Layout the roof surface using a tape measure and chalk line. Measure off of the end of the roof 39 inches at the top and bottom of the roof and place a pencil mark. This measurement will account for a 40-inch wide sheet of metal and will allow the metal to overhange 1 inch past the rake end of the roof. Snap a chalk line from the bottom to the top of the roof to connect these marks. This line represents the left edge of the first sheet of metal.
Lay the first sheet of metal onto the roof, aligning the left edge with the chalk line. Allow the bottom of the metal to overhang 1 inch to match the rake end overhang. Install metal screws into the flat surface of the metal, spacing them 12 inches apart and beginning 2 inches from the bottom of the metal sheet. Do not place the screws into the raised ridges of the metal. This will damage the metal by bending the ridges. The metal screws are fitted with rubber washers that will seal off the holes caused by the screws. Install the subsequent sheets by aligning them with the previous sheet, allowing the sheets to overlap at the joint. These sheets are designed to overlap and interlock at the raised ridges by 2 inches off of the left or right edge.
Install the metal roof ridge cap onto the ridge of the roof after the metal has been installed on both sides of the roof. The ridge cap is manufactured in 10 foot sections and must be overlapped by 6 inches upon installation. Insert metal screws through the roof ridge cap and into the metal raised ridges every 12 inches. Do not insert the screws all the way into the plywood decking beneath the metal. This will bend the raised ridges and damage the metals waterproofing properties. Trim off any additional metal using metal snips.