How to Figure Roof Pitch on a New Building

Calculating roof pitch is necessary before laying shingles.

The pitch of a new building's roof is a numerical measurement of its slant or steepness. The main reason for pitch for a roof is to help the redirection of rain, sleet and snow. Determining the pitch of a new roof is essential in the process of laying the shingles or slates for the roof. The pitch of a roof is obtained by dividing its vertical rise by the measured horizontal span. Put another way, pitch is the distance a roof rises vertically over a 12-inch horizontal distance.

Things You'll Need

• Ladder
• Square
• Level

Instructions

1. Place the ladder against the side of the new building and climb it to access the roof's vertical rise and down slope.

2. Set the framing square on the vertical rise with the tongue facing up.

3. Hold the level flush plumb against the roof and the square's tongue.

4. Shift the square so that the long ends meet the roof edge at the 12-inch mark, then level the square in the horizontal position. The rise is the vertical arm of the square and the run is the 12-inch measurement. A roof with the vertical measurement of 7, would have a pitch of 7/12.

References

• Carpentry Pro Framer: Determining Roof Pitch