How To Find The Pitch Of A Roof Using A Speed Square

Find the unit rise say inches per foot of the roof on the top line in the framing square rafter table e g.

How to find the pitch of a roof using a speed square.

Finding the pitch of a roof is simple with a speed square. You can use a speed square to find pitches. The triangle shaped square was invented in 1925 by albert swanson to provide a quick accurate method for marking rafters. Using a speed square as a try square the 90 degree right angle leading out from the pivot and the lip makes quickly and accurately finding right angles a no brainer.

As a matter of fact finding the pitch of a roof was the motivating factor for how this tool was invented in the first place hence it s official name the rafter square. Simply move the pivot point against the edge of your board lining up the edge of the board with your desired angle. As aforementioned there is no standard pitch of a roof. A speed square and level can be used to easily find the pitch of a roof.

To find the pitch just place the pivot point against the shingles. Set the level on the edge of the speed square as shown below then place the heel of the speed square on a rafter or gable edge of the roof. Express roof pitch as the ratio of the amount of the vertical rise of a roof or rise over the corresponding horizontal distance or run you write the pitch assuming a run of 12 inches thus the ratio would describe how much a roof rises for each foot of the run. A 6 inch rise per foot.

Read this number along the inches scale at the top of the framing square.