Roof shrinkage is a common problem among “rubber” roofing systems, such as EPDM and modified bitumen. Here’s an in-depth look at the causes of roof shrinkage and what can be done to fix it.
Causes of Roof Shrinkage
When the outer roofing material shrinks, the roofing substrate becomes exposed to the elements, leaving it open to moisture intrusion that leads to problems like rot and roof leaks. Ethylene propylene diene monomer (EPDM) and modified bitumen, commonly referred to as “rubber roofs,” significantly expand and contract from outdoor temperature differences.
As the rubber roof ages, it becomes less elastic. At this point, shrinkage may result in fasteners and flashing getting pulled out. The outer roofing material may also get torn in the process.
Proper Installation Is Important
Most of today’s roofing manufacturers factor thermal expansion and contraction in their installation specifications. Roofers who heed such specifications in mind are unlikely to commit installation mistakes, such as installing substrate too close together or not having enough overlap between rolls.
Installation type can also be a factor. EPDM and other types of single-ply roofing can be installed either adhered to the substrate or loose-laid. The latter allows more slack for thermal expansion, but can be easily punctured by edged surfaces.
Repairing Roof Shrinkage
Fortunately, shrunken flat roofs can be repaired. The amount of work will, of course, depend on the extent of the damage. Torn parts in the middle can be repaired using patches and adhesive. Note that your roofing warranty may be able to cover the repair costs depending on certain conditions.
For example, since shrinkage occurs on relatively old roofs, the roof may be close to the end of its warranty period. If the damage caused by the shrinkage is due to improper installation, check if the roofing installer’s workmanship warranty will cover it.
Kidd-Luukko Corporation is your leading provider of roof replacement and repair services. Give us a call at (508) 799-9500, or fill out our contact form. We serve customers in Hartford, CT, Springfield, MA, and Providence, RI.