Corrugated metal roofing is either aluminum or galvanized steel. It is used mainly on sheds, barns and similar buildings. It is rarely used on residential roofs, because it is harder to insulate properly. There are many corrugation patterns, with the height and width of the peaks and valleys varying. The standard is 2 1/2 by 1/2, with corrugation peaks 2 1/2 inches apart and the overall height 1/2 inch. This style comes in sheets 27 inches wide, designed to cover 24 inches of roof, allowing for overlap of panels on the edges, in panels from 8 to 20 feet long.
Things You'll Need
- Tape measure
- 1-by-4-inch strip sheathing
- 8d galvanized nails
- Roofing paper
- Galvanized or aluminum screws with plastic washer cap
- Screw gun
- Tin snips (optional)
- Ridge caps and edge caps
Measure the roof with a tape measure to determine the number of panels needed. Try to buy panels in lengths that will cover each side of the roof with one panel, to simplify installation; use 12-foot panels, for instance, if the distance from peak to edge is about 12 feet, allowing for some overlap at the bottom. Divide the width by the coverage of the panel, typically 24 inches.
Install corrugated panels either on solid decking or "strip" sheathing, which are 1-by-4-inch boards nailed horizontally across rafters, or truss chords at 24-inch intervals. Strip sheathing is common in sheds and barns which do not need insulation under the sheathing. Lay roofing paper over solid decking, and staple it in place. Fasten strip sheathing to rafters or trusses with 8d galvanized nails.
Set the first panel in place, and align it with the bottom and edge of the roof. Fasten it with galvanized screws with plastic washer caps, driven with a screw gun, into the second valley from the edge. Drive another screw into sheathing about a foot away, in a valley, to hold the panel. Add screws about every foot and into every strip. Use about 20 screws per panel. Do not put screws into the last valley on the inside edge.
Overlap the second panel by one ridge and one valley. Secure it with screws driven through that panel and the one below. Add other screws to secure the panel. Place other panels the same way until the roof is covered from side to side. Cut a panel in half lengthwise with tin snips to start a second row, if necessary, so seams will not overlap. Overlap a second row by at least 6 inches over the bottom row.
Cover both sides of the roof with corrugated panels. Secure the peak with special ridge caps, made to match the corrugations. Screw these in place on both sides of the roof. Add edge caps around the bottom and sides of the roof to prevent water from getting in under the corrugated metal; these typically slip under the corrugated panel and are secured with screws through the panel and the edge cap.