What is Oil Canning of a Metal Roof?

What is Oil Canning of a Metal Roof?

Anyone who invests in a metal roof expects to see the benefits they were promised. Long life, low maintenance, looks great, no color fade. These are just a few of the benefits buyers expect.

If the metal roof exhibits an effect commonly known as oil canning some building owners perceive that the value of the metal roof goes down. But should that really be the case? Let’s dig into the facts about oil canning.

What is oil canning?

Oil canning is something you see when a metal sheet appears wavy or distorted. Oil canning is an inherent characteristic of cold-rolled flat metal sheets. It only becomes an issue if the effect is highly visible to the naked eye as someone looks at a metal roof.

Oil canning may occur with any metal roofing substrate including steel, copper, zinc, and aluminum. It is most commonly an issue with concealed fixed roof systems. The color of the roof, roof finish, roof pitch, temperature, sunlight, season, and the angle the viewer is to the roof all play a part in the appearance of the oil canning effect.

Oil canning, if seen, does not indicate quality or structural issues with the roof. Instead, it is purely a visual appearance phenomenon.

What causes oil canning?

Determining the root cause of oil canning is difficult to definitively identify.

Possible causes include:

  • Deviations in the roof sub-structure
  • Twisting the panel excessively during installation
  • Over-driving fasteners
  • Movement of the underlying structure
  • Uneven stresses at the fastening points
  • Temperature variation along the roof (usually when one part is in direct sunlight and another in the shade)
  • Installing wider panel widths
  • Issues with the rolling process at the mill including poorly adjusted or worn roll formers
  • Distortions introduced during the slit or forming process

Considerations during product selection to minimize oil canning in a metal roof

Because it’s purely aesthetic, oil canning isn’t a concern in many building applications. But for high-slope or high-visibility projects where oil canning would be problematic, there are some steps that can be taken during the product selection phase to reduce the phenomena of oil canning.

It is possible to introduce oil canning during the sheeting manufacturing process. So it’s incredibly important to select a roll former with trained technicians who understand the importance of ensuring that equipment is properly maintained and calibrated before production begins.

The sheeting team on site must also be properly trained on the installation of the specific profile, and how to prevent oil canning.

In conclusion, if the metal sheeting is produced on site with oil canning, the sheeting team can try and install the metal sheeting in such manner to reduce the appearance of oil canning , but it cannot be eliminated entirely.