How to Construct a Metal Shed Roof

Determine the width coverage area of the panels you plan to use; a 38-inch wide panel, for instance, will have a 36-inch coverage area, to allow for overlapping at seams. Measure the shed roof with a tape measure to determine the number of panels needed, based on the width coverage and length of the shed, and the length of panels from shed wall to peak. Panels come in varying lengths, from 6 to 12 feet; get a size so you only need one row to cover from wall to peak, if possible.

Install the first panel at the bottom of one edge of the roof, preferably facing away from any prevailing wind, with corrugations running down from the peak. Secure it with galvanized screws with plastic washer caps which seal the screw hole. Drive screws with a screw gun on every sheathing strip, in the valleys of the sheet. Make sure the panel edges align with the bottom and end of the roof. Allow some overhang of a couple of inches at the bottom. Cut an end panel with tin snips if required to fit the roof width.

Overlap the second panel according to the manufacturer's recommendation, typically one valley and one ridge. Put the first row of screws in the second panel through both sheets. Work to the other end of the roof. Start a second row of panels, if one will not cover to the peak, according to the manufacturer's directions; typically, the first panel on the second row will be cut in half lengthwise with tin snips so the vertical seams do not align.

Install ridge and edge caps over the peak and along the sides of the roof once all panels are in place. Follow the manufacturer's recommendation on these as styles will vary, but make sure the peak is sealed and edges are covered so moisture can't get under the corrugated sheets at the edges.