Oil canning is a wavy or distorted appearance often seen on copper roofs or metal siding, caused by uneven stress distribution in the metal panels. Copper’s natural softness and flexibility make it especially susceptible to oil canning when expansion and contraction occur due to temperature changes. This happens because the panels are either too tightly fastened, improperly installed without enough clearance, or attached to an uneven surface. While oil canning is mostly a cosmetic issue, it can be frustrating for homeowners who want a smooth, polished look. You can do a simple check by gently pressing on the curved or wavy areas; if the ripples slightly shift, it’s oil canning and not permanent damage. Look for exposed fasteners or panels that don’t lie flat, which can also signal installation problems. Also, check if your roof’s warranty covers oil canning, as some manufacturers treat it as a normal condition rather than a defect.
Fixing oil canning typically requires a professional approach to relieve stresses and improve panel alignment, often involving re-fastening or adding clips to allow for movement as the metal expands and contracts. Applying a slight amount of tension along the edges can help flatten some waves but must be done carefully to avoid further distortion or damage. When calling a roofer, ask if they have experience specifically with copper roofing and if their repairs will be covered under a warranty. It’s helpful to inquire about the methods they use to prevent future oil canning, such as proper fastening techniques or allowing for thermal movement. If you notice large or increasing waves, visible buckling, or leaking, it’s best to have a professional evaluate the roof, as these could indicate more serious installation or structural problems.