Have you have ever noticed waviness, wrinkles, or a buckled appearance on flat metal panels, such as metal wall panels and roofing? That’s oil canning. This type of stress buckling can happen on just about any type of flat sheet metal including aluminum, steel, and copper. Oil canning is usually noticeable prior to construction, and can appear more prominent when sunlight or other lighting reflects off the irregular metal surface.
What causes oil canning?
Oil canning’s wavy appearance is caused by stress on the metal and inherent to the metal. Metal stress can happen at any time during the milling process when the metal is rolled from its coil form, and while slitting and forming during panel fabrication. Additional stresses can occur during assembly at the fastening points as sheet metal is formed into wall or roof panels; if the structure is moved or sheet metal panels conform due to settling; due to intentional camber or bowing; or if improperly installed. Thermal expansion during the rolling process or from direct sunlight can also cause oil canning.
Can oil canning be prevented?
While it’s usually more of an aesthetic concern than a structural one, prevention is still better than the cure when it comes to oil canning.Careful consideration should be given to choice of metal, production, and project type in order to minimize unsightly oil canning. Coil fabricators and sheet metal manufacturers try to minimize oil canning during metal fabrication. During tension leveling, if metal is stretched beyond it’s yield point it creates a flatter surface less prone to oil canning. Panel design and finish should also be taken into consideration when trying to minimize oil canning. For example, visible oil canning may be less noticeable on lighter colored exterior metal panels. Using fasteners that allow for expansion, using backer rods and shimming materials, or using ribbed panels can also help relieve stress on assembled exterior panels, as well as minimize visible oil canning.