First the proper tools are needed. These are a measuring tape, a chalk line with plenty of chalk, a good drill, a safe extension ladder and a good, sturdy step ladder, ½ pound of ¼ inch roofing nails, metal roofing screws, metal snips, and a cloth nail bag to hold the nails and screws.
Measure the roof’s height and add the desired overhang, generally two to four inches. Take accurate measurements keeping in mind the handy man’s mantra “measure twice, cut once.” Next measure the roof’s length and height on both sides to figure out how much metal edging is needed. Take these measurements to your roofing supply company. They will tell you how much to purchase. Remember that three to six inches of unblocked air flow is needed between layers.
Although it isn’t necessary to remove the old one before laying down a metal roof, it is best. Use a pitch fork, roofing shovel, or roofing pliers to remove old shingles . Then lay down 30 pound tar paper to serve as the base for the new roof. If there’s only one layer of shingles on the old one, lay down 1″x4″x building length pine wood boards screwed onto the old shingles. Apply edging once the metal roof is prepared.
Start placing the metal sheets running from top to bottom. Screw them into the wood slats, using a screw every two feet on both sides of the sheet. Each sheet should overlap the last. When you reach the edge cut the last metal sheet so it’s just past the edge of the roof.
When the sheets are applied to both sides of the roof, apply the metal trim along the edges at the sides of the roof. The trim also goes on the peak, first scoring it in the middle so it can be bent over the peak.
Of course these instructions are useful only for installing the standard type of tin barn roof seen in industrial buildings, garages and the like. Other types require different methods for installation. But those can be tackled equally as well by a do it yourself person who wants to install metal roofing.