What Is Oil Canning On Metal Roof? (5 Causes And Best Solutions)

It’s a well-known fact that metal roofing systems can last for decades with regular maintenance and minimum care. However, oil canning on metal roof is one of the most prominent problems of metal roofs.

Oil canning on metal roofs is the occurrence of uneven patterns on metal panels, especially in the flat and broad areas of the metal roof.

It is caused by uneven decking, thermal expansion, poor handling and installation, color and gloss type, etc.

In this article, you will learn about oil canning on a metal roof, the various causes of it and all the possible solutions.

What is oil canning?

Oil canning on metal roof is defined as “a moderate deformation or buckling of sheet material, particularly common with flat sheet metal surfaces.”

In common terms, it’s the waviness or bumps of metal roofs, panels or metal sheets. It has no proven drawbacks. However, it strips your metal roof of its aesthetics.

Does Oil Canning happen on all types of metal roofs?

Oil canning happens to all types of roofs. i.e. copper, aluminum, zinc, and steel. Any roof having broad metal panels face the issue of oil canning. So its safe to say Oil canning happens of mostly all types of metal roofs.

What Causes Oil Canning On Metal Roofs?

There are several reasons for oil canning on metal roofs. Below are the seven most common ones that may lead to oil canning in your metal roof.

#1 Uneven Roof Decking.

Roof decking is the base on which the roofing system is laid. There is a roof decking below every metal roofing system. This decking is supported by structural roof steel beams, trusses, or open web joists. It spans between these roof beams, trusses, or open web joists to form a permanent base for the roofing system.

If this decking is uneven or tilted, the above roofing layers may be uneven or tilted too. Which will cause the metal roofing panels to bend or rearrange themselves causing oil canning.

#2 Improper Storage And Handling.

Metal sheets are used for roofing, construction, automobile or any other application. Must always be handled and stored with care both before and after roll-forming or slitting.

Like wooden panels, metal sheets/coils to are damaged by water. To prevent rust, it’s a must to store these sheets in a dry place. Away from a humid and moist environment.

However, unlike wood, metal panels are more susceptible to bending, curving and changing shape during, handling and moving. Constant movement, twisting and improper handling cause oil canning in metal roofs.

#3 Thermal Expansion.

Thermal expansion is common in every roofing system. The metal roof expands in heat and contracts in cold. While installation the thermal movement of the metal should be considered. Double pinning at the edges restricts the thermal movement, causing oil canning due to excessive stress.

Also, if the sun exposure is uneven along the roof. Meaning one side of the roof is subjected to the sun more than the other. Temperature varies along the roof, causing thermal expansion at different rates. This also results in oil canning.

Noisy metal roofs are also a by-product of thermal expansion.

#4 Poor Roof Installation.

A faulty installation is pretty much the root cause of every roofing problem. If the metal roofing system is not installed properly, a string of issues may occur. It may be caused by one or more of these roofing issues.

#5 Movement Of The Supporting Structure.

As mentioned above roofing systems are laid above a decking and supporting structure. If this supporting structure changes, moves or is no longer like its original self. It adds stress to the metal panels which causes oil canning.

As the metal roof panels were installed as per the original structure. Any change in it forces the metal roof sheets to flex and adjust as per the new structure, resulting in stress and turn oil canning.

Structures hardly change their original shape. If it does, it’s mostly due to extensive weathering or a natural calamity.

#6 Color And Gloss Type.

Color and gloss tend to slightly affect oil canning. Light shades are less prone to oil canning than darker shades. Moreover, a matt finish decreases the chances of oil canning compared to a glossy finish.

Ideally, to minimize oil canning in metal roofs select light-coloured low-glossy/matt metal panels.

#7 Misalignment Of The Panels.

Precision is the key when it comes to any roof installation process. Sometimes, due to inaccurate measurements, the metal roofing panels are misaligned.

Ideally, to rectify the misalignment, the entire panel should be redone. However, if this is not possible then the respective panels need to compensate for the misalignment.

This adds stress to the panels, leading to oil canning on metal roofs.

How To Minimize Oil Canning On Metal Roofs?

Now that we have understood the causes of oil canning. Let’s see the possible solutions to the problem.

1 Let Your Panels Be Narrow.

Oil canning is more visible in wide panels. Choosing panels with less width may solve the problem. Panels with a width of 18” or below are ideal to avoid oil canning.

2 Use Matt Finished Metals To Reduce Reflectivity.

As discussed above, extremely reflective surfaces are more inclined to oil canning. Hence choosing matt finished roofing panels, reduces the reflectivity of the sun reducing the chances of oil canning.

3 Purchase Tension-Levelled Metal.

Metal has memory. If it’s stretched or tensed, it tries to come back to its original form once the tension is relieved.

Metal sheets/coils used for roofing are often subjected to tension due to poor handling and constant movement. So once the sheet metal is fixed on your roof, it’s steady and free of any tension. Hence it tries to return to its former form. This results in oil canning.

To solve this problem, there are metal sheets that are tension-levelled. This means these metal sheets are stretched to such an extent that it’s unable to stretch any further. Neither is it able to go back to its original form.

Such sheets do not cause oil canning as they do not try to change their form.

4 Make Sure Your Roof And Deck Are Levelled & Consistent.

Roof decks are usually made up of plywood, metal or oriented strand board (OSB). Decks made of all of these materials could be uneven. It’s important to check the evenness of a deck before installing the above roofing layers.

If the decking of a metal roofing system is uneven/ curved, the metal roof panels will try to adjust themselves to mimic the shape of the decking. This, flexes the panels, causing oil canning in the process.

5 Buy Thicker Metal.

Metals are malleable. They adopt the shape of any object under the right amount of pressure. However, malleability increases with an increase in the thinness of the metal sheet.

To counter this, we can use thick roofing sheets, that do not easily give in under stress. This will help to reduce oil canning as thinner metals are more susceptible to oil canning compared to thicker metal sheets.

6 Make Use Of A Rib Roller.

If your metal roof panel isn’t narrow enough, then use a rib roller. Rib rollers are also known as stiffening ribs or striations. This is nothing but the pattern created on the flat portion of a metal sheet in between the seams.

The purpose of these patterns is to reduce the amount of flat surface on the metal panel. Although it’s not a foolproof solution. Nevertheless, if there is a less flat surface there are low chances of oil canning.

The patterns created by rib rollers are;

• Clip relief.
• Striated.
• Corrugated.
• Ribbed.

Does Oil Canning On Metal Roofs Go Away?

No, oil canning does not completely go away, unless you replace the metal panels. Little could be done to fix the issue once it occurs. But you can always prevent it by implementing the above practices.

However, the biggest preventive measure is to hire an experienced, knowledgeable and reliable roofer.

Conclusion.

Oil canning on a metal roof is one of the most common and mostly harmless issues of metal roofs. Minor oil canning sometimes fixes itself, as the seasons pass and the metal sheets settle over your roof. So, it’s not something to worry about. As it hardly compromises your roof.

I hope this article answers all your questions about oil canning. If you have any further questions feel free to comment down below.

Moreover, if you are experiencing oil canning connect with us anytime!

Leak-Stop is a one-stop destination to meet your roofing-related requirements. We offer roof repair, replacement, maintenance and inspection services all over GVRD (Greater Vancouver Regional District).

We offer a free inspection to first-time clients. Connect with us TODAY at 1 866 777 0084 for immediate assistance!