Metal Roofing Services
The panel type decides how low a slope the roof can have and how it's fastened.
Standing-Seam Metal Roofs
Standing-seam panels join along raised seams, with the fasteners hidden under the seam or in concealed clips. The code allows standing-seam systems on slopes as low as ¼ inch per foot. The panels still go over underlayment, and the flashing at walls, valleys and openings has to be detailed to let the metal expand and contract.
Exposed-Fastener Metal Panels
Exposed-fastener panels are screwed through the face of the panel, with a washer under each screw head. Lapped panels with non-soldered seams need a slope of at least 3:12 without lap sealant, or ½:12 with sealant applied to the manufacturer's instructions. They're used on patio covers, carports and outbuildings as well as main roofs.
Metal Roof Repair and Coating
Metal roof repairs replace loose or worn fasteners and washers, reseal laps, fix flashing and trim, and treat rust at cut edges and fasteners. The code allows a new protective coating over an existing metal panel or metal shingle roof without a tear-off, as long as the roof isn't deteriorated past serving as a base. See roof coating.
Why Tempe homeowners call Tempe Expert Roofing
- Free, no-obligation roof estimates
- Written scope: tear-off, underlayment, flashing, coating
- Photos of every finding on your roof
- Permit and code questions answered up front
- One call, one local roofer
What Affects the Cost of a Metal Roof
Panel type
Standing seam or exposed fastener.Material and coating
Aluminum-zinc coated, galvanized, prepainted or aluminum.- Roof area, pitch and complexity.
- Tear-off of the existing roof.
- Flashing, trim and penetrations.
Metal Roof Materials and Corrosion Standards
The code sets minimum corrosion resistance for steel roof panels and minimum thickness for others. When you compare quotes, the material line should name one of these:
| Material | Standard |
|---|---|
| 55% aluminum-zinc alloy-coated steel | ASTM A792 AZ 50 |
| Galvanized steel | ASTM A653 G-90 |
| Prepainted steel | ASTM A755 paint over one of the coated steels above |
| Aluminum panels | ASTM B209, at least 0.024 inch for roll-formed panels |
Valley flashing on metal roofs has to be corrosion-resistant metal of the same material as the roof covering, or one of the listed materials, extending at least 8 inches each way from the centerline with a splash diverter rib at least ¾ inch high.
A light, reflective paint finish helps keep attic heat down under the Phoenix-area sun. Switching an existing roof to metal changes the roof covering class and weight, so check whether it needs a Tempe permit. See roof replacement.