Speed Square Roof Pitch

The triangle shaped square was invented in 1925 by albert swanson to provide a quick accurate method for marking rafters.

Speed square roof pitch.

And it can be used to mark any angle between 0 and 90 degrees across a board s face. Therefore if your roof rises 4 inches over the course of 12 inches of horizontal run then your roof pitch is 4 12. It can be used to make lines perpendicular square to a board s edge. 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.

48 10 4 8. There are many other ways the speed square can be used but i will focus on these two in this tutorial. Constructing a new shed roof at the desired pitch is as easy as knowing how to use a speed square. The calculator above can handle much of this math.

Then place a torpedo level on the fat base of the rafter square and adjust the square until the level is level and read the pitch on the side of the rafter square. Now divide the rise by the multiplier to get the pitch eg. You can use the speed square to mark an angle such as when cutting a rafter tail by holding the pivot point against the board. To find the pitch just place the pivot point against the shingles.

You can also use a speed square to find level if you re on the job without a spirit level. You can use a speed square to find pitches. Since pitch is the rise over a 12 inch run divide the run by 12 to get the multiplier in this case 120 12 10. As stated in the video speed squares have useful markings on them from 0 to 12.

A speed square will have two specialty protractor angle guides on the inside of the tool which has both common rafter angles and hip valley angles marked out. The swanson speed square is a popular tool with most carpenters. You have a perfect 45 degree angle for easy corners. The pitch of this roof is 4 8 12.

The best rating speed is quite expensive which quickly begins to get any roof. So the common roof square is measured by the textbook guidance above the protractor. The key is a protractor function that identifies the common and rare roof pitches. Swing the square until you read the desired angle on the board s edge and make your mark.

Common roof pitches set as grow inches over a twelve inch run.