Ribbed steel siding is a family of exposed-fastener metal panels defined by raised, evenly spaced ribs rolled into flat steel, sold mostly in 26 and 29 gauge and cut to length for walls and, in weather-detailed versions, roofs. The rib profile is what separates one panel from the next: trapezoidal box ribs (R-panel, PBR, 7.2 box rib) read modern and span farther, while rounded corrugated waves read agricultural. Most residential ribbed siding runs a nominal 36 inches wide with ribs on 9 to 12 inch centers.
Pages selling metal panels usually push one brand or blur “siding” and “roofing” into one bucket. The confusion costs money, because the same profile often serves both uses but the roof version needs a different side-lap detail to stay watertight. This guide puts the common ribbed profiles in one spec table, then shows where each belongs. It also covers pencil rib panels, a concealed-fastener wall product that is often shopped as ribbed siding but is built differently. For the fundamentals, start at our roofing basics hub.
What is ribbed steel siding?
Ribbed steel siding is cold-formed steel sheet with parallel ribs pressed in at set intervals, fastened to a wall or subframe with exposed screws through the flat between ribs or through the rib crown. The ribs add stiffness so a thin sheet resists bending, which lets a 29 or 26 gauge panel span open framing. The steel carries a metallic coating (galvanized zinc or Galvalume aluminum-zinc) plus a painted finish for color and corrosion resistance, the same base as galvanized and Galvalume steel roofing.
The category covers several distinct profiles. “Ribbed” in the trade usually means a panel with flat sections between raised trapezoidal or square ribs, as opposed to the continuous curves of corrugated. See how these fit the wider family in our guide to metal roofing types, panels, and profiles. Both are exposed-fastener systems, which sets them apart from concealed-fastener standing seam.
Ribbed steel siding profiles compared
The profile decides coverage width, rib depth, spanning strength, and look. Below are the ribbed and adjacent panels most siding suppliers stock. Rib heights and widths follow common industry roll-forming; exact figures vary by manufacturer, so confirm against the spec sheet before ordering trim.
| Profile | Rib height | Coverage width | Rib spacing | Common gauge | Best fit |
|---|---|---|---|---|---|
| Classic Rib / Tuff Rib / ProPanel | about 3/4 in | 36 in | about 9 in on center | 29, 26 | Homes, sheds, barns: siding and steeper roofs |
| R-Panel (R-Loc) | about 1 1/4 in | 36 in | 12 in on center | 26, 24 | Walls and siding, commercial and agricultural |
| PBR Panel | about 1 1/4 in plus purlin bearing leg | 36 in | 12 in on center | 26, 24 | Roofing: the watertight version of R-panel |
| 7.2 Box Rib | about 1 3/8 in | 36 in | 12 in on center | 26, 24, 22 | Walls and roofs needing longer clear spans |
| U-Panel | about 1/2 to 3/4 in | 36 in | 12 in on center | 26, 29 | Budget walls and utility roofs |
| Corrugated (7/8 in) | 7/8 in | 24 to 37.5 in net | 2.67 in pitch | 26, 29 | Agricultural and residential siding and roofs |
| 5V Crimp | about 1/2 in V | 24 in | V-ribs at panel edges and center | 26, 29 | Residential roofs, classic look |
The trapezoidal family (R-panel, PBR, 7.2 box rib) carries load across wider purlin spacing than a corrugated sheet of the same gauge, because a taller boxy rib resists bending better than a shallow wave. That is why steel building walls and low-slope panel roofs lean trapezoidal, while corrugated stays popular where the wavy look is the point. The 3/4 inch rib in the first row is sold by many mills as a combined roof and wall panel; our guide to Tuff-Rib panels compares sellers’ specs. Our master rib metal roof guide covers the MasterRib version.
Ribbed vs corrugated metal siding
The difference is the rib shape and how it changes coverage, waste, and look. Ribbed panels use flat runs between raised trapezoidal or box ribs and deliver a full 36 inches of coverage with no side-lap loss. Corrugated uses a continuous 7/8 inch rounded wave and gives 24 to 37.5 inches net after the required rib-over-rib side lap. Ribbed reads crisp and modern; corrugated reads classic and agricultural.
Corrugated carries a real waste penalty on coverage. The overlapping side lap eats roughly 10 to 12 percent of ordered material on a roof and about 6 percent on a wall, per Western States Metal Roofing. A trapezoidal panel ordered at 36 inches installs at 36 inches. On an equivalent job, that coverage math can make R-panel or PBR land 15 to 25 percent cheaper installed than corrugated even when the raw sheet price looks similar. Confirm both the panel price and the coverage waste before comparing quotes.
Pencil rib metal siding: a flush panel, not a ribbed sheet
Pencil rib metal siding is a flush or reveal wall panel with one or two small ribs rolled into its flat face, not an exposed-fastener ribbed sheet like R-panel. The panels are narrow and fasten through a concealed system; PAC-CLAD’s line, for example, runs 7 to 12 inches on center in 24 or 22 gauge steel or aluminum. The pencil ribs add strength to the flat, so PAC-CLAD recommends them on longer panels.
PAC-CLAD’s Reveal Wall Panel is a typical example. Its data sheet lists widths of 7, 11 or 12 inches on center at 1 inch high, in 24 or 22 gauge steel or .032 or .040 aluminum, with lengths from 4 to 25 feet. One pencil rib is offered on all three widths; two pencil ribs only on the 11 and 12 inch panels. On its flush and reveal wall panel page, PAC-CLAD says pencil ribs are recommended for longer panel lengths, and that flush panels go over a solid substrate with ice and water shield or, in limited applications, over framing.
Pencil ribs are one of several “pan conditions” a mill can roll into the flat. McElroy Metal recommends striations (a very minor bend every few inches) to reduce the appearance of oil canning, and notes that pencil ribs or planks are usually more noticeable after installation. Choose pencil ribs for the lined look; choose striations if you want the wall to read flat. Our guide to striated vs flat metal panels explains how each handles oil canning.
| Feature | Exposed-fastener ribbed panel (table above) | Pencil rib flush or reveal panel (PAC-CLAD example) |
|---|---|---|
| Fasteners | Exposed screws through the flat or rib | Concealed fastening system |
| Width | 36 in coverage (corrugated and 5V narrower) | 7, 11 or 12 in on center |
| Rib | Major ribs about 1/2 to 1 3/8 in tall | 1 in panel height; one or two small pencil ribs in the flat |
| Common gauge | 29, 26, 24 (22 on 7.2 box rib) | 24 or 22 steel; .032 or .040 aluminum |
| Backing | Spans open framing | Solid substrate, framing only in limited applications |
Can the same ribbed panel go on a roof and a wall?
Often yes, but the roof version needs a weathertight side-lap detail the wall version skips. R-panel and PBR share the same 36 inch, 1 1/4 inch trapezoidal profile. PBR adds a purlin bearing leg, a folded lip under the overlapping rib that seals the side lap and gives the fastener a solid bearing surface. That detail is why PBR is specified for roofs and plain R-panel is specified for walls and siding.
Use these rules when a supplier offers “R-panel” for a roof:
- For a wall or siding, standard R-panel is correct; the exposed fasteners and simple side lap are fine on a vertical surface.
- For a roof, ask for PBR (also sold as R-panel roofing) so the side lap has the purlin bearing leg and factory-applied or field-applied sealant.
- On any exposed-fastener roof, add inside and outside foam or metal closure strips at the eave and ridge and follow the maker’s screw pattern.
- Check the minimum slope: most exposed-fastener ribbed and corrugated panels are rated for roofs of 3:12 and steeper, with some approved to lower pitches only with sealed laps per the manufacturer.
If the roof is on a manufactured home, the panel is only part of the decision: a metal roof-over there also has to be checked against the home’s original design loads, which our mobile home roof replacement guide walks through.
What gauge to choose for ribbed steel siding
For residential ribbed steel siding, 26 gauge is the common structural choice and 29 gauge is the budget option; commercial and long-span walls step up to 24 or 22 gauge. Lower gauge numbers mean thicker steel: 29 gauge is about 0.0142 inch, 26 gauge about 0.0179 inch, 24 gauge about 0.0239 inch, and 22 gauge about 0.0299 inch for hot-dipped galvanized steel.
Our breakdown of 26 vs 29 gauge steel covers the tradeoff in detail. Thicker steel resists oil-canning (visible waviness in the flat areas), dents, and wind uplift, and it usually carries a longer paint warranty. On siding, 29 gauge holds up well on protected walls, while 26 gauge is the safer pick on tall or exposed elevations. For panels doing double duty as a roof, 26 gauge or heavier is the usual floor.
How much ribbed steel siding costs
Ribbed steel siding panel material runs roughly $1.00 to $3.50 per square foot depending on profile, gauge, and finish, with installed wall pricing commonly $4 to $9 per square foot including trim, fasteners, and labor. Corrugated tends to have the lowest sheet price; heavier trapezoidal box rib in 24 or 22 gauge sits at the top. Prices move with steel coil costs, so treat these as planning ranges, not quotes.
| Cost item | Corrugated (7/8 in) | R-panel / PBR | 7.2 box rib |
|---|---|---|---|
| Panel material, per sq ft | $1.00 to $2.50 | $1.20 to $3.00 | $1.50 to $3.50 |
| Installed on a wall, per sq ft | $4 to $8 | $4 to $8 | $5 to $9 |
| Coverage waste | 10 to 12% (roof), ~6% (wall) | Minimal, full 36 in | Minimal, full 36 in |
Trim drives a bigger share of the bill than buyers expect. Corners, base, J-channel, rake, and eave trim, plus screws and closures, can add 20 to 35 percent on top of the panel line. A tight quote lists panels, trim, fasteners, and closures separately so the coverage-waste math is visible. Steel remains one of the most-used residential roofing materials by share, as tracked in our roofing material market share report.
How to pick a ribbed steel siding profile
Match the profile to the surface, span, and look you want, in that order. The steps below sort the common choices without over-buying gauge or trim.
- Decide surface: wall or siding points to R-panel, Classic Rib, or corrugated; a panel roof points to PBR, 7.2 box rib, or a corrugated roof-rated sheet.
- Check the span: wide open framing favors a taller trapezoidal rib (7.2 box rib, R-panel) that carries load between fewer supports.
- Pick the look: crisp modern lines favor box ribs; a barn or farmhouse look favors corrugated or 5V.
- Set the gauge: 29 for protected walls, 26 as the all-round default, 24 or 22 for tall exposed walls or long spans.
- Confirm the finish and coating: Galvalume or galvanized base with a painted PVDF or SMP finish for color retention and warranty.
Ribbed steel siding FAQ
What is ribbed steel siding?
Ribbed steel siding is exposed-fastener metal wall paneling made from cold-formed steel with parallel raised ribs, usually trapezoidal, at set spacing. The ribs stiffen a thin 26 or 29 gauge sheet so it spans framing. Panels are typically 36 inches wide, carry a galvanized or Galvalume coating plus paint, and attach with screws driven through the flat or the rib.
What is the difference between ribbed and corrugated metal siding?
Ribbed panels have flat sections between raised trapezoidal or box ribs and give a full 36 inches of coverage with no side-lap loss and a modern look. Corrugated panels use a continuous rounded 7/8 inch wave, read more agricultural, and lose roughly 6 to 12 percent of coverage to the required side lap. Ribbed panels also span farther at the same gauge.
Can you use the same ribbed steel panel for siding and roofing?
Often the profile is shared, but the roof version differs. R-panel and PBR use the same 36 inch trapezoidal shape, yet PBR adds a purlin bearing leg that seals the side lap for watertight roofing. Use plain R-panel on walls and PBR on roofs, and add closure strips and sealed laps on any exposed-fastener roof.
What gauge is best for ribbed steel siding?
For homes, 26 gauge (about 0.0179 inch) is the common structural pick and 29 gauge (about 0.0142 inch) is the budget option. Tall or wind-exposed walls and long spans step up to 24 or 22 gauge. Thicker steel resists denting, oil-canning, and uplift and usually carries a longer finish warranty.
How much does ribbed steel siding cost?
Panel material commonly runs $1.00 to $3.50 per square foot by profile, gauge, and finish, and installed wall pricing is often $4 to $9 per square foot with trim and labor. Corrugated sheet is usually cheapest per foot, but its side-lap waste narrows the gap against full-coverage R-panel. Trim and fasteners can add 20 to 35 percent.
Is R-panel or PBR better for a roof?
PBR is the better roof panel. It shares R-panel’s 36 inch trapezoidal profile but adds a purlin bearing leg that seals the side lap and supports the fastener, which keeps a low-slope exposed-fastener roof watertight. Standard R-panel without that leg is meant for walls and siding, not roofs.
Reviewed by The Roofing Brief Team. Last reviewed: October 2026.