Metal Roofs in Los Angeles.

Metal roofs for homes come in two broad styles. Standing-seam roofs use long panels joined by raised seams. Stone-coated steel roofs use stamped panels covered in granules, made to look like tile, shake or shingles. This page compares the two using one maker's published data for each. Part of our roof types hub.

We use Metal Sales (Magna-Loc standing seam) and DECRA (stone-coated steel) as examples only because both publish full data sheets. LA Roof Guide does not sell, install or recommend any product. Other brands publish different numbers.

Thickness: gauge vs. inches

Metal roofing has long been sold by "gauge," where a smaller number means thicker metal. Metal Sales says the industry "is moving away from 'gauge' to decimal thickness in inches." It recommends a minimum of 0.0230 inch in place of 24 gauge and 0.0296 inch in place of 22 gauge.

For Magna-Loc, Metal Sales lists two base metals:

• Steel coated with an aluminum-zinc alloy (Galvalume), at 0.0230 or 0.0296 inch minimum thickness. It says to specify an AZ50 coating for painted steel or AZ55 for unpainted steel.
• Aluminum sheet at 0.032 inch nominal thickness.

What to ask: if a bid lists only a gauge, ask for the thickness in inches and the coating designation.

Roof pitch limits

The two styles fit very different roofs.

A pitch of 1/2:12 means the roof rises half an inch for every 12 inches of run. So the standing-seam panel is listed for nearly flat roofs, while the stone-coated panels need a steeper roof.

Panel size and weight

Magna-Loc panels cover 16 or 18 inches in width, with a 2-inch rib. They attach with concealed clips that Metal Sales says are "designed for thermal movement," since metal expands and shrinks with heat.

DECRA lists an installed weight of 150 lb per square (100 square feet) for most of its profiles and 160 lb for Villa Tile. That is far lighter than the concrete tile figures on our shingle vs. tile page. The Metal Sales sheet does not list a weight.

Fire, hail and wind ratings

Note the DECRA fire line. It lists Classes A, B and C, but the sheet does not say which installation earns Class A. In a fire hazard zone, ask for the Class A listing for the exact profile and installation in writing. Our page on Class A roofs and vents explains the fire zone rules, including how the space under some roof profiles has to be closed off.

The California Department of Insurance's Safer from Wildfires program lists a "Class-A fire rated roof" as one of its steps. It says most roofs qualify, including "metal shingles or sheets." The department says "Every action under Safer from Wildfires will qualify you for an insurance discount." Ask your insurer how it applies to your policy.

Coatings and cool colors

Metal Sales lists a PVDF (Kynar 500) or acrylic coated Galvalume finish. DECRA lists a steel core with an aluminum-zinc hot dip coating, an acrylic primer and basecoat, ceramic coated stone granules and an acrylic over-glaze.

The Energy Commission says tile, metal, asphalt and coatings can all meet cool roof rules, in "light, dark, and vibrant shades." DECRA names three cool roof colors (Royal Oak, Mist Grey and Spanish Clay) that it says "meet California Title 24 Cool Roof requirements." Metal Sales lists the Cool Roof Rating Council among its approval bodies. For when a reroof must meet the cool roof rules, see Cool roofs in California.

Warranty fine print

Warranty terms differ a lot between these two makers.

Metal Sales (standing seam):

• Paint finish: 45 years for film integrity and 35 years for chalk and fade, under its standard PVDF warranty.
• Weather tightness: optional periods of 5, 10 or 20 years, in several warranty types. Some have a dollar limit and some do not.
• Exclusions: the paint warranty excludes "failure due to physical damage and exposure to salt environments." The weather tightness warranty excludes "physical damage and surface deterioration due to exposure to salt environments." If your home is near the ocean, ask the seller how the warranty defines a salt environment.
• Touch-up paint: Metal Sales warns that touch-up paint "will not weather as well or at the same rate as the original system."

DECRA (stone-coated steel):

• A Lifetime Limited Warranty that DECRA says applies only to "single family detached residential property in the U.S. & Canada."
• A 120 mph wind speed warranty and a hail stone penetration warranty.

What to ask: get the full warranty document for the exact product, not the summary on a data sheet.

Solar on a metal roof

Metal Sales recommends "S-5! non-penetrating systems for the attachment of snow guards and solar panels" on its standing-seam roofs. The maker describes these as non-penetrating. If solar is planned, ask how the mounts attach and whether the method affects the roof warranty.

Local code listings

DECRA's sheet says its products meet International Code Council requirements, including the City of Los Angeles building and residential codes (LABC, LARC). It lists two ICC evaluation reports, each naming certain profiles: ESR-2901 (Tile, Shake, Shingle Plus on battens) and ESR-1754 (Villa Tile, Shake XD, Shingle XD, Shingle Plus direct to deck). Ask which report covers the exact profile and installation on a bid. Your building department decides what it accepts.

A checklist for a metal roof bid

Ask for each of these in writing:

1. The maker, product name and color.
2. Metal thickness in inches, base metal (steel or aluminum) and coating.
3. Minimum pitch for the product, and your roof's pitch.
4. Fire class for the exact installation, plus hail and wind ratings.
5. CRRC product ID if a cool roof is required.
6. The full paint and weather tightness warranties, including any coastal or salt exclusions.

Back to Roof types.

This is general information, not engineering or building code advice. Rules differ by city. Check with your local building department.