal with. Roof shrinkage is the shrinking or shortening of the membrane, which coats your roofing materials. It is most common on EPDM or modified bitumen roofs and is usually caused by aging of the material, poor installation, or excessive UV exposure. Thanks to technological advancements and improvements to EPDM roofs, shrinkage has diminished significantly.

Roof shrinkage often results in the pulling of flashings at curbs, penetrations, and walls. This leads to splits and cracks that allow moisture in, which may result in leaks. Let’s dive into how to prevent it and fix it!

Why They Shrink

Many different factors can cause EPDM shrinkage. Most have something to do with substrate deterioration. Other factors include: poor quality materials, poor design, improper installation and poor workmanship. Modified bitumen sheets should not be set in ambient temperatures of 40 degrees or below. It doesn’t matter what adhesion application method you use. The issue is with the membrane sheets.

Prevention Is the Key

To prevent shrinkage, use high-quality EPDM membrane mixtures only. Even with the best workmanship, poor quality EPDM membrane will shrink. Always remember to invest in a good foundation or substrate.

Fixing Roof Shrinkage

To fix EPDM shrinkage, keep the following in mind: remove the entire flashing system, clean and prime the adjacent EPDM membrane material to make a durable tie-in, and then replace the flashing with EPDM membrane material, not neoprene. If the surface of the bitumen membrane is too weathered, apply asphalt primer and allow it to dry. Cut a patch of like material eight inches larger around the area for repair. Install the patch according to the manufacturer’s recommendation.