How to Put on a Steel Roof

Measure the distance from the peak to the eaves on your roof. If this distance is longer than a sheet of roofing, begin at the eaves and add a second row of roofing that overlaps the first at the peak.

Lay a sheet of roofing onto the roof at one gable end, being sure that the edge of the steel roofing overhangs the top of the fascia on the gable end, and that the roofing is parallel with the edge of the roof. If sheathing is present from a previous roof, you can lay steel roofing on top of it. If it is a new roof, the rafters or trusses should have horizontal cross pieces laid down to receive the steel roofing, although they don't need to be continuous. Four-inch wide boards separated by 4-inch spaces are sufficient to support steel roofing. A layer of tar paper should be laid over the boards and underneath the steel roofing as a backup against water infiltration.

Secure the steel roofing to the roof using a 2-inch long roofing screw that is equipped with a rubber gasket. You can do this with a standard drill, but it's much easier with a clutch drill. You can set a clutch drill to stop when the screw reaches a certain pressure, a feature that allows you to put the screws in just enough to compress the rubber gasket. Apply screws every 12 vertical inches along the raised ridges on the steel. Never apply a screw to the flat of the steel, as this increases the risk of a leak. Don't put screws into the last ridge because you will be overlapping the next sheet onto it. If you will be adding a second row of steel roofing above the first, don't put any screws into the top 12 inches of the sheets yet.

Put the second sheet of roofing down with its edge ridge overlapping the edge ridge of the first sheet of steel. Screw it down in the same way you screwed down the first sheet.

Continue adding sheets across the span of the roof until you reach the other end. If a full sheet doesn't fit at the end of the roof, cut a sheet lengthwise using a circular saw fitted with a metal cutting blade.

Add a second row of metal sheets if the height of the roof requires it. Overlap the tops of the first row by 12 inches to ensure that water doesn't creep up and underneath the tops of the bottom row of sheets.

Install a steel cap onto the ridge after you have finished installing the steel roofing sheets on both sides of the peak. Purchase a peak that is custom made for the type of roofing you are using; the peak will be made with openings to accommodate the ridges in the steel so that the peak sits flat at the point of the roof.