Corrugated metal is thin sheet metal, usually galvanized or Galvalume-coated steel, rolled into a repeating wave so it can span between supports without bending. The waves give a sheet a few hundredths of an inch thick enough stiffness to work as roofing or siding on barns, sheds, carports, metal buildings and, more and more, houses.
This guide explains how the wave works, the two profiles you will see most often, what gauge and coating to choose, how roof and wall coverage differ, and the installation details that decide whether a corrugated roof stays dry. Product figures come from manufacturer data sheets checked on October 30, 2026.
Why the Wave Shape Works
A flat sheet of 26 gauge steel sags under its own weight across a couple of feet. Bend the same sheet into waves and its depth goes from the sheet thickness to the full height of the corrugation. Stiffness rises with depth much faster than the extra steel used, the same principle that makes an I-beam deeper rather than thicker. The trade-off is that the panel is only stiff in one direction: across the corrugations it still flexes easily, which is why panels are always laid with the waves running from support to support across the purlins or girts.
Common Corrugated Metal Profiles
Corrugated profiles are named by rib height and rib spacing (pitch). Two families cover most US products: the deeper 7/8 inch profile and the shallower 1/2 inch profile. The figures below come from two manufacturers; other brands roll slightly different widths and pitches, so always order from one maker’s sheet.
| Spec | 7/8 in corrugated | 1/2 in corrugated |
|---|---|---|
| Rib height | 7/8 in | 1/2 in |
| Rib spacing (pitch) | 2.67 in | 2-5/8 in |
| Coverage | 34.67 in roof / 37 in wall (39 in overall) | 24 in listed dimension |
| Gauges | 26, 24, 22, 20 | 29 standard, 26 optional |
| Lengths | 1 ft to 52 ft | up to 50 ft standard, longer by request |
| Recommended minimum roof slope | 3:12 | not stated on the wall panel page |
| Source | Western States 7/8 in corrugated data sheet | Robertson corrugated wall panel |
7/8 inch corrugated
The deeper rib is stiffer, spans farther between purlins and sheds water better. It is the usual choice for roofs and for modern residential siding. The Western States sheet lists it in steel, aluminum, copper and A606-4 weathering steel, with bare, galvanized, Galvalume and painted finishes.
1/2 inch corrugated
The classic barn and shed profile. It is lighter and cheaper, often sold in thin 29 gauge, and Robertson lists it for residential, light commercial, agricultural and storage buildings, installed vertically or horizontally. Its shallow rib makes it better suited to walls and steep roofs than to low-slope roofing.
Gauge: How Thick Is Corrugated Metal?
Panel thickness is given in gauge, where a higher number means thinner steel. 29 gauge is the light agricultural grade, 26 gauge is the common residential roofing grade, and 24 down to 20 gauge are used where panels span farther, take foot traffic or need to resist impact. Our steel gauge thickness chart converts each gauge to inches and millimeters. Note that published gauge thickness for coated sheet includes the zinc or aluminum-zinc coating, so the bare steel is slightly thinner.
Gauge affects more than durability. A thicker panel can span farther between purlins and resists oil canning (visible waviness in flat areas) better. Manufacturers publish load-span tables by gauge; on a roof that must carry snow or wind uplift, the panel gauge, purlin spacing and fastener pattern have to come from those tables and the building’s design, checked by the engineer of record where one is required.
Coatings and Finishes
- Galvanized. Steel coated with zinc, which corrodes first and protects the steel underneath. See what galvanized steel is and how coating weight affects its life.
- Galvalume. An aluminum-zinc alloy coating that generally lasts longer than plain galvanizing in most atmospheres. Our Galvalume guide covers where it should not be used, such as in contact with wet concrete or animal waste.
- Painted. A Galvalume or galvanized base with a factory paint system on top, sold in many colors.
- Bare or weathering steel. Uncoated sheet meant to rust for the look. Western States notes its bare steel panel is not pre-rusted and rusts naturally once exposed. Weathering steel forms a tighter rust layer than ordinary steel, but runoff still stains concrete and siding below.
Roof Coverage vs Wall Coverage
The same 7/8 inch panel covers 37 inches on a wall but only 34.67 inches on a roof. Roofs use a wider side lap so water cannot be driven sideways into the joint, and the data sheet calls for a bead of mastic in the overlap when the panel is used as roofing. When you estimate panels, use the coverage width for the application, not the overall sheet width.
Example: a gable roof 30 feet long, measured along the eave, needs 360 / 34.67 = 10.4, so 11 panels per side using the roof coverage figure above. Add end laps if the panels cannot run full length from ridge to eave.
Installation Details That Matter
Support framing
Corrugated panels can go over open framing, such as wood or steel purlins on a roof and girts on a wall, or over solid sheathing. Purlin spacing must stay within the manufacturer’s span table for the gauge and the design loads.
Fasteners
Corrugated is an exposed-fastener system: screws with sealing washers go through the panel into the framing. Use the screw type, length and pattern the manufacturer specifies, drive them square, and stop when the washer is snug but not crushed. Match the fastener material to the panel. On bare steel panels Western States recommends galvanized or stainless steel screws.
Slope
Exposed-fastener panels rely on gravity to move water past every lap and screw. The Western States sheet recommends a minimum roof slope of 3:12 for its 7/8 inch panel. Below the manufacturer’s minimum, choose a panel rated for low slope instead.
Cutting
Cut coated panels with snips, a nibbler or a metal-cutting circular saw blade designed for thin sheet. Abrasive cut-off wheels throw hot particles that embed in the coating and rust. Sweep metal shavings off the roof the same day for the same reason.
Where Corrugated Metal Is Used
- Roofing and siding on barns, sheds, workshops and carports
- Cladding on pole barns and steel buildings (see pole barn vs metal building)
- Residential siding and accent walls
- Wainscot panels on the lower part of a wall
- Fences, garden beds and privacy screens
- Interior ceilings and wall finishes
Corrugated Metal FAQ
What gauge corrugated metal should I use for a roof?
26 gauge is a common residential roofing choice; 29 gauge is usually limited to sheds and agricultural buildings. Heavier 24 to 20 gauge is used where panels span farther or carry higher snow and wind loads. The manufacturer’s load-span table for your purlin spacing decides the minimum.
Is corrugated metal the same as R-panel?
No. Corrugated has rounded, evenly repeating waves. R-panel and PBR panels have trapezoidal ribs spaced farther apart with flat areas between them. Both are exposed-fastener panels, but they do not overlap with each other.
Can corrugated metal go over shingles?
Some manufacturers and local codes allow it over one layer of shingles with furring strips or underlayment, others do not. Check the panel manufacturer’s instructions and your building department before planning on it.
How long does corrugated metal last?
It depends mainly on the coating, the climate and exposure to salt or chemicals. Coated and painted panels carry manufacturer warranties that state their expected performance; bare steel panels are typically sold without one.
Can I walk on a corrugated metal roof?
Step only on the panel directly over a purlin or other support, in soft-soled shoes. Stepping between supports can dent thin panels and break the seal at laps. Use proper fall protection on any roof.
Reference information only, not engineering advice. Disclaimer.