Shrinking EPDM Roof Membranes: A Look At Common Causes And Prevention Mechanisms

Ethylene propylene diene monomer (EPDM) is a cost-efficient commercial roofing solution that has been gaining popularity in the roofing industry. With a life expectancy of over 50 years, EPDM roof membranes are sustainable. If you opt for EPDM roof membranes for your commercial property, roofing will be the least of your concerns. Although durable, EPDM roof membranes are susceptible to shrinking, which is an irreversible process. Shrinkages significantly affect the waterproofing ability of the membrane.

Common Causes of Shrinkage 

Depending on the type of EPDM membrane that was installed and how the membrane was installed, there are many different factors that can cause shrinkage. Most of the causes are related to substrate deterioration. Some of the most common causes include:

  • poor quality of materials. Depending on what type of materials and oils are used to make the EPDM membrane, there will be some fluctuations in terms of quality. If oil was not properly mixed in, the loss of oil will result in shrinkage and other molecular changes.
  • poor design. The design of the EPDM membrane must be capable of resisting some shrinking.
  • improper installation. Depending on the weather when the EPDM membrane was installed, the contractors will need to wait for the EPDM to either cool or warm up. Sheet expansion prior to attachment can cause what appears to be shrinkage when the EPDM membrane returns to its original size during cool weather. On the other hand, if the EPDM membrane was not properly relaxed prior to attachment, it will stiffen during cool weather.
  • inadequate workmanship. It is crucial to find an experienced roofing contractor because an inexperienced contractor may not provide the workmanship that is required for long-lasting results. In particular, you want to make sure that the base securement details are done well.
  • substrate deterioration. At times, the quality of the EPDM membrane is not the main cause of the shrinkage. If the substrate, where the base securement fasteners were installed, deteriorates, the fasteners can pull out, and cause the EPDM membrane to shrink.

Preventing Shrinkage

Knowing what causes the shrinking of EPDM roofing membranes can help you understand how to prevent the problem from happening in the first place. Shrinkages affect not only the waterproofing abilities of the membrane, but also the condition of the flashing. Ultimately, shrinking results in leaks, which cause water damage to the internal architectural structures of your home. To prevent shrinkage, consider:

  • purchasing high-quality EPDM membrane mixtures only. You want to make sure that the manufacturers have a good reputation on the market, and that there are very few complaints made about the product. Even with the best workmanship, shrinkages are unavoidable if the EPDM membrane is poor quality.
  • opting for assistance from experienced roofing contractors only. This is not a time to save money on labor. You definitely want to splurge a bit to make sure that you are getting the best workmanship possible. Keep in mind that an experienced roofing contractor will also have a keen eye for spotting any potential problems that may arise from the design of the membrane. 
  • invest in a good foundation, or substrate. Last but not least, make sure that you spend time reinforcing the substrate that will lie underneath the EPDM membrane. You want to make sure that the substrate is secure, and will not deteriorate for years to come, as this compromises the capabilities and durability of the membrane.


Invest the time and money to make sure that the EPDM membrane has been installed properly  by professionals, like those at John Criner Roofing Inc. A properly installed membrane will last for a long time, and will require very little maintenance and repairs over the years. Keep in mind that you will need the replace the entire membrane once it has shrunk. Replacement costs run high, and are very time-consuming.