How to Put a Metal Roof on a House

Check with your local building department, which might require permits and other conditions on metal roofing. Building codes vary by jurisdiction, but they all stem from the International Residential Code managed by the International Code Commission. Chapter 9 covers roof assemblies, with metal roof panels detailed in 905.10.

Read the manufacturer’s instructions for preparation and installation of the panels. Methods vary by roof style. The following procedures generally apply to ribbed roof panels.

Prepare the bare roof deck, which requires the underlayment specified by local building codes and the IRC. For example, in high-wind areas, a typical underlayment is 30-pound building felt, overlapped by not more than 36 inches on center. Acceptable fasteners include corrosion-resistant nails with enough length to penetrate through either the entire sheathing or at least 0.75 inches into it, whichever is shorter.

Attach 1-by-4-inch strips of wood over the felt and into the sheathing using corrosion-resistant fasteners such as roofing nails. Space them about 24 inches apart on-center.

Add flashing across the eaves if your roof is going to have a gutter. Close the gap between the flashing and the roofing panels with inside-closure strips. Apply a bead of sealant, such as butyl tape sealant, to the top of the strip. The metal panels will join this adhesive when placed over the strip.

Attach the metal roofing panels, perpendicular to the wood strips, until the roof deck is covered. Use self-tapping gasket-head wood screws and space them about 12 inches apart throughout the length of the wood strip. The first panel must overhand the eaves by about 0.75 inches. Each additional panel must overlap the ridges of the previous panel.

Put flashing over the front and back edges of the roof. Use a bead of sealant along the line between the flashing and the roof panel. Then drive a row of wood screws through the flashing, tape sealant, roof panel and into the sheathing. If you have to use several lengths of flashing, ensure that they overlap by at least 2 inches and are sealed with tape sealant.

Install the peak flashing at the highest point of the roof. This construction can cover the joint of a gable roof, or the highest edge of a shed roof. Its purpose is to prevent water from entering the highest joint of the assembly. Use a bead of sealant in a line between the flashing and the roof panel. Then add more sealant on top of the closure strip and put the peak flashing over the strip. Use metal stitch screws to attach the flashing to the roof panels.