How to Replace a Corrugated Roof

Remove the old roof panels. Get on a ladder and use a pry bar and hammer or a screw gun to remove the nails or screws holding roofing to the roof framing. Start at the top and remove one panel at a time. Wear gloves to protect against cuts from sharp edges or tears in the metal. Drop the panels off the roof to the ground for disposal.

Inspect the roof decking; on older buildings it often is solid wood of some sort, although "strip" sheathing of 1-by-4-inch boards nailed across rafters is also used frequently. Make sure the decking is not rotted or damaged in any way and is solid enough to support the new panels. Replace any damaged decking and replace strip sheathing with solid decking.

Lay roofing paper or other waterproof membrane over the decking. Fasten it with a construction stapler. Place paper horizontally on the roof, from end to end, starting at the bottom and overlapping layers by about 6 inches from the top.

Set the first new corrugated panel in place at the bottom of one end of the roof. Fasten it to the decking with galvanized or aluminum screws, to match the roofing, with plastic washer caps to seal the screw heads. Drive screws in with a screw gun in the corrugation valleys. Put the first screw one corrugation in from the edge of the roof.

Fasten panels from one end of the roof to the other, overlapping by one ridge and one valley at joints. Put screws through both panels at seams. Allow a slight overhang at both the end and bottom edge of the roof. Add panels the length of the roof and use tin snips to cut the last panel to fit if necessary; make any cut to the inside of the roof where it overlaps another panel.

Start a second row of panels, if necessary, by cutting a panel in half lengthwise, so the joints of the panels do not align. Cover both sides of the roof with new corrugated panels. Install cap plates, formed to match the corrugations, at the peak of the roof, to overlap panels on both sides. Place filler strips or edge caps along the sides and bottom of the roof; some corrugated metal uses caps which overlap the edge of the roofing, others use filler strips, which seal the gap between the panel and the decking.