If you’ve ever looked at a metal roof or wall under the sun and thought, “Did they do that on purpose?”, chances are what you saw was oil canning — subtle waviness in what should be a flat surface. It’s not a defect, but a natural response of metal to stress, light, and installation. The key is minimizing it.
Let’s dig into why steel gauge plays a role, what causes oil canning (beyond just thickness), and what you should watch out for when picking materials.
What Is Oil Canning?
“Oil canning” is the visible waviness or rippling in the flat areas of metal roofing and wall panels. In engineering terms, it’s called elastic buckling or stress wrinkling. Metal Construction Association
It can happen in any metal panel system — steel, aluminum, copper — under the right (or wrong) conditions. Metal Construction Association
Because oil canning is a response to stress and movement, no manufacturer or installer can 100% guarantee it never happens. Metal Construction Association But with the right material choices, design, and installation, its effects can be greatly minimized.
How Gauge (Steel Thickness) Plays In
Steel gauge matters because thicker steel is stiffer and less able to deform under stress. That means less tendency for those ripples to form.
Because thicker gauges resist bending and flexing more, they help keep panel surfaces flatter under varying temperature and mounting stresses.
Beyond Gauge: What Really Drives Oil Canning
Thickness is just one piece of the puzzle. The MCA article outlines several uncontrollable and controllable factors that influence oil canning. Here are the big ones:
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Material selection & production process
How the steel is rolled, leveled, and processed can induce internal stresses that predispose panels to oil canning later. Metal Construction Association -
Panel design & cross-sectional shape
Some profiles inherently resist or hide waviness better than flat ones, especially if they include stiffening ribs, striations, or corrugations. -
Installation method & substrate quality
Uneven support, misaligned fastening, thermal expansion not accounted for — these can all cause stress that leads to rippling. -
Lighting conditions
Certain lighting (low-angle, harsh sunlight) exaggerates visual perception of waviness, even when the surface is structurally solid. Metal Construction Association -
Thermal expansion & contraction cycles
As panels heat and cool, they expand and contract. If there’s no room for movement or if attachment points are too rigid, stress builds and can show up as waviness.
What Homeowners & Contractors Should Look For
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Choose a heavier gauge when possible
While 29-gauge may be fine for some applications, if your goal is smooth aesthetics and long-term stability, 26-gauge or thicker is safer. -
Work with suppliers who optimize production
Good mills and fabricators relieve internal stresses, level coils, and provide better material straightness before fabrication. -
Use smart profile design
Profiles with stiffening features or subtle ribs help the panel resist deformation. -
Install correctly
Ensure straight, level substrates and allow for thermal movement. Fasten with care, not force. -
Manage expectations
Even the best system can show minimal waviness under certain lighting. That doesn’t mean failure — it’s a visual artifact more than a flaw.
Why Indiana Metal’s Standards Matter
We don’t just sell steel — we engineer panels with appearance and performance in mind.
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Standard trims are at least 26-gauge (an upgrade over many competitors).
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We partner with mills that relieve internal stresses and level coils.
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Our profiles and panel options are chosen to balance strength and aesthetic flatness.
Your roof or wall should look crisp, clean, and intentional — not rippled by stress or poor choice. With the right materials and strategy, that’s exactly what we build toward.
Jena Jackson
Marketing & Communications
I specialize in designing pretty things and writing the words – I bring creativity, clarity & a serious appreciation for US-made steel.