Draw a simple diagram of your roof. Divide it into sections. For example, a straight roof with no extra elevations or dormers would have fewer sections than a roof with multiple roof lines. Take this diagram with you onto the roof when you are ready to measure. (See Resource for sample diagram.)
Climb up on the roof and measure the width and length of each section in feet. Round up if necessary. Write down these numbers in the appropriate sections of your roof diagram.
Multiply the width and length to get the square footage of each section. Write the total square feet of each section on the diagram. Add all the square footage totals from each section together to determine your total square footage. Divide this number by 100 to find how many squares (one square = 100 square feet) of roofing material you will need.
Find out how many bundles of shingles equal one square for your particular choice of shingles, then place your order accordingly.
- Wear shoes with good traction when working on a roof. It is safer and easier to measure a roof if you have a helper there to write down the numbers for you.