How to Install Metal Roofing Sheets

Install wood furring strips in a horizontal orientation across the rafters of the roof. Unlike asphalt roofing, metal roofing sheets don't require solid sheathing under them. Use 1-by-4-inch boards for the furring strips, separating them with 4-inch spaces. This saves on material and enhances air circulation around the metal.

Lay a metal roofing sheet on one side of the roof beside the gable end, with its bottom edge level with the eaves. Screw the metal sheet onto the wood strips with 2-inch-long roofing screws equipped with rubber gaskets. Don't put the screws into the flat parts of the metal between the ridges, because that would increase the risk of a leak. Put a screw in every 12 inches in the top of the ridge that runs up the side of the roof next to the gable end. Put another row of screws in the ridge running up the middle of the sheet. Don't screw the other side of the sheet down until you put the next sheet on top of it in Step 3.

Lay a second metal roofing sheet next to the first so its edge overlaps the edge of the first sheet. Put screws through the joined edges of the sheets and into the furring strip below with roofing screws driven in at 12-inch intervals running up the pitch of the roof.

Continue laying metal roofing sheets across the surface of the roof until you arrive at the other gable end of the roof. If the last sheet doesn't match the last space, cut the sheet to the appropriate width for the space with a circular saw and a metal cutting blade.

Install a second course of metal sheets above the first if the roof is so large that the first course of metal sheets doesn't reach the ridge. Place the bottom edge of the second course of sheets low enough that these sheets overlap the top of the first course by at least 12 inches. This ensures that no water can creep up over the bottom sheets and damage the roof.

Install a top cap along the ridge once you have laid all of the metal roofing sheets on both faces of the roof.