How To Work Out Flat Roof Percentage

Access one of the rafters then take the measurement this way.

How to work out flat roof percentage.

Move the tape measure along the the roof until it hits the level at exactly the 12 inch mark. 8 inches and you have an 8 in 12 pitch. Hold the 0 mark of the tape measure against the roof. For ground snow loads greater than 20 pounds per square foot the roof load is equal to 70 of the product of the exposure thermal and importance factors the ground snow load and 20 pounds.

Extend it upward so it is perpendicular to the level. Rafter rise run 1 5 6 2 25 36 38 25rafter 38 25 6 18 m. 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. Measure the vertical distance from roof to level.

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. 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. A policy we wish to take out specifies that we can have a percentage of the roof as a flat roof at no more than 25. Let s say it is equal to 1 5 m.

Locate the level s 12 inch mark. Calculate the rafter length substituting these values into the following formula. Calculate the roof pitch as the proportion of rise and run. Pitch measurement method 1.

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 rise of your roof. Use a level against the underside of the rafter you re measuring to get the most accurate value. If this distance measures 4 inches you have a 4 in 12 pitch.

If you have any concerns as you are determining your flat roof snow load consult with a structural engineer or roofing specialist. The most precise way to find the roof s slope is by measuring it from the underside.