How to Measure a Roof's Measurements

Keep a tape measure on hand when measuring a roof.

When measuring a roof, you'll need to determine both the square footage and the pitch. These measurements will come in handy when redoing a roof's shingles and sheathing. You'll need to know the roof's square footage when purchasing materials, such as shingles, to cover it. The pitch measurement will let you know how steep the roof is. The higher the measurement numbers, the steeper the pitch. To determine a pitch, measure out 12 inches from the roof.

Things You'll Need

• Tape measure
• 4-foot level
• Builder's square
• Pencil

Instructions

Square Footage

1. Stretch a tape measure from the roof's peak down to its eave to determine the width.

2. Measure from one end of the roof to the opposite end using the tape measure to find the length.

3. Multiply the roof's width and length to determine the square footage of that particular area.

4. Repeat this measuring process on the opposite side of the roof and on any separate gables.

5. Add all of roof's individual square footage measurements together to determine its total square footage.

Pitch

1. Set the end of a 4-foot level on the roof. Adjust the level until the bubble is centered between the two lines, which will mean it is plum.

2. Place a builder's square's 24-inch long blade on the roof. Slide the blade up the pitch of the roof until the square's 16-inch tongue is resting against the 4-foot level.

3. Check the level again to be sure it is plum. Next, make sure that the builder's square tongue is flush against the edge. Hold the two tools together with one hand and place a mark where the builder's square's bottom edge meets the level.

4. Measure the distance between the space where the level touched the roof to the mark that you made on the level. Divide the distance by two to determine the pitch. You'll divide the measurement by two as a roof's pitch scale goes up to 12 inches and a builder's square blade is 24 inches.

5. Write the number down with a 12 forward slash (12/) followed by the height number to represent the pitch of the roof.

Tips & Warnings

• If you use a ladder to reach the roof, have someone help by holding the base for added safety.

References

• Carpentry-Pro-Framer: Determining Roof Pitch
• "Carpentry"; Leonard Koel; 2004
• RoofHelp.com: Measuring Your Roof