Oil-Canning: Specifying Wide Flat Panels in Metal Cladding

This post is intended to inform building designers, architects, specifiers and owners on the phenomenon called "oil-canning". Oil-canning is associated with all thin sheet metal products and occurs in the wide flat portions of the cladding profile. It is seen as a series of standing waves, or regular bumps and hollows alternating along the flat length of the profile. This waviness, when viewed under certain conditions, can be undesirable aesthetically and may not meet with the owner's expectations. The CSSBI wants to help avoid this situation.

The cladding manufacturers are well aware of the potential for oil-canning in their cladding profiles. It is important for the proper steps to be taken during manufacturing to produce a quality product; therefore, specifiers should insist on product from a reliable, experienced cladding manufacturer, like a CSSBI member company.

Quality control, however, cannot end on the shop floor. The building project needs the cooperation and knowledge of everyone involved to enhance the quality of the finished job. Oil-canning is a phenomenon that can be minimized if the following factors are considered.

Sheet Thickness: The thicker the sheet, the flatter the profile can be maintained.

Flat Width: The narrower the flat width of the cladding element, the harder it will be for that area to develop into the noticeable oil-canning waves.

Temperature: The expansion and contraction of the cladding sheet due to changes in temperature creates stresses which will exaggerate oil-canning. 

Cladding Orientation: Cladding profiles can be installed both vertically and horizontally to achieve

different architectural effects. The appearance of oil-canning in a vertical application is less pronounced than in a horizontal application due to the different way the eye of the observer perceives the standing waves.

Paint System: The nature of the paint system selected for the cladding is a strong contributor to controlling the visual impact of oil-canning. Textured finishes in lighter colours will reduce the visibility of oil-canning where the identical cladding in a darker colour with a smooth finish will highlight any irregularities.

Cladding Slope: The slope of the wall or roof on which the cladding is mounted will affect the visibility of oil-canning by changing the angle of incidence of the reflected light. 

Handling: Carrying of panels in the flat, or twisting of the panels during lifting, can induce a wavy appearance to a previously flat panel.

Installation: Over-engagement of the cladding panel and over-driving of fasteners are two installation related factors which can contribute to oil-canning. 

Erection Tolerances: Out-of-straightness of the structural supporting members will increase oil-canning by inducing bending stresses into the profile. 

To learn more about oil-canning and how to prevent it, download Fact Sheet 13: Position Paper on Oil-Canning: Specifying Wide Flat Panels in Metal Cladding