How Tofind Slope On A Roof

Measure 12 inches on a carpenter s level.

How tofind slope on a roof.

To do this simply convert the rise and run as a fraction to a decimal form eg. 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. Figuring this is simple. For example when a roof has a slope of 5 12 the roof is 5 inches high for every 12 inches long.

For example if the roof slope angle is 45 then sec 45 1 414213. 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. To find the slope in degrees you divide the rise by the run and find the inverse tangent of the result. The most precise way to find the roof s slope is by measuring it from the underside.

But you still need to have the rise and the run to find the degree angle if you don t already know it. 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. Access one of the rafters then take. 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.

Measuring slope from the roof surface 1. You can measure with twelve feet or twelve yards but in this article we will use twelve inches. Roof slopes are measured in units of twelves. Rise run rise run slope.

Mark the length with the marker. Climb up a ladder without your tools to take a look at the roof surface. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. Use a level against the underside of the rafter you re measuring to get the most accurate value.

If you do know the roof slope in degrees then all you have to do is find the secant using a scientific calculator. Confirm the roof is safe to walk on. Another way of stating this is that the roof has a rise of 5 and a run of 12. How do you calculate the slope of 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. Many levels are equipped with a ruler on.