Corrugated Metal Roofing vs. R-Panel: Which Exposed Fastener System Is Right for You?
Not every project needs standing seam. For barns, workshops, outbuildings, agricultural structures, and some budget-conscious residential projects, exposed fastener metal roofing delivers solid performance at lower cost.
The two most common exposed fastener options are corrugated metal and R-panel. Both work well for the right applications, but they’re not interchangeable. Here’s how to choose between them.
Understanding Exposed Fastener Systems
Before comparing these two styles, let’s clarify what “exposed fastener” means.
Both corrugated and R-panel roofing attach with screws that penetrate through the panel surface into the roof deck or purlins below. The screw heads remain visible on the finished roof, seated on rubber or neoprene washers that seal the penetration.
This differs from standing seam, where fasteners are concealed beneath raised seams and never penetrate the weather surface.
The Trade-off
Exposed fasteners mean:
- Lower material and installation cost
- Simpler, faster installation
- Fastener maintenance required over time (washer deterioration, re-tightening)
- Shorter lifespan than concealed fastener systems (25-40 years vs. 50-70 years)
For many applications, this trade-off makes sense.
Corrugated Metal Roofing
Profile and Appearance
Corrugated metal features a wavy, sinusoidal profile with rounded ridges and valleys. It’s the classic “barn roof” look that’s been used for over a century.
Standard corrugated panels have:
- 2.67-inch repeating wave pattern
- 1/2-inch to 3/4-inch depth
- 26-inch or 36-inch panel width typically
The look is utilitarian and agricultural. It says “working building” or “rural property.”
Strength Characteristics
The curved corrugations provide strength through geometry. However, corrugated metal is generally:
- Moderate strength across the width
- Lower resistance to foot traffic (panels can oil-can or dent)
- Adequate for typical residential and agricultural loads
- Less rigid than trapezoidal profiles
Common Applications
Corrugated metal works well for:
- Barns and agricultural buildings
- Storage sheds and outbuildings
- Carports and equipment covers
- Rustic or farmhouse-style homes
- Budget residential projects where the aesthetic fits
- Pole barns and simple structures
Material Options
Corrugated roofing typically comes in:
- Galvanized steel: Zinc-coated steel, natural silver finish, most economical
- Galvalume steel: Aluminum-zinc alloy coating, better corrosion resistance
- Painted steel: Various colors available
- Aluminum: Lighter weight, better corrosion resistance, higher cost
Gauges typically range from 29-gauge (lightest, most economical) to 24-gauge (heavier, stronger).
R-Panel Roofing
Profile and Appearance
R-panel (also called PBR panel or AG panel) features a trapezoidal rib profile with flat pans between raised ribs. The ribs stand taller than corrugated waves, typically 1.25 inches high.
Standard R-panel dimensions:
- 36-inch panel width typical
- Ribs spaced 12 inches apart
- 1.25-inch rib height
The look is more industrial than corrugated. Clean lines rather than waves.
Strength Characteristics
The trapezoidal ribs provide:
- Higher strength and rigidity than corrugated
- Better spanning capability between supports
- Greater resistance to foot traffic
- Superior performance under snow and wind loads
R-panel’s deeper, angular ribs create a stronger panel pound-for-pound.
Common Applications
R-panel works well for:
- Commercial and industrial buildings
- Metal building systems
- Agricultural buildings requiring greater spans
- Residential projects where strength matters
- Post-frame construction
- Buildings with wider purlin spacing
Material Options
R-panel comes in similar materials as corrugated:
- Galvanized or Galvalume steel (most common)
- Pre-painted steel (many colors)
- Aluminum (where corrosion resistance matters most)
R-panel more commonly comes in painted finishes than corrugated, reflecting its broader commercial use.
Head-to-Head Comparison
| Factor | Corrugated | R-Panel |
|---|---|---|
| Strength/Rigidity | Moderate | Higher |
| Weight | Similar | Similar |
| Walk-ability | Fair | Better |
| Cost | Lower | Slightly higher |
| Appearance | Rustic, agricultural | Industrial, commercial |
| Spanning Capability | Limited | Greater |
| Snow/Wind Resistance | Good | Better |
| Installation | Simple | Simple |
| Availability | Very common | Very common |
Cost Comparison
For a typical 1,500 square foot roof (small barn or workshop):
Corrugated (29-gauge galvanized)
- Materials: $1,800 – $2,400
- Installation: $1,500 – $2,500
- Total: $3,300 – $4,900
R-Panel (26-gauge painted)
- Materials: $2,400 – $3,200
- Installation: $1,800 – $2,800
- Total: $4,200 – $6,000
R-panel typically costs 20-30% more than equivalent corrugated. The difference comes from:
- Deeper panel profile uses more material
- Painted finishes cost more than galvanized
- Heavier gauges common in R-panel add cost
For larger structures, the cost gap can be meaningful. For smaller projects, the difference may be a few hundred dollars.
Weather Performance in WNC
Rain and Water Management
Both handle rain adequately, but their profiles manage water differently.
Corrugated: Water flows in the valleys between ridges. The curved shape can slow water flow slightly. Debris can accumulate in valleys.
R-Panel: Water flows in the flat pans between ribs. The angular shape moves water more efficiently. Flat pans are easier to clear.
Both require proper slope and sealing at overlaps. Neither is waterproof at seams without appropriate sealant.
Wind Resistance
Corrugated: Panels can flutter in high wind. The rounded profile catches wind slightly more than angular profiles. Fastener pull-out is the primary failure mode.
R-Panel: More rigid panels resist flutter better. Angular profile is more aerodynamic. Still relies on fastener integrity in severe wind.
For WNC mountain wind exposure, R-panel’s greater rigidity provides some advantage.
Snow Load
Corrugated: Adequate for typical residential snow loads. Panels can deflect under heavy accumulation. May require closer purlin spacing in heavy snow areas.
R-Panel: Stronger spanning capability handles heavier loads. Better suited for higher elevations with substantial snowfall. Can span wider purlin spacing.
Hail
Both dent from hail impact. Neither achieves the Class 4 impact ratings that quality standing seam achieves. Dents are cosmetic but affect appearance.
Durability and Lifespan
Expected Lifespan
Corrugated: 20-35 years depending on gauge, coating, and maintenance
R-Panel: 25-40 years depending on gauge, coating, and maintenance
Both fall well short of standing seam’s 50-70 year potential, but both outlast asphalt shingles.
Fastener Maintenance
The limiting factor for both is typically fastener deterioration, not panel deterioration.
Exposed fastener washers compress over time. Temperature cycling causes expansion and contraction that can loosen screws. Eventually, fasteners need replacement or re-sealing.
Maintenance schedule:
- Inspect fasteners annually
- Expect re-tightening or replacement starting around year 15-20
- Replace deteriorated washers before leaks develop
Proper maintenance extends life. Neglected fasteners become leak points.
Coating Durability
Galvanized: Natural weathering appearance develops over time. No paint to fade, but zinc coating eventually depletes.
Galvalume: Better long-term corrosion resistance than galvanized. Can develop some staining over time.
Painted: Appearance holds better initially. Quality paint systems (PVDF/Kynar) last longer than basic polyester. Fading and chalking develop over time.
Choosing Between Them
Choose Corrugated If:
✓ Budget is the primary driver
✓ Agricultural or rustic aesthetic fits your project
✓ The building is a barn, shed, or outbuilding
✓ Purlin spacing is relatively close (24″ or less)
✓ You like the traditional corrugated look
✓ Maximum economy matters more than maximum strength
Choose R-Panel If:
✓ Greater strength and spanning capability matter
✓ You need to walk on the roof for maintenance
✓ The building has wider purlin spacing
✓ Industrial or commercial appearance is appropriate
✓ Snow loads are significant
✓ You want better long-term rigidity
Either Works If:
- Your structure is a standard barn, workshop, or outbuilding
- Budget and appearance preferences don’t strongly favor one
- You’re getting quality products in either profile
When to Choose Neither
Exposed fastener metal roofing, whether corrugated or R-panel, isn’t right for every application.
Consider Standing Seam Instead If:
- This is your primary residence
- Maximum lifespan matters
- You want minimal maintenance
- Appearance is a priority
- Budget allows the investment
- You want insurance premium benefits
Consider Shingles Instead If:
- Traditional residential appearance is required
- Budget doesn’t allow any metal option
- HOA prohibits metal roofing
Installation Considerations
Both corrugated and R-panel install similarly:
- Install purlins or solid deck
- Apply underlayment (recommended)
- Lay panels starting at one edge
- Overlap panels per manufacturer specs
- Fasten with screws and washers at specified spacing
- Install ridge cap and trim
Key differences:
- R-panel’s deeper ribs require slightly different ridge and trim details
- Corrugated’s curves need compatible closure strips
- Both require proper screw placement (in flat areas, not rib tops, for most applications)
Professional installation ensures proper sealing, fastener patterns, and detail work.
Our Recommendations
For most WNC residential outbuilding projects, we suggest:
Barns, equipment storage, carports: Corrugated galvalume offers good value. If appearance matters, painted corrugated or R-panel.
Workshops, garages, higher-use buildings: R-panel provides better strength and walk-ability for buildings you’ll access regularly.
Budget residential primary structures: If you want metal on a tight budget and the look works, corrugated can serve. But consider whether the long-term math favors standing seam.
Any structure with significant spans or loads: R-panel’s strength handles more demanding applications.
Get Expert Guidance
Secure Roofing installs corrugated, R-panel, and standing seam metal roofing throughout Western NC. We can help you determine which makes sense for your specific project.
Call 828-888-ROOF for a free consultation and quote.
Related Articles:
- Metal Roofing Costs in Western NC
- Metal Roofing vs. Asphalt Shingles
- Standing Seam Metal Roofing Guide
- Metal Roofing Services
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