Types of metal roofing: the panels, the metals, and the lowest pitch for each
Metal roofs come as panels or as shingles. Panels are either standing seam, locked together at raised seams with the fasteners hidden, or lapped ribbed and corrugated panels screwed through the face. The metals the building code lists are coated steel, aluminum, copper, zinc, stainless steel, lead and terne. Standing seam can go down to a 1/4:12 pitch; lapped panels without sealant need 3/12.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
Reading as
Panels and shingles
| Type | What it is | Lowest pitch in the code |
|---|---|---|
| Standing seam | Long panels joined at raised seams, the fasteners hidden under them | 1/4:12 (R905.10.2) |
| Ribbed panels | Lapped panels with square ribs, screwed through the face | 3/12, or 1/2:12 with lap sealant (R905.10.2) |
| Corrugated panels | Lapped panels with rounded waves, screwed through the face | 3/12, or 1/2:12 with lap sealant (R905.10.2) |
| Metal shingles | Pressed metal made to look like shingles, slate, shakes or tile | 3/12 (R905.4.2) |
- Standing seam panels run from the eave to the ridge in one piece. The seams stand up off the roof, and the code lets standing seam go on the lowest slopes of any metal roof.
- Ribbed and corrugated panels lap over each other at the edges, and the screws go through the panel with a washer.
- Metal shingles go on in courses like other shingles, and need the same steeper pitch as wood shingles.
The code calls for metal panels on solid or spaced sheathing, unless they’re made for spaced supports (R905.10.1), and for underlayment under them (R905.10.5).
The metals
The building code lists these metals for metal sheet roofs, each made to its standard (Table R905.10.3(1)):
| Metal | Standard and minimum |
|---|---|
| Galvanized steel | ASTM A653, G90 zinc coating |
| Steel | ASTM A924 |
| Stainless steel | ASTM A240, 300 series |
| Aluminum | ASTM B209, 0.024 inch for roll-formed panels |
| Copper | ASTM B370, 16 ounces a square foot for sheet roofs |
| Zinc | 0.027 inch, high-grade zinc alloy |
| Lead and lead-coated copper | Hard lead 2 pounds a square foot; soft lead 3 |
| Terne (tin) | Terne coating of 40 pounds per double base box |
Steel has to be made corrosion resistant. Besides galvanized (zinc coated), the code lists 55% aluminum-zinc alloy coated steel (ASTM A792, AZ50) and aluminum-coated steel among the coatings (Table R905.10.3(2)).
Gauge
Steel roofing is sold by gauge: the lower the number, the thicker the steel. Ribbed steel panels come in 29, 26 and 24 gauge.
What a metal roof costs
The metal roof cost guide prices ribbed 26 gauge steel panels on three typical houses, shingles torn off, by state: about $23,500 to $37,750 on a 1,800 sq ft one-story house, typically $29,250. Totals include the contractor’s overhead and profit (20%) and the state’s average sales tax.
Common questions
Is 24 or 26 gauge better for a metal roof?
24 gauge is thicker and stiffer than 26 and costs more. Which one a roof needs depends on the panel, the spans and the wind loads in the maker’s specifications.
Can metal roofing go on a low-slope roof?
Standing seam can go down to 1/4:12, and lapped panels with sealant to 1/2:12. Lapped panels without sealant need at least 3/12 (IRC R905.10.2).
Can a metal roof go over shingles?
Often, over one layer, when the panel maker’s instructions allow it, and standing-seam systems that carry their own load don’t need the old roof taken off (IRC R908.3.1). The metal roof cost guide has the details.