How To Work Out Flat Roof Percentage

Pitch measurement method 1.

How to work out flat roof percentage.

Pitch rise run 1 5 6 25. On a ladder beside the roof place the level a foot or so up the roof hold it level and measure from the 12 inch mark on the level s bottom straight down to the roof. Calculate the roof pitch as the proportion of rise and run. 8 inches and you have an 8 in 12 pitch.

Use a level against the underside of the rafter you re measuring to get the most accurate value. I just want to check how this is calculated. Access one of the rafters then take the measurement this way. If this distance measures 4 inches you have a 4 in 12 pitch.

The most precise way to find the roof s slope is by measuring it from the underside. Hold the 0 mark of the tape measure against the roof. Calculate the rafter length substituting these values into the following formula. Move the tape measure along the the roof until it hits the level at exactly the 12 inch mark.

Here s what i did. Working on one of the previous example lets assume we have a slope that has a run of 10m with a rise of 500mm. Measure the vertical distance from roof to level. Measure the rise of your roof.

If you have any concerns as you are determining your flat roof snow load consult with a structural engineer or roofing specialist. Let s say it is equal to 1 5 m. How to work out slope percentage if we want to work out the percentage of a slope you first must ensure you convert the units so they are the same similar to working with the ratios above. Extend it upward so it is perpendicular to the level.

Locate the level s 12 inch mark. I ve checked the room dimensions up and down left and right and i can t get anywhere near the threshold but i m nervous.