Oil canning of metal panel roof systems can be a controversial issue because an owner's or designer's aesthetic expectations often are not realized when confronted with the appearance of oil canning.
Some building owners believe a metal roof system never should oil can, but oil canning is an inherent characteristic of metal. You can attempt to reduce it or mask it, but it is virtually impossible to stop. A contractor who informs his customers about the potential for oil canning and provides options for minimizing it can reduce the chance of controversy. A contractor also must make it clear to customers that oil canning will not affect the performance of a metal panel roof system.
Oil canning occurs when there are uneven stresses within metal. Uneven internal stresses can develop when poor quality metal coils with side camber or nonstraight edges pass through a roll-forming machine. NRCA suggests tension leveling be specified and contractors specifically order tension-leveled metal.