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.

Step 2 find an angle. Use a spirit level to mark a straight vertical line across the rafter. Read the pitch on the side of 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.

With a torpedo level and a speed square you can pretty accurately gauge the pitch of any roof with a gable end photo 1. 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. Because the speed square is a 90 degree angle each line on the diagonal represents one degree for a total of 90. Hold the pivot point against the board and move the square until your desired angle lines up with the edge of the board.

Align the lip of the rafter angle square along the plumb line. The pivot is a point at one end of the lip about which you can rotate the speed square to find angles. Line up the pivot point on the bottom edge of the rafter. This is called the plumb line.

As an example pivot the speed square until the numeral 30 aligns with the opposite edge of the piece of material. Step 3 note the number on the common scale parallel with the 45 degree angle of the square. The hash marks with corresponding numbers between 1 and 30 refer to the roof s rise angle. Follow the bottom edge of the rafter to where it meets the common pitch reading.

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. It s often marked right on the tool. Now that the square has been lined up on the 30 degree mark however the angle drawn will be a 30 degree angle. If not the 0 degree mark should be at the opposite.