Understanding Striations and Preventing Oil Canning in Metal Roofing

Striations can help prevent the visual appearance of oil canning. Photo courtesy of K&L Roofing, Inc.

Metal roofing has become a popular choice for both residential and commercial buildings due to its durability, energy efficiency, and modern aesthetic. However, one common issue that can arise with metal roofing is the appearance of oil canning. Understanding oil canning and knowing how to prevent it using striations (and other best practices) is crucial for ensuring a high-quality, visually appealing roof.

Striations add stiffness to the metal panels.

What Are Striations?

Striations refer to deliberate, shallow grooves or lines rolled into the surface of metal roofing panels. These lines can be either subtle or more pronounced, depending on the design. The primary purpose of striations is to enhance the structural integrity of the metal panels and improve their aesthetic appeal.

Striations help to:

1. Minimize Glare: By breaking up the surface of the metal, striations reduce the amount of light that reflects off the roof, thereby reducing glare.

2. Prevent Oil Canning: Striations add stiffness to the metal panels, helping to reduce the visible waviness known as oil canning.

Metal roof with oil canning from improper installation. Photo courtesy of Metal Roofing Alliance.

What Is Oil Canning?

Oil canning is a term used to describe the visible waviness or distortion that can appear on flat metal surfaces, such as roofing panels. This effect is often most noticeable in the broad, flat areas of the panels and can be caused by several factors, including:

1. Material Stress: Residual stresses from the metal manufacturing process can lead to oil canning.

2. Thermal Expansion: Temperature fluctuations can cause the metal to expand and contract, leading to waviness.

3. Improper Installation: Incorrect fastening techniques or inadequate support can exacerbate oil canning.

4. Panel Width: Wider panels are more prone to oil canning than narrower ones.

Preventing Oil Canning

While it is impossible to eliminate the risk of oil canning entirely, several strategies can significantly reduce its likelihood and severity:

True Metal Supply's DuraLock 100 metal roof panel with striations

1. Design Considerations:

• Striations: Incorporating striations into the design of metal roofing panels adds rigidity and reduces the flat surface area, helping to minimize oil canning. (See DuraLock 100 standing seam metal roof panel with striations.)
  

• Embossing or Stamping: Adding embossed or stamped patterns can also help to break up flat areas and reduce visible distortions. (See stamped Victorian Shingles below.)