How To Measure Roof Pitch With A Speed Square

With a torpedo level and a speed square you can pretty accurately gauge the pitch of any roof with a gable end photo 1.

How to measure roof pitch with a speed square.

If it s four inches you have a 4 in 12 pitch and so forth for other measurements thereby determining your roof pitch. Placing a ladder near the roof you will put a level a foot or so up on the roof hold it level and measure from the 12 inch mark straight down. If you need to find the pitch of an existing roof all you need is a level and a tape measure. This is simply 100 square feet of roof.

Let s assume it is equal to 6 m. To find the squares divide the overall roof area by 100 and then round up. Measure the rise of your roof. A distance of 7 inches 18 cm for example would mean your roof has a pitch of 7 in 12.

A 14 in 36 cm difference for example indicates a pitch of 7 in 18 cm. 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. Let s say it is equal to 1 5 m. 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. Place the level horizontally along the rafter until it contacts the roof sheathing avoiding any protruding roof nails. Use a level and a pencil to make a plumb vertical line on one face of an existing rafter. Measure with a speed square a speed square and level can be used to easily find the pitch of a roof.

If you re using a 2 ft 0 61 m level divide the distance between the level and the roof by 2 to get the true pitch. Measure the run length it is the horizontal distance between the roof ridge and the wall of the building. For instance if the roof is 1550 square feet then it is 16 squares. 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.

Working from the interior side of the roof you ll need access to a roof rafter to measure the pitch.