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Oil Canning in Metal Roofing

Presently, everyone desires to live in a beautiful and well-constructed house. There is a wide variety of designs that constructors use to build different houses. The roofing and the wall are essential parts of the house. For this reason, these parts ought to be well designed and maintained to keep the building attractive.

Constructors nowadays use metal pieces from steel, zinc, and copper to make walls and roofs. These metal roofs and metal wall systems are more resistant, impermeable, and durable. Metal roofing and wall systems are everywhere, from offices, hotels, schools, and homes. The majority prefer metal roofs and walls for various reasons, including their low maintenance cost, eco-friendliness, and warranty options.

However, since the roof and the walls are fully exposed, they get affected negatively by various elements, and from time to time. One of the most common occurrences that adversely affect these parts of a house is the Oil Canning.

Oil Canning in Metal Roofing

What is Oil Canning?


It is a visual occurrence that makes metal panels look wavy or distorted. This happens especially in portions where the metal roof or wall is wide and flat. Oil canning can appear on any kind of material, including copper, zinc, and aluminum (both galvanized and stainless). The appearance of the waviness varies depending on several factors, and there is no specific method of measuring this phenomenon. Such factors include;

· The time of the day

· The time of the year

· The angle from which you view the roof or metal wall

· The color and finish of the material.

Oil canning affects the surface of the metal roof or wall and not the structural properties of the panel system. Technically speaking, oil canning cannot make the roof or the wall to fail. For this reason, many companies don’t include this phenomenon in their warranty as a viable claim.


What are the Causes of Oil Canning?

There are quite a significant number of incidences that can lead to the development of oil canning, from manufacturing to handling and storage of the materials. In some situations, it is even harder to pinpoint the exact cause of this waviness in metal roofs and metal walls. However, the following are some of the most common reasons why oil-canning may occur:

· Stresses during the production process – Sometimes, there could be stresses during flattening and coiling processes. Three kinds of stresses occur during the production process that could lead to the occurrence of oil canning. They include:

· Full center – There is the creation of ripples along the center where the sheet is longer

· Wavy edge – This is when the sheet edge is longer along the side of the strip

· Camber – This is when the sheet or coil does not follow a straight line when laid flat

· Incorrect installation of the fastener – during the installation of the fasteners, oil canning could arise when;

· The fasteners are over-driven, causing stress on the lower part of the panel, especially where the panels are directly attached to the support system.

· Angling the fasteners. Installing the fasteners at an angle when joining the panel and the roof deck could also cause stress that leads to oil canning.

· Incorrect handling and storage – metal sheets used in construction require extra special care and support as constructors move them within the construction site. The sheets or panels should be carried in a way that they are parallel to the ground. It is recommended to support long sheets and panels at intervals of 10 to 12 feet. It is wise to handle these materials according to the manufacturer’s guidelines to reduce the chances of the sheets becoming wavy.

· Misaligned panels – in this situation, precise and accurate measurements are vital. Misaligning the panels could lead to stress on the metal as the installer tries to correct the misalignment. Most of the installers want to make work easier by adjusting the sheets without necessarily redoing the paneling. The stress experienced on the metal will undoubtedly cause oil canning.

· Color and finish – oil canning can occur on a metal roof and metal wall systems of any given color. Nevertheless, darker colors and high-gloss finishes show the oil canning effects more than lighter colors and low-gloss finishes.

· Restricted thermal movements – oil canning is likely to occur if the metal panel does not have adequate room for expansion and contraction during thermal movement. This is very common in cases where the panel is double pinned at the sides, inhibiting the centers from expanding and contracting freely. It puts stress on the metal panel, which consequently leads to the waviness of the metal roof or metal wall.

· Change in the structure of the construction – sometimes, a building may move due to racking, drift, or other causes. Oil canning may happen during this time as the metal panels are forced to conform to the movement of the building on which they are installed.

· Stresses inflicted during roll-forming and slitting – metals tend to try and revert to their original form by moving or warping. Oil canning can occur as the metal panels try to twist and move back to their original form.

· Differential solar exposure – this happens when some parts of the roof or wall are exposed to the sunlight while other parts are not. As the exposed side expands, the shaded one may not expand at all. This uneven expansion leads to uneven stress on the panel, hence, causing oil canning.

· Too many screws – some people assume that having a massive number of screws on their metal roofs or walls guarantees security. It might be valid to some extent. Nevertheless, using many screws hinders the flexibility that is needed by the material. This adds to the pressure inflicted on the metal as it expands and contracts, which finally leads to oil canning.

There are so many factors that could lead to oil canning. However, the most important thing is always to remember that any unnecessary movement, stress, and tension could increase the chances for the development of oil canning.


What to Consider Before and During Installation

Installers, contractors and the owners of the building should observe the following during the installation process of metal roof and wall systems:

· Storage – the sheets and coils should be kept dry, protected, and well supported in the storage facility. The materials should also be stored in a position that does not allow for twisting or stress.

· Panels – place one or two panels horizontally and support them well along the top side. Observe the flatness of the panels and look out for any oil canning signs. It’s also important to be very keen as the sheets go through the rolling and slitting equipment. The panels should be moved carefully both horizontally and vertically, to the site where they are required.

· Roof deck – place the panels on the roof deck and leave them loose and flat. Observe how flat the panels appear on the roof deck. Additionally, check for any convex or concave bowing or any other uneven part on the roof deck that could adversely affect the flatness of the metal panel.

· Installation – follow the manufacturer’s directives when installing clips and fasteners that join the panels to the substrate.

Following the above steps will help those involved to be able to notice oil canning on the panels before and during installation. If the oil canning appears too much at any given point, the installation process should stop, and the project owner consulted for further guidance.


Minimizing Oil Canning on Metal Roof and Metal Wall Systems


Several methods can be used to minimize the chances of oil canning metal roof and metal wall systems. Unfortunately, since metals tend to revert to their original form, these methods do not guarantee a 100% remedy for the oil canning. The best thing to do is to look out for any waviness on the metal panels before their installation. It will help minimize any extra costs after installation. The following are a few ways of reducing the occurrence of oil canning:

· Choose a thick and high-quality metal – Use a metal that is as thick as possible to reduce the chances for oil canning. Thick metals are stiffer, and this helps them resist deformation and creating waviness when exposed to unnecessary stress.

· Reduce the flat space on the panel using the rib rollers – the rib rollers are also known as striations. They are the indentations that are roll-formed into the flat portions of the panels between the seams. These indentations do not prevent oil canning, but they make it less apparent by reducing the amount of flat surface on the panels. Some of the most common rib rollers are ribbed, striated, corrugated, and clip relief. Additionally, it is also advisable to consider using panels with smaller widths, say 18 inches or less.

· Choose a light-color, low-gloss finish – darker colors emphasize any waviness that may appear on the panel. High-gloss (shinier) finishes increasing the reflectivity, making the oil canning more visible.

· Ensure the roof deck is even and well-leveled – one of the most common causes of oil canning is an uneven and unbalanced roof deck. If the metal panels are installed on a roof deck that bows or is not even, the metal will develop some stress as it tries to conform to this shape.

· Use tension-leveled metal – this is a coil that is stretched to a point where it cannot get back to its original state. Therefore, such a metal cannot create any waviness associated with stress wrinkling.

· Use baker rods – These are compressible foam strips that are fastened at the center of each panel during installation. The crown formed by these strips pushes any waviness from the center of the panel towards its edges. It makes oil canning less visible.

· Hire a knowledgeable and experienced roofing contractor – It is impossible to shutter the chances for oil canning ultimately. Nonetheless, having a qualified and experienced roofing contractor will reduce the possibility of making the situation worse. There are so many roofing contractors available in the market today. It would be wise to consider their reputation, experience, and credibility before settling for a specific one.

Repairing Oil Canning

There is no specific method of repairing or correcting oil canning once the panel is installed. Roofing contractors have to follow the right techniques to minimize the occurrence of this phenomenon. Nonetheless, if the waviness appears on only one or two panels, the homeowner could consider having them replaced. Appropriate measures should be taken during this replacement to ensure that the adjacent panels are not damaged.

If the problem is caused by the design of the materials used, a few adjustments could help reduce the severity of the waviness. Unfortunately, making such adjustments on already installed panels is not a walk in the park. It could even lead to extra costs incurred by the house owner in terms of labor. Generally, the best way to handle oil canning is trying to prevent it in the first place by proper design, handling, storage, and installation.

Metal roofing and metal wall systems are conventional nowadays. They are used in the construction of commercial buildings, residential houses, agricultural buildings, and architectural projects, among others. However, one of the most common challenges that come with constructing metal walls and roofs is the oil canning. It is a phenomenon that makes the roofs and walls to appear distorted or wavy. Though the effects of this phenomenon are not so severe, it messes up the beauty of the metal wall or roof.

As discussed above, several factors lead to oil canning. They include stress during production, improper handling, and storage of the materials, and misalignment of the metal panels. Proper processing, manufacture, storage, and installation is the best way to prevent or reduce the chances of oil canning on metal roofs and walls. Otherwise, there is no particular method of correcting the situation once the installation of the panel is complete.