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

The hash marks with corresponding numbers between 1 and 30 refer to the roof s rise angle.

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

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. Step 3 note the number on the common scale parallel with the 45 degree angle of the square. Place the pivot point against the shingles. At the corner of the square there is a pivot point.

Align the lip of the rafter angle square along the plumb line. Step 2 find an angle. Follow the bottom edge of the rafter to where it meets the common pitch reading. 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.

Because the speed square is a 90 degree angle each line on the diagonal represents one degree for a total of 90. Line up the pivot point on the bottom edge of the rafter. This is called the plumb line. Hold the pivot point against the board and move the square until your desired angle lines up with the edge of the board.

As an example pivot the speed square until the numeral 30 aligns with the opposite edge of the piece of material. It s often marked right on the tool. Draw a line down the pivot point edge of the speed square on the exact same side that the 90 degree line was drawn. If not the 0 degree mark should be at the opposite.

The pivot is a point at one end of the lip about which you can rotate the speed square to find angles. Then place a torpedo level on the fat base of the rafter square and adjust the square until the level is level. With a torpedo level and a speed square you can pretty accurately gauge the pitch of any roof with a gable end photo 1. Use a spirit level to mark a straight vertical line across the rafter.