How to Estimate Roofing Materials
- 1). Climb onto your roof with your tape measure. Take one measurement from the top of the main part of the roof to the eaves, and another from end to end. Multiply the two measurements to get square footage (i.e., a roof section 40 feet long by 20 feet high is 800 square feet).
- 2). Repeat the process for each section of your roof. For areas that aren't square or rectangular, use the longest span to incorporate into your calculations.
- 3). Once you have the total square footage, add 10 percent. So for a roof with a total combined square footage of 2,000 square feet, your working number will be 2,200.
- 4). Divide that number by 100 to get the number of roofing squares you need. In this example, you would order 22 squares of roofing shingles.
- 5). Order your felt underlayment for the roof using the same figure of roofing squares. Calculate the number of roofing nails you need by multiplying the number of roofing squares by 350, which is generally how many nails you'll use for each roofing square.
