How To Find The Angle Of A Roof With A Speed Square

Place the pivot point against the shingles.

How to find the angle of a roof with a speed square.

Line up the pivot point on the bottom edge of the rafter. 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. Holding the level and speed square level locate the measurement on the speed square where it meets the bottom edge of the rafter to find the angle of the roof in degrees. This is called the plumb line.

Follow the bottom edge of the rafter to where it meets the common pitch reading. The hash marks with corresponding numbers between 1 and 30 refer to the roof s rise angle. With a torpedo level and a speed square you can pretty accurately gauge the pitch of any roof with a gable end photo 1. Then place a torpedo level on the fat base of the rafter square and adjust the square until the level is level.

The pivot is a point at one end of the lip about which you can rotate the speed square to find angles. Align the lip of the rafter angle square along the plumb line. Step 3 note the number on the common scale parallel with the 45 degree angle of the square. Because the speed square is a 90 degree angle each line on the diagonal represents one degree for a total of 90.

Step 2 find an angle. It s often marked right on the tool. Use a spirit level to mark a straight vertical line across the rafter. Hold the pivot point against the board and move the square until your desired angle lines up with the edge of the board.

At the corner of the square there is a pivot point. Read the pitch on the side of the rafter square. Draw a line down the pivot point edge of the speed square on the exact same side that the 90 degree line was drawn. 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.