How To Use Speed Square For Roof Pitch

Use a level and a pencil to make a plumb vertical line on one face of an existing rafter.

How to use speed square for roof pitch.

For the other 98 of the world using metric check out my new video on the metric speed square. Simply move the pivot point against the edge of your board lining up the edge of the board with your desired angle. This is accomplished by use of the main protractor and two specialty protractor angle guides on the inside of the tool. The pivot is a point at one end of the lip about which you can rotate the speed square to find angles.

If not the 0 degree mark should be at the opposite. 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. Measuring pitches part of the speed square s role as a protractor and its original mission as a tool is in quickly finding common and uncommon rafter angles for the pitches on roofs. Swing the square until you read the desired angle on the board s edge and make your mark.

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. Use the markings on the square to see where the roof edge lines up with the pitch notations. It s often marked right on the tool. 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.

Place the pivot point on the square against the bottom of the rafter and align the 90 degree angle side of the square with the pencil mark. If the shed is unfinished then simply prop the speed square against the roof framing such as the rafter and repeat the same method. To find the pitch just place the pivot point against the shingles.