Reviewed by The Roofing Brief Team. Last reviewed: October 2026.
Metal roofs are made of one of five base metals: steel, aluminum, copper, zinc, or stainless steel. Steel is the most common by far, and the building code sets the floor for each: galvanized steel must carry at least a G90 zinc coating and aluminum-zinc (Galvalume) steel at least AZ50, per IRC Table R905.10.3(2) in the 2021 code as printed in the 2021 Seattle Residential Code, Chapter 9. Every metal roof starts as flat sheet rolled off a coil, gets a corrosion-fighting layer (a metallic coating or the metal’s own oxide), and then usually a baked-on paint finish before it is roll-formed into panels, shingles, or tiles. The metal underneath decides cost, weight, and service life: installed prices run from $500 to $1,300 per 100 sq ft roofing square for galvanized or Galvalume steel up to $1,300 to $3,000 for copper, per HomeGuide’s metal roof cost guide (November 21, 2025).
What metals are used in metal roofing?
Five metals cover nearly all residential and commercial metal roofing: steel, aluminum, copper, zinc, and stainless steel. The IRC names a material standard for each one in Table R905.10.3(1): ASTM A924 or A653 for steel, ASTM B209 for aluminum, ASTM B370 for copper, ASTM A240 300 series for stainless, and a 0.027 in minimum for zinc. Copper, zinc, and stainless steel are the premium options, priced at $1,000 to $3,000 per installed square in HomeGuide’s table, against $500 to $1,300 for coated steel.
| Metal | What it actually is | Typical sheet thickness | Code minimum (IRC Table R905.10.3) | Corrosion protection | Installed cost per square (HomeGuide, Nov 2025) |
|---|---|---|---|---|---|
| Steel | Iron-carbon alloy sheet | 29 to 24 gauge | ASTM A653 G90 (galvanized) or ASTM A792 AZ50 (Galvalume) | Zinc or aluminum-zinc metallic coating plus paint | $500 to $1,300 ($5 to $13 / sq ft) |
| Aluminum | Aluminum-manganese alloy (3000 series, often 3105) | 0.032 to 0.040 in | ASTM B209, 0.024 in minimum for roll-formed panels | Natural oxide layer plus paint | $700 to $1,700 ($7 to $17 / sq ft) |
| Copper | 99.9% copper sheet (ASTM B370) | 16 to 20 oz / sq ft (0.0216 to 0.0270 in) | ASTM B370, 16 oz/sq ft (12 oz high-yield) | Self-forming green patina | $1,300 to $3,000 ($13 to $30 / sq ft) |
| Zinc | 99.995% zinc with copper and titanium additions | 0.65 to 1.0 mm (RHEINZINK standard range) | 0.027 in minimum | Self-healing patina | $1,000 to $2,000 ($10 to $20 / sq ft) |
| Stainless steel | Iron alloyed with 10.5%-plus chromium (304 or 316) | 26 to 24 gauge | ASTM A240, 300 series | Chromium oxide layer | $1,000 to $2,100 ($10 to $21 / sq ft) |
HomeGuide’s per-square prices move most with panel profile: it puts standing seam at $9 to $16 per square foot installed against $5 to $12 for corrugated sheet, and labor alone at $4 to $8 per square foot. Thicker gauge (a lower gauge number) means more metal and a higher price, which is why a 24 gauge standing seam roof costs more than a 29 gauge exposed-fastener panel of the same metal. The IRC equates No. 26 galvanized sheet gage with a 0.019 in minimum for tile valley flashing (R905.3.8), a useful reference point when comparing quotes.
Which roofing metal fits your roof: decision table
| If your roof… | Use | Threshold or rule (source) |
|---|---|---|
| Has a budget near $5 to $13 per sq ft installed | Galvalume or galvanized steel | $500 to $1,300 per square (HomeGuide); code floor AZ50 or G90 |
| Is pitched below 3:12 | Standing seam, not lapped exposed-fastener panels | IRC R905.10.2: standing seam down to 1/4:12; lapped panels need 3:12, or 1/2:12 with lap sealant |
| Sits in a salt-air coastal zone | Aluminum, ideally with a coastal PVDF warranty | Sheffield Metals offers a 35-year coastal PVDF warranty on aluminum only; its standard paint warranties exclude locations near the coastline |
| Is a copper roof | Copper, brass, bronze or 300-series stainless fasteners | IRC R905.10.4, item 2 |
| Uses copper pans wider than 24 in | 20 oz copper instead of 16 oz | Copper Development Association batten-seam detail: 16 oz for pans up to 20 in, 20 oz above 24 in |
| Needs the look of tile or shake at 3:12 or steeper | Stone-coated AZ50 steel | DECRA Tile: 20 panels per square at 6.06 lb each, minimum pitch 3:12 (DECRA components chart) |
| Must hold its color for decades | PVDF (Kynar 500 or Hylar 5000) over SMP | Both carry 40-year film warranties; PVDF has tighter chalk and fade limits (Sheffield Metals) |
What is steel roofing made of?
Steel roofing is an iron-carbon alloy sheet with a metallic anti-corrosion coating bonded to both faces, then painted. Bare steel rusts, so the coating is what lets it survive on a roof, and the IRC lists four accepted coatings in Table R905.10.3(2): ASTM A792 AZ50 aluminum-zinc, ASTM A875 GF60, ASTM A463 T2 65 aluminum-coated, and ASTM A653 G90 galvanized. Two of these dominate roofing: galvanized (pure zinc) and Galvalume (an aluminum-zinc blend). The steel core is the same; the coating chemistry is the difference that matters.
- Galvanized steel: coated with 100% zinc. The roofing benchmark is G90, which carries a minimum of 0.90 oz of zinc per square foot of sheet, total for both sides, per GalvInfo Center’s note on ASTM A653 coating designations. Zinc protects sacrificially, corroding before the steel does, especially at cut edges.
- Galvalume (also sold as Zincalume): coated with an alloy of 55% aluminum, 43.4% zinc, and 1.6% silicon, per DECRA’s coated-steel specification page. AZ50 means at least 0.50 oz of coating per square foot, both sides combined, and DECRA states its panels use ASTM A792 Grade 37 steel at AZ50.
For a full side-by-side on the two coatings and how gauge affects price, see our breakdown of galvanized versus Galvalume steel and gauge.
What are aluminum, copper, zinc, and stainless steel roofs made of?
The four non-steel metals each resist corrosion on their own, so they skip the metallic coating that IRC Table R905.10.3(2) requires on steel. Their composition explains why HomeGuide prices them at $700 to $3,000 per installed square, against $500 to $1,300 for coated steel.
- Aluminum is an aluminum-manganese alloy in the 3000 series; Sheffield Metals states it uses 3105. It forms a thin oxide layer the moment it meets air, so it never rusts and needs no zinc coating, only paint for color. PAC-CLAD lists its Snap-Clad panel in 0.032 in and 0.040 in aluminum, above the IRC’s 0.024 in minimum for roll-formed aluminum.
- Copper roofing sheet is 99.9% copper under ASTM B370, per the Copper Development Association’s architectural handbook, and is sold by weight: 16 oz per square foot is 0.0216 in thick. It develops a green patina over time that seals the surface; the CDA notes the process runs faster in marine, urban and industrial air.
- Zinc roofing is 99.995% pure primary zinc with small additions of titanium and copper, per RHEINZINK, which rolls standard sheet from 0.65 mm to 1.0 mm. The IRC’s zinc entry sets 0.027 in as the minimum and lists copper at 0.08% to 0.20% and titanium at 0.07% to 0.12%. Its patina closes over light scratches over time.
- Stainless steel is iron alloyed with at least 10.5% chromium; the IRC accepts ASTM A240 300 series alloys, typically type 304 or the more corrosion-resistant 316. The chromium forms a passive oxide film that reseals if scratched. Terne-coated stainless adds a tin-based matte finish, and the IRC sets terne at 40 lb per double base box.
Each of these has its own cost and lifespan profile. Our guides to aluminum roofing cover where the lighter metal earns its premium.
What are metal roof tiles and shingles made of?
Most metal roof tiles and shingles are made of stone-coated steel: AZ50 aluminum-zinc coated steel, an acrylic resin layer, and crushed stone granules baked on with pigment, per DECRA’s explainer on its own panels. The stone layer gives the look of tile, shake or shingle. DECRA’s components chart lists DECRA Tile at 20 panels per square and 6.06 lb per panel, about 121 lb per square, with a 3:12 minimum pitch. Stamped metal tile without stone uses a painted core instead: Mueller’s ProVia metal barrel tile is G90 steel with a zinc phosphate coat and a Kynar 500 finish, rated Class 4 for hail and 130 mph for wind.
What coatings and paint finishes go on a metal roof?
A painted steel roof is built in layers: steel core, metallic coating, pretreatment, primer, and a colored topcoat, with a thin backer on the underside. The IRC footnote to Table R905.10.3(2) requires paint systems under ASTM A755 to go over steel that already carries an A792, A875, A463 or A653 coating. The paint chemistry, not the color, decides how long the finish holds up.
| Paint system | What it is | Fade and chalk resistance | Example warranty (Sheffield Metals) | Best for |
|---|---|---|---|---|
| SMP | Silicone-modified polyester | Moderate | 40 years film adhesion; 30 years chalk and fade, at looser limits than PVDF | Budget panels, agricultural and outbuildings |
| PVDF (Kynar 500 / Hylar 5000) | Fluoropolymer resin, at least 70% PVDF by weight in Kynar 500 finishes | Highest available | 40 years film adhesion; 30 years chalk and fade; 35-year coastal option on aluminum | Homes and commercial where color must hold |
PVDF, marketed under the Kynar 500 and Hylar 5000 names, is the premium finish; Arkema’s Kynar 500 specification requires licensed finishes to contain at least 70% Kynar 500 resin by weight. Per Sheffield Metals’ warranty comparison, both systems carry 40-year film adhesion coverage, so ask for the chalk and fade limits in delta units. On bare copper, zinc, and stainless roofs, there is often no paint at all, since the metal is left to patina naturally.
Are metal roofs actually made of tin?
Almost no modern metal roof is made of tin. The phrase tin roof is a holdover from the 1800s and early 1900s, when roofs were made of terne, a steel or iron sheet coated in a tin-lead alloy. The IRC still lists terne and terne-coated stainless in Table R905.10.3(1), at 40 lb of coating per double base box, but today a so-called tin roof is nearly always galvanized or Galvalume steel. HomeGuide prices tin (terne) roofs at $600 to $1,800 per installed square.
True tin was never structural on its own. It was a thin protective coating over a stronger base metal, much like zinc coats galvanized steel now. If someone quotes you a tin roof, ask for the coating designation (G90 or AZ50) and the gauge, such as 26 gauge, in writing, because it is almost certainly coated steel or aluminum. Our guide to the corrugated tin roof explains what those panels really are and what they cost.
How is metal roofing made?
Metal roofing is manufactured from coil, not cast or cut from thick plate. The mill starts with a rolled coil of steel or aluminum and coats and paints it before it reaches a roll former; RHEINZINK, for example, ships zinc in coils of up to 5 tonnes (about 11,000 lb) and sheets up to 6 m (about 19.7 ft) long. The process is why panels arrive pre-colored and consistent.
- Coil production. Steel or aluminum is cold-rolled into thin sheet and wound into coils, each weighing several tons.
- Metallic coating. Steel coil passes through a molten zinc or aluminum-zinc bath to become galvanized or Galvalume. Aluminum, copper, and zinc skip this step.
- Paint line. The coil is cleaned, pretreated, primed, and coated with a baked-on SMP or PVDF topcoat, then oven-cured.
- Roll forming. The finished coil feeds through a roll former that bends it into the panel profile, whether standing seam, exposed-fastener, or a stamped metal shingle or tile; PAC-CLAD’s Snap-Clad profile, for example, comes off the former with a 1-3/4 in leg height.
- Cut to length. Panels are sheared to the exact roof dimension, often on site for standing seam; PAC-CLAD lists Snap-Clad panels up to 64 ft long, so runs can span a slope with no horizontal seam.
For the full range of shapes this process produces, see our guide to metal roofing types, panels, and profiles.
Which metal roofing material is most common?
Steel is the most common metal roofing material, and metal as a whole runs a distant second to asphalt shingles on U.S. homes. Steel wins on cost: HomeGuide prices galvanized and Galvalume at $100 to $500 per square for material, against $300 to $900 for aluminum and $900 to $2,000 for copper. Aluminum is the usual coastal pick, and the specialty metals stay niche.
For the U.S. split by material, see our roofing material market share report and our roofing basics learning hub.
Frequently asked questions
What are metal roofs most commonly made of?
Most metal roofs are made of steel coated with zinc (galvanized, G90 minimum) or an aluminum-zinc alloy (Galvalume, AZ50 minimum) to stop rust, then painted. Steel dominates because it costs the least, $500 to $1,300 per installed square per HomeGuide. Aluminum is favored near salt water, while copper, zinc, and stainless steel are premium metals at $1,000 to $3,000 per square.
Are metal roofs made of steel or aluminum?
Both, though steel is far more common. Steel is cheaper and stronger but needs a zinc or aluminum-zinc coating to resist rust. Aluminum costs more, $700 to $1,700 per installed square per HomeGuide, weighs less, and never rusts because it forms its own oxide layer, which is why it is the usual choice in salt-air coastal zones.
What is Galvalume made of?
Galvalume is steel sheet coated with an alloy of 55% aluminum, 43.4% zinc, and 1.6% silicon by weight. The aluminum gives long flat-surface corrosion resistance and the zinc protects cut edges. It is sold as Galvalume or Zincalume in grades such as AZ50, which means at least 0.50 oz of coating per square foot, both sides combined.
What are most metal roof tiles made of?
Most metal roof tiles are made of stone-coated steel. DECRA, for example, builds its tiles from ASTM A792 steel with an AZ50 aluminum-zinc coating, an acrylic resin layer, and baked-on stone granules. DECRA Tile weighs about 121 lb per square (20 panels at 6.06 lb each) and needs at least a 3:12 pitch.
Are metal roofs actually made of tin?
No. The term tin roof dates to the era of terne, a steel sheet coated in a tin-lead alloy. Modern panels called tin roofs are almost always galvanized or Galvalume steel, or sometimes aluminum. Pure tin was never a structural roofing metal on its own, only a coating; the IRC still lists terne at 40 lb of coating per double base box.
Do metal roofs rust?
Bare steel rusts, which is why the IRC requires roofing steel to carry at least a G90 zinc or AZ50 aluminum-zinc coating, usually painted. Aluminum, copper, zinc, and stainless steel do not rust, because each forms a protective oxide or patina layer on its own. Sheffield Metals lists dissimilar-metal contact and sites near the coastline among the exclusions in its paint warranties.
What is the best metal for a roof?
Match the metal to the budget and the site. Galvalume or galvanized steel at $5 to $13 per sq ft installed suits most inland homes. Aluminum at $7 to $17 is the usual coastal pick. Copper at $13 to $30 and zinc at $10 to $20 suit high-end architecture, and 300-series stainless handles harsh industrial exposure.