METAL ROOFING? How to Install Measure the area Before you can begin to update your roof, you will have to get an accurate measurement and order your materials. Get your materials You will most likely have to order the roofing metal in the amount and color specific to your houses. Prepare a work site In order to make your installation as easy as possible, it is important to have a well-organized work area. Remove the old roofing Although you can install corrugated metal roofing over shingles, for the best foundation it is recommended that all the old roofing be removed. Repair any damage With the old materials removed, the bare bones of the roof frame or plywood sheathing will be exposed. If there is any damage to the sheathing, insulation, or ventilation, fix it now. Add your insulation layer This helps to block out moisture from getting trapped between the metal roof and the sheathing..