How Tofind Slope On A Roof

Roof slopes are measured in units of twelves.

How tofind slope on a roof.

To find the angle of a roof in degrees convert the pitch to a slope then convert to degrees by finding the arc tangent of the slope. Mark the length with the marker. Measure 12 inches on a carpenter s level. If you do know the roof slope in degrees then all you have to do is find the secant using a scientific calculator.

Measuring slope from the roof surface 1. Rise run rise run slope. Access one of the rafters then take. Climb up a ladder without your tools to take a look at the roof surface.

How do you calculate the slope of a roof. For example if the roof slope angle is 45 then sec 45 1 414213. To do this simply convert the rise and run as a fraction to a decimal form eg. The most precise way to find the roof s slope is by measuring it from the underside.

The slope of a roof often referred to as the pitch is determined by rise over run the roof s vertical rise in inches for every twelve inches of horizontal length the run. So a roof with four inches of rise every 12 inches horizontally run would have a slope of 4 12 sometimes displayed as 4 12. To find the slope in degrees you divide the rise by the run and find the inverse tangent of the result. The minimum roof pitch for shedding snow is around 30 or a 6 12 or 7 12 slope although this is not a definite as the material of your roof the direction of the snow and wind are some factors that can affect whether or not snow will slide as roofs of as little as 10 have been reported to shed snow.

The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. For example when a roof has a slope of 5 12 the roof is 5 inches high for every 12 inches long. Use a level against the underside of the rafter you re measuring to get the most accurate value. But you still need to have the rise and the run to find the degree angle if you don t already know it.

This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. How to convert roof pitch to degrees. Many levels are equipped with a ruler on. Locate the level s 12 inch mark.

Figuring this is simple. You can measure with twelve feet or twelve yards but in this article we will use twelve inches.