Have you ever seen a metal panel that looked like it was wrinkled?
If yes, this is a term called oil canning. This can happen with metal products with a broad, flat area. Oil canning can cause wrinkles or waves in the flat area of metal roofing and siding panels. There are a few ways to help decrease oil canning such as adding striations, choosing a thicker gauge, hiring experts to install, choosing low glass finishes or textured finishes, when possible using backer rods, and considering a narrow width.