How To Figure Roof Pitch With Speed Square

Roof pitch is the measurement of a roof s vertical rise divided by its horizontal run.

How to figure roof pitch with speed square.

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. Divide the first part of the ratio by 12 to work out the pitch. Check your results with the omni roof pitch calculator. Marvel at your mathematical.

The triangle shaped square was invented in 1925 by albert swanson to provide a quick accurate method for marking rafters. To see how pitch impacts the look of a garage and changes cost click the design center button on our pole barn kits page. Find the inverse tangent of the pitch to find the angle in degrees. A speed square and level can be used to easily find the pitch of a roof.

It is often compared to slope but is not exactly the same. Often you express roof pitch as the ratio between the rise and the run in the form of x 12. Photo 2 shows how to use the speed square to mark a 33 1 2 degree angle the same as you would need on a rafter tail for a roof with an 8 12 pitch. You can assess this in two ways either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof.

Before miter saws and even since professional carpenters used speed squares as a quick saw guide for cutting 45 and 90 degree angles. In the united states a run of 12 inches 1 foot is used and pitch is measured as the rise of the roof over 12 inches. Because of its compact size it is frequently used as a saw guide when cutting framing members as well as a layout tool for quick 45 and 90 degree cuts. Finding the pitch of a roof is simple with a speed square.

To convert between american roofing ratios and pitch degrees follow these steps.