Measuring the amount of metal roofing you need is accomplished in various ways, depending upon the style of your roof. For example, if your roof has valleys and dormers, that will change the way you measure it. Here we describe a basic measure for a ranch-style home.
Measure the length of your roof. This is done by measuring from one outside edge of your roof to the opposite outside edge. For example, let's say you measure 30 feet (360 inches). Write this number down for the next step.
Determine the width of the metal you are installing. For example, standing seam metal roofing is 24 inches wide. Corrugated metal is 36 inches wide. Divide the length of your roof by the width of the metal. In our example we will use 24-inch standing seam roofing, so we will divide 360 inches by 24, which equals 15. This is the number of metal panels needed for one side of the roof.
Repeat Step 2 for the other side of your roof. It is important to measure both sides. Some older homes could have shifted slightly over the years. Measurements for the two sides could be different on these homes.
Determine the length of the metal panels needed for one side of your roof by measuring from the fascia board (the board attached to your roof joists) to the ridge (the peak) of the roof. For example, your roof could measure 12 feet to its peak. This number will tell you the total length of metal panels needed. Add an inch or two, depending on your preference for overhang. For example, if you measure 12 feet, then make the length 12 feet, 1 inch or 12 feet, 2 inches. Always measure in the middle of your roof and on each end, checking that the measurements are the same. In our example, we will need 15 panels, each 12 feet (plus an inch or two) in length, for one side of the roof. We will need a similar amount for the other side, based on its measurements.