Reviewed by The Roofing Brief Team. Last reviewed: October 2026.
R-Panel dimensions are 36 inches of net coverage, 1-1/4-inch (1.25 in) trapezoidal ribs on 12-inch centers, and lengths cut to the inch up to about 45 to 50 feet, per the R-Panel data sheets from McElroy Metal, Nucor Building Systems and Best Buy Metals. R-Panel is an exposed-fastener steel roofing and siding panel sold under the generic name R-Panel and the original trade name Regent Rib, and McElroy describes it as one of the industry’s most widely used exposed-fastener panels. Metal Sales, Nucor and Western States Metal Roofing all roll a version. The detail that decides whether it belongs on a roof or only on a wall is the purlin bearing leg: McElroy requires the PBR leg on roof panels and not on wall panels.
What is R-Panel roofing?
R-Panel roofing is a through-fastened steel panel with wide, flat pans separated by tall trapezoidal ribs, screwed directly through the face of the metal into the roof deck or purlins. Each panel covers 36 inches, so three ribs land across every panel on 12-inch centers. It is the workhorse profile for agricultural buildings, pole barns, workshops, warehouses, and budget-conscious homes, and it installs faster and cheaper than a concealed-fastener system.
The name goes back to the Regent Rib profile, which the industry shortened to R-Panel. Because the geometry is not patented, dozens of mills roll a nearly identical panel, which is why pricing is competitive and material is easy to source regionally. R-Panel sits in the same family as corrugated roof panels and U-Panel, all of which are exposed-fastener profiles that lap rib over rib.
R-Panel dimensions and profile specs
The core R-Panel measurements are 36 inches of net coverage and a 1.25-inch rib height, formed from a coil width of roughly 40 to 48 inches before rollforming. Panels are cut to the inch on demand, commonly from 3 feet up to about 45 feet, and up to roughly 50 feet from some mills, which lets a single panel run eave to ridge on most roofs. McElroy lists the minimum slope as 3:12 without sealant and 1:12 with sealant, which is stricter than the 2021 IRC section R905.10.2 floor of 1/2:12 for lapped, nonsoldered-seam metal roofs with applied lap sealant (3:12 without). Follow whichever limit is higher.
| Spec | R-Panel figure |
|---|---|
| Net coverage width | 36 in |
| Rib height | 1.25 in |
| Rib spacing | 12 in on center (3 ribs per panel) |
| Coil width (pre-form) | 40 to 48 in |
| Panel length | Cut to the inch, about 3 ft to 45 ft (up to ~50 ft at some mills) |
| Minimum roof slope | 3:12 typical (down to 1:12 with sealant tape on some systems) |
| Fastener type | Exposed, gasketed screws through the flat |
| Panel weight (26 ga / 24 ga) | About 0.85 / 1.08 lb per sq ft |
R-Panel spec sheets compared, maker by maker
The four data sheets below agree on the core geometry (1-1/4 in ribs, 12 in rib spacing, 36 in coverage) and differ on gauge thickness, weight, maximum length and listed ratings. Weights differ because each maker publishes its own base-metal thickness and coating.
| Maker and sheet | Gauges and thickness | Weight (lb per sq ft) | Length | Minimum slope | Listed ratings | Source |
|---|---|---|---|---|---|---|
| McElroy Metal R-Panel | 26 ga standard; 24 and 22 ga optional (minimum quantity) | Not listed | Up to 50 ft, varies by plant | 1:12 with sealant; 3:12 without | UL 263 Class A, UL 580 Class 90, UL 2218 Class 4, Florida Product Approval, Miami-Dade, TDI | McElroy R-Panel product page, checked Oct 2026 |
| Nucor Building Systems R-Panel | 26 ga (0.0177 in), 24 ga (0.0222 in), 80 ksi yield | 0.86 (26 ga), 1.08 (24 ga) | Not stated | Not stated | ASTM E108 Class A, FM 4471 Class 1, UL 580 Class 90, Florida, Miami-Dade | Nucor R-Panel sheet dated 02/26 |
| Best Buy Metals R-Panel/PBR-Panel | 26 and 24 ga standard, 22 ga optional | 0.80 (26), 1.05 (24), 1.38 (22) | 5 ft minimum, 45 ft maximum recommended | Not stated | UL 2218 Class 4, UL 790 Class A, UL 580 Class 90, ICC-ES ESR-2385, Texas windstorm, Miami-Dade NOA | Best Buy Metals R-Panel tech sheet |
| Western States Metal Roofing PBR (Purlin Bearing R Panel) | 22, 24, 26 ga | Not listed | Cut to length | Not stated | Galvalume AZ55 option | Western States R Panel product page |
R panel coverage width matters for ordering. To sheet a roof, divide the total roof width by 3 feet to get the panel count, then add panels for overlaps and waste. The Roofing Brief metal roofing calculator handles the coverage math and the trim list so you order the right quantity the first time. For a lower-rib panel on the same 36 inch coverage, compare the 3/4 inch MasterRib profile. For how the same 3/4 inch rib sold as Tuff-Rib stacks up, see Tuff-Rib vs R-panel. Metal Sales sells its version as the Classic Rib metal roofing panel.
How wide is an R-Panel, and how many do you need?
An R-Panel is 36 inches, or 3 feet, of net coverage per sheet, and the overall rolled sheet is a couple of inches wider so the edge ribs can lap the next panel. You size a roof by the 36-inch net coverage, not the wider overall dimension: divide each roof plane’s width in feet by 3 and round up. The steps below turn that into an order quantity.
- Measure each roof plane: the along-the-eave width and the eave-to-ridge slope length.
- Divide the plane width in feet by 3 (the net coverage) and round up. A 40-foot-wide plane needs 14 panels, since 40 divided by 3 is 13.3.
- Set panel length to the slope length plus your eave overhang, ordering one length up to about 45 to 50 feet to avoid endlaps.
- Multiply panels per plane by the number of planes, then add roughly 5 to 10 percent for cutting waste and any coverage lost at sidelaps.
That count is a Roofing Brief calculation built only from the panel’s 36-inch net coverage and simple arithmetic, so confirm ridge, hip, and valley trim separately before you place the order.
What gauge is R-Panel?
R-Panel is stocked in 29, 26, 24, and 22 gauge, and lower gauge numbers mean thicker steel: Nucor’s sheet lists 26 gauge at 0.0177 in and 24 gauge at 0.0222 in. 26 gauge is the most common choice for roofing because it balances stiffness and cost, while 29 gauge is a light-duty option for sheds and short spans and 22 gauge is reserved for heavy structural runs. Pick the gauge from the purlin spacing and design load using the span table below, not from price alone.
| Gauge | Relative thickness | Typical use |
|---|---|---|
| 29 ga | Thinnest | Sheds, carports, short-span outbuildings |
| 26 ga | Standard | Most residential and light commercial roofs |
| 24 ga | Heavy | Wider spans, higher wind and snow zones |
| 22 ga | Thickest | Structural and demanding industrial runs |
Thicker steel carries more load per span: on Nucor’s 02/26 sheet, 24 gauge carries 90 psf gravity load at a 4 ft span against 59 psf for 26 gauge, and it weighs 1.08 vs 0.86 lb per sq ft. For a fuller breakdown of how gauge and coating drive per-sheet pricing across profiles, see the guide to roofing sheet metal gauge and price. The metallic coating matters as much as the gauge, and our comparison of galvanized vs Galvalume steel roofs covers how the two hold up.
How far can 26 and 24 gauge R-Panel span?
Nucor Building Systems publishes allowable loads for its R-Panel on three equal spans, with deflection limited to span/60. Read across from your purlin or girt spacing to the snow, live or wind uplift load your building official requires.
| Span between supports | 26 ga gravity (psf) | 26 ga uplift (psf) | 24 ga gravity (psf) | 24 ga uplift (psf) | Source |
|---|---|---|---|---|---|
| 2.0 ft | 118 | 109 | 180 | 113 | Nucor R-Panel sheet, 02/26 |
| 3.0 ft | 79 | 72 | 120 | 75 | Nucor R-Panel sheet, 02/26 |
| 4.0 ft | 59 | 54 | 90 | 56 | Nucor R-Panel sheet, 02/26 |
| 5.0 ft | 47 | 43 | 70 | 45 | Nucor R-Panel sheet, 02/26 |
| 5.5 ft | 43 | 37 | 58 | 41 | Nucor R-Panel sheet, 02/26 |
Best Buy Metals’ tech sheet uses a stricter L/180 deflection limit, so its numbers are lower: 26 gauge at a 4 ft span is rated for 73 psf inward and 60 psf outward, and at 5 ft it drops to 48 psf inward. Values are not interchangeable between makers; use the sheet for the panel you actually buy.
R-Panel vs PBR panel: the purlin bearing leg
The single detail that separates an R panel from a PBR panel is a small extended lip called the purlin bearing rib, or purlin bearing leg. PBR panel adds this leg under the major rib so the panel laps under the next panel and rests flat on the purlin, closing the void at the sidelap. Standard R-Panel laps major rib directly over major rib with no bearing leg, which leaves a small gap that can wick water on a low-slope roof. Both panels share the same 36-inch coverage and 1.25-inch rib, and Western States Metal Roofing puts the cost difference at 2% to 3%, which is why it says most manufacturers offer only PBR.
That gap is why McElroy’s R-Panel page states that roof panels require the PBR (purlin bearing return) leg while wall panels do not. Retail prices do not always follow the 2% to 3% rule: in October 2026 Woodson Lumber listed a 16 ft, 26 gauge Galvalume R-Panel at $67.95 and the matching PBR-Panel at $56.95. On a wall, water sheds off and the open sidelap never matters. On a roof, an ungasketed rib-over-rib overlap is a candidate leak point over time, especially below 3:12. If a supplier quotes “R-Panel” for a roof, confirm whether they are actually rolling the PBR version, because the two names are used loosely in the field.
| Feature | R-Panel | PBR panel |
|---|---|---|
| Coverage width | 36 in | 36 in |
| Rib height | 1.25 in | 1.25 in |
| Purlin bearing leg | No | Yes |
| Sidelap | Rib over rib, small void | Nested, closed lap |
| Best use | Walls and siding | Roofing and siding |
| Price difference | Baseline | About 2 to 3% more (Western States) |
R-Panel vs corrugated and U-Panel
R-Panel, corrugated, and U-Panel are all exposed-fastener profiles, but their rib shapes change stiffness and price. Corrugated uses a rounded 7/8-inch wave, U-Panel uses a squared 3/4-inch rib, and R-Panel uses a taller 1.25-inch trapezoidal rib that adds strength per gauge. In its AG Panel vs R Panel comparison, Western States gives the AG (U) Panel as 3/4 in ribs on 9 in centers with 36 in coverage, and puts the material saving of 29 gauge AG Panel over 26 gauge R-Panel at 10% to 15% with the same installation cost.
| Profile | Rib | Coverage | Relative cost |
|---|---|---|---|
| Corrugated | 7/8 in rounded | ~24 to 26 in | Lowest |
| U-Panel | 3/4 in squared | 36 in | Low |
| R-Panel / PBR | 1.25 in trapezoidal | 36 in | Low to mid |
| Standing seam | 1.5 to 2 in concealed | 12 to 18 in | Highest |
R-Panel puts its screws through the panel face at every support. Best Buy Metals specifies #10-14 XL wood screws into wood framing, #12-14 XL self-drilling screws into steel, and 1/4-14 x 7/8 in stitch screws at the side laps, each driven so it extends at least 1/2 in past the inside face of the support. If you want no exposed fasteners at all, choose a concealed-clip standing seam panel instead. See how the exposed-fastener family compares to concealed systems in the guide to screw-down metal roofing versus standing seam.
How much does R-Panel cost in 2026?
R-Panel material runs from about $1.15 per square foot for bare 26 gauge Galvalume to $5.00 or more for heavy, PVDF-painted panels in 2026, driven by gauge and paint system. Two October 2026 retail listings set the low end: McCoy’s Building Supply listed a 16 ft Metal Sales R profile panel in 26 gauge Galvalume at $54.99, and Woodson Lumber listed a 16 ft 26 gauge Galvalume R-panel at $67.95, about $1.15 and $1.42 per square foot of 36 inch coverage (Roofing Brief arithmetic). Silicone-modified polyester (SMP) paint sits at the low end, while premium PVDF (Kynar) finishes cost more and hold color longer; Western States Metal Roofing says it offers PVDF only in 24 gauge, which raises cost about 50% over 26 gauge SMP. Installed with labor, fasteners, closures, and trim, exposed-fastener metal runs about $6 to $10 per square foot in our 2026 roofing cost report, with roof complexity, tear-off and regional labor rates setting where a bid lands inside that range.
| Panel spec | Material per sq ft | Source |
|---|---|---|
| 26 ga, bare Galvalume (October 2026 listings) | $1.15 to $1.42 | McCoy’s and Woodson Lumber listings, Oct 2026 |
| 26 ga, SMP paint | $2.00 to $2.50 | Western States, What Is R Panel |
| 24 ga, SMP paint | $2.50 to $3.00 | Western States, What Is R Panel |
| 24 ga, PVDF paint | $2.50 to $3.50 | Western States, What Is R Panel |
| 22 ga, PVDF paint | $3.50 to $5.00 | Western States, What Is R Panel |
The material sticker is only part of an installed number. A realistic per-square (100 square feet) buildup adds gasketed screws, ridge and eave trim, closure strips, underlayment, and labor. At the 80-screws-per-square planning figure, a 30-square roof needs about 2,400 gasketed screws, and a hip roof needs ridge, hip and eave trim on every edge where a simple gable needs only ridge, rake and eave. Ask each bidder to itemize panels, screws, trim and closures so the bids compare line by line.
Worked example: R-Panel order for a 40 by 30 ft gable building
The table below sizes a simple gable roof with two 40 ft wide planes and a 16 ft panel run per side, using only the 36 in net coverage, the 80-screws-per-square planning figure and the Woodson Lumber 16 ft, 26 gauge Galvalume price from October 2026. Trim, closures and labor are excluded.
| Line | Calculation | Result | Source |
|---|---|---|---|
| Panels per plane | 40 ft / 3 ft = 13.3, round up | 14 | 36 in net coverage (maker sheets) |
| Panels, both planes | 14 x 2 | 28 panels at 16 ft | Roofing Brief arithmetic |
| Area covered | 28 x 3 ft x 16 ft | 1,344 sq ft (13.4 squares) | Roofing Brief arithmetic |
| Screws | 13.4 squares x 80 | About 1,075 | 80 per square planning figure |
| Panel material | 28 x $67.95 | $1,902.60 | Woodson Lumber listing, Oct 2026 |
Exposed fasteners: screw count, gaskets, and lifespan
R-Panel is screwed through the face of the metal with gasketed screws, and a common planning figure is roughly 80 screws per square (100 square feet) for a through-fastened panel, placed in the flat next to the ribs and along each purlin or the deck. Every one of those screws carries a rubber EPDM washer that seals the hole, and every washer is a wear part exposed to sun and heat.
EPDM washers age under sun and heat faster than the steel or the paint, and Best Buy Metals’ sheet warns that overdriven fasteners distort the panel, so washer compression is set at install. When washers crack or the screws back out from thermal cycling, the panel can leak at the fastener, and the usual fix is replacing those screws with oversized gasketed fasteners. Budget for that periodic service when you compare R-Panel against a concealed-fastener system that has no exposed penetrations.
- Plan about 80 gasketed screws per square, set in the flat pan, not on the rib.
- Drive each screw until the washer compresses flush, not crushed and not proud.
- Inspect washers every few years, especially on south and west exposures.
- Re-screw with larger-diameter gasketed fasteners once washers begin to crack.
When R-Panel is the right choice
R-Panel is the right pick when you want durable metal on a 3:12 or steeper roof at the lowest material cost and can accept exposed fasteners and periodic screw maintenance. It fits agricultural buildings, pole barns, workshops, garages, warehouses, and budget residential roofs. It is the wrong pick when you want a concealed-fastener look, a very low slope, or a roof you never want to service.
| If your project is | Choose | Threshold and source |
|---|---|---|
| A roof at 3:12 or steeper | PBR panel, 26 gauge minimum | McElroy: PBR leg required on roof panels; 3:12 without sealant |
| A roof from 1:12 up to 3:12 | PBR with tape sealant at every side and end lap | McElroy 1:12 with sealant; IRC R905.10.2 allows 1/2:12 with applied lap sealant |
| A roof below 1:12 | Standing seam, not R-Panel | Below McElroy’s 1:12; IRC R905.10.2 sets 1/4:12 for standing seam |
| Walls, wainscot or siding | R-Panel or PBR | McElroy: PBR leg not required on wall panels |
| Supports 5 ft apart with a design load over 47 psf gravity or 43 psf uplift | 24 gauge, or move supports closer | Nucor 02/26 table: 26 ga limits at 5 ft; 24 ga carries 70 psf gravity |
| A hail-prone area or an insurer asking for Class 4 | A panel listed to UL 2218 Class 4 | Listed by McElroy and Best Buy Metals; confirm on your maker’s sheet |
| Florida, Miami-Dade or Texas coastal permit | A panel with Florida Product Approval, Miami-Dade NOA or TDI listing | Listed on the McElroy, Nucor and Best Buy Metals sheets |
- Choose PBR over plain R-Panel for any roof so the purlin bearing leg closes the sidelap.
- Choose R-Panel for walls and siding where the open sidelap does not matter.
- Choose standing seam instead if you want concealed fasteners and minimal long-term maintenance.
- Step up to 24 gauge in high wind or heavy snow zones or on wider purlin spacing.
R-Panel and PBR are two 36 in, 1-1/4 in rib profiles in a field that also includes 3/4 in U-Panel and 7/8 in corrugated. Compare them against the full range in the guide to metal roofing panel types and profiles, and see how the profile fits larger buildings in the overview of commercial metal roofing systems. For a house rather than a barn, weigh it against the quieter, concealed-fastener options in the guide to residential metal roofing. For a low V-rib alternative, see our guide to 5V metal roofing.
Frequently asked questions
What is R-Panel roofing?
R-Panel roofing is a trapezoidal, exposed-fastener steel panel with 36 inches of net coverage and 1.25-inch ribs on 12-inch centers, screwed through the face into the deck or purlins. McElroy Metal calls it one of the industry’s most widely used exposed-fastener panels, used on barns, workshops, warehouses, and budget homes. It installs faster and costs less than a concealed-fastener standing seam system.
How wide is an R-Panel?
An R-Panel covers 36 inches, or 3 feet, of net roof width per sheet, with 1.25-inch trapezoidal ribs spaced 12 inches on center. The overall rolled sheet is slightly wider than 36 inches so the edge ribs can lap the next panel, but you size and order a roof by the 36-inch net coverage. Divide each roof plane’s width in feet by 3 and round up to get the panel count.
What is the difference between R-Panel and PBR panel?
PBR panel adds a purlin bearing leg under the major rib that nests under the next panel and closes the sidelap, while plain R-Panel laps rib over rib and leaves a small void. Both share 36-inch coverage and a 1.25-inch rib and cost within 2 to 3 percent of each other. PBR is specified for roofing, and R-Panel is often reserved for walls.
How much does R-Panel cost?
R-Panel material runs from about $1.15 to $1.42 per square foot for 26-gauge unpainted Galvalume at two October 2026 retail listings (McCoy’s and Woodson Lumber) to $5.00 or more for heavier, PVDF-painted panels. Installed with labor, fasteners, and trim, exposed-fastener metal runs about $6 to $10 per square foot in The Roofing Brief 2026 roofing cost report. Roof complexity, tear-off and regional labor rates decide where a bid lands in that range.
What gauge is R-Panel?
R-Panel is stocked in 29, 26, 24, and 22 gauge, where lower numbers mean thicker steel. 26 gauge is the standard for most roofs, 29 gauge suits sheds and short spans, and 24 or 22 gauge handles wider spans and higher wind or snow loads. Thicker gauge resists denting and oil-canning but adds cost per square.
How far can a 26 gauge R-Panel span?
On Nucor Building Systems’ 02/26 R-Panel sheet, 26 gauge carries 59 psf gravity and 54 psf uplift at a 4 ft span and 47 psf gravity and 43 psf uplift at 5 ft, on three equal spans with deflection limited to span/60. Best Buy Metals uses a stricter L/180 limit and lists 48 psf inward at 5 ft. Use the table for the panel you buy and the load your building official requires.
How thick is a 26 gauge R-Panel?
Nucor Building Systems lists 26 gauge R-Panel at 0.0177 in base-metal thickness and 0.86 lb per sq ft, and 24 gauge at 0.0222 in and 1.08 lb per sq ft. Best Buy Metals lists 0.80 and 1.05 lb per sq ft for its 26 and 24 gauge panels.
What is the minimum roof pitch for R-Panel?
McElroy Metal lists 3:12 without sealant and 1:12 with sealant tape at the side and end laps, and the 2021 IRC section R905.10.2 sets 3:12 without lap sealant and 1/2:12 with it for lapped metal roofs. Below the recommended slope, water drains slowly and the exposed rib-over-rib overlap on plain R-Panel becomes a leak risk. PBR panel and taped seams extend the usable low-slope range.
Can R-Panel be used for roofing?
R-Panel can be used for roofing, but the PBR version with the purlin bearing leg is the better roof choice because it closes the sidelap void that plain R-Panel leaves. McElroy Metal states that roof panels require the PBR (purlin bearing return) leg and wall panels do not. On any roof, confirm the panel has the bearing leg before you buy.
How long do R-Panel roofs last?
On an R-Panel roof the steel and paint usually outlast the exposed gasketed fasteners, which are the limiting part. EPDM washers age under UV and thermal cycling, so plan for periodic inspection and replacement of cracked or loose screws with larger gasketed fasteners. Coating sets the steel’s life: Best Buy Metals specifies AZ55 Galvalume per ASTM A792 for unpainted panels and AZ50 under paint. A concealed-fastener system avoids that service but costs more upfront.