Flat membrane roofing is a common option for many commercial structures, and PVC is a typical material used for many roof installations. While PVC has its fair share of advantages, there are also some drawbacks to understand. If your structure uses a PVC membrane flat roof, then shrinkage is one potential issue that may affect it over the long-term.
While roof shrinkage is often associated with PVC roofing, it can also occur on other membrane materials. Learning to spot this problem and understand how to address it can prevent damage to your building and save you from conducting additional repairs.
Roof Membrane Shrinkage Explained
Typical installation for a PVC roofing membrane involves securing the roof to the substrate with adhesive or physically nailing or screwing the membrane to the surface. In either case, the installers must then weld the joints and seams using a process known as hot-air welding. The membrane will overlap at the edges of the roof and wherever two sheets meet.
Since these membranes are long sheets of synthetic plastic polymer, they are vulnerable to shrinking over time and through weathering. In most cases, this shrinkage is not a severe problem, but it can potentially expose seams. Rarely, PVC membranes may cause structural damage to roofs with low parapet walls. When installed over the parapet, the membrane can shrink and physically pull the wall.
Recognizing the Signs of Shrinkage
Although shrinkage appears to be a material failure, it is often the result of installation issues. Recognizing shrinkage is relatively straightforward, however. When your roofing membrane begins to shrink, it may pull away at seams or come free from its adhesive. Even in cases where shrinkage is not severe, it will often be very apparent when inspecting the roof.
Anywhere that the membrane breaks, pulls away from a seam, or comes loose from flashing is an area where water can potentially infiltrate into the roofing substrate. Once moisture begins to make its way below the membrane, additional failures can occur as adhesive fails or the substrate itself rots. For this reason, it's essential to recognize the signs of trouble as early as possible.
Addressing the Problem
You won't always need to replace your roof just because the membrane has begun to shrink. Depending on the extent of the damage, it's usually possible for an experienced roofer to patch individual sections. If you suspect that your roof membrane is shrinking, it's best to have it evaluated by a professional as soon as possible.
For more information, contact a commercial roof repair service.