How To Use A Speed Square For Roof Pitch

Use the markings on the square to see where the roof edge lines up with the pitch notations.

How to use a speed square for roof pitch. 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. Simply move the pivot point against the edge of your board lining up the edge of the board with your desired angle. You have a perfect 45 degree angle for easy corners. This is accomplished by use of the main protractor and two specialty protractor angle guides on the inside of the tool.

To find the pitch just place the pivot point against the shingles. 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. You can use a speed square to find pitches. 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.

Simply brace the lipped side of the speed square against the edge of your board pencil a line up the hypotenuse of the speed square and voilà. 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. Use a level and a pencil to make a plumb vertical line on one face of an existing rafter. 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.