Metal panels are a durable, long-lasting material perfect for roofing and wall applications. However, one issue that often arises with flat metal panels is oil canning. This issue only affects the panel’s aesthetic, and is not a cause for rejection or failure of a roofing or wall application.
Oil Canning Defined
Oil canning is a visible, wavy distortion that affects cold-rolled metal products. It’s seen in the flat areas of metal panels, and can be characterized as a moderate aesthetic issue. Typically, the rippling, waviness, or buckling is especially seen in the broad area of a metal roof or wall. It can occur on all types of metal, including copper, aluminum, zinc, and steel.
To some degree, oil canning is inherent on all metal surfaces. Since metal has a highlight reflective surface, different conditions like the paint or finish you choose and changing lighting conditions can affect how visible the distortions are. Sometimes, even the angle at which you're looking at your roof or the way the sunlight is hitting it can change how visible the oil canning is or not. It’s important to know that oil canning is purely an aesthetic issue, and the Nation Roofing Contractors Association doesn’t consider it to be a cause for rejection or a failure in a roofing or wall system.
Causes of Oil Canning
The causes of oil canning can vary. Here are a few reason why your metal roof may be experiencing oil canning:
- Stress During Production/Milling Process — When a metal panel is produced, rollers are used in order to form the coils and sheets. Due to the small gaps within the rollers, there can sometimes be uneven or improper distribution of stress.
- Uneven Roof Decking — An uneven substrate or roof decking can also lead to oil canning. This can lead to slight contours, which eventually can lead to more visible distortion.
- Improper Installation — During installation, fasteners can be overdriven, driven in at the wrong angle, or even the wrong clip systems can be used. The panels themselves can also be misaligned. Improperly installing the metal panels can lead to uneven stresses. Make sure you’re hiring a contractor that’s worked with metal panels (specifically flat panels) before installation day to avoid any poor installation that could result in oil canning.
- Thermal Expansion & Contraction — If your metal panels are improperly installed, it can cause oil canning as the metal panels will have limited room to expand and contract with fluctuating temperatures. This can also occur if there’s different solar heating, meaning parts of the roof are if direct sunlight constantly and other parts are shaded. This uneven stress can lead to thermal expansion.
- Improper Handling or Storing — Before installation, it’s critical to ensure your materials are handled and stored with care. Metal panels should always be carried perpendicular to the ground so they do not bow. You should always follow the handling and storing instructions.
How to Minimize Oil Canning
Before you install your metal panels, there are few things you can do in order to minimize oil canning. You can take the following steps:
- Add Striations — Striations are a series of ridges, ribs, or waves added to metal panels in order to reduce or minimize the look of oil canning. They can help keep Standing Seam and other flat panels looking their best. You should talk to a Product Specialist about striated panel options.
- Choose a Thicker Gauge — If possible, when you’re selecting the details of your panels, choose to go with a thicker gauge that is more rigid (gauge refers to a metal panel’s thickness). By selecting a thicker metal, it makes it a bit harder for the metal to move and give in.
- Hire Expert Installers — Oil canning is a common result of faulty or poor installation. Ensuring you hire a team of installers who are experts with metal roofing can reduce the chance of oil canning occurring. They should make sure they’re installing the panels on a flat, even substrate or roof deck. They should also make sure to handle the panels with proper care and install them with the correct techniques.
- Choose Low Gloss Finishes or Textured Finishes — When choosing what finish you’ll use on your metal, choosing low-gloss or matte finishes can reduce metal's reflectively, making oil canning less visible. You can also go with textured finishes, which are matte, and will also help minimize the looks of waviness.
- Utilize Backer Rods (When Possible) — Installing backer rods on panels where they’re available can help minimize oil canning as well. These may be applied under flat panel applications depending on availability. Talk to a Product Specialist about this option.
- Choose More Narrow Widths — Since oil canning is more visible in the broad, flat parts of panels, choosing more narrow widths can reduce the look of this issue. With less space between panels widths, there will be minimized oil canning.
It’s important to understand that there is no 100% guarantee that your panels will not experience oil canning. There is no way to completely fix this issue after it has occurred. However, it’s equally as important to understand that this issue is completely aesthetic-related. If your metal panels experience oil canning, it does not mean the integrity or structure of your metal roof or wall system is compromised. Oil canning also does not affect a panel’s weather-tightness or water-proofing qualities. The best way to prevent it is to follow the suggested tips listed above BEFORE installation.
Got questions about your metal panels and oil canning? Get in touch with our team of Product Specialists.