Formula To Find The Slope Of A Roof

For instance a 7 12 roof pitch means that the roof rises 7 inches for every 12 horizontal inches.

Formula to find the slope of a roof.

In the imperial unit of measurements the slope is expressed with the rise and run. Roof pitch degree table. You can also calculate roof pitch even without using a roof slope calculator. Rafter rise run from the pythagorean theorem.

Image 1 12 to 12 12 roof pitch 7 12 pitch. The overhang of a rafter at the end of the roof. How to calculate roof pitch. 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.

Place one end of a carpenter s level against the underside of the. Some of the frequently used roof slopes are. Measuring from the underside of the roof is usually the most accurate way to find the slope since there is no roofing material to make an uneven surface. This is very useful information for many purposes especially for roof framing the slope sometimes called pitch is calibrated on speed squares.

In the united states a run of 12 inches 1 foot is used and pitch is measured as the rise of the roof over 12 inches. In civil engineering the slope is the numerical measure of the steepness of a roof. Roof slope is also called as roof pitch. Generally roof pitch is calculated from the same formula that describes a right triangle.

Step 1 access a rafter. Rafter rise run this formula is from the pythagorean theorem. Tan 45o 1 00. Outside of the u s a degree angle is typically used.

Rise run pitch where pitch is expressed in percent. Here are the equations you may use to solve for the length of the slope and the rafter. The slope of the roof is determined by the vertical rise in inches for every horizontal 12 inch length or run a common formula is. Any of the following will give you a good measurement 1 x research source a rafter in the attic.

Slope measures the angle of change in elevation which can be obtained by dividing rise by run and multiply the result with 100. A barge rafter at the side of the gable step 2 position a level against the underside of the rafter. As a sanity check we confirm that the tangent of 45 degrees is 1 or that two opposed 45 degree or 12 in 12 slope roof surfaces will form a 90 degree angle where they meet at the ridge and will form 45 degree angles where they meet the wall top plate or with respect to any horizontal line in the building. This means that for ever 12 inches horizontally the roof rises x number of inches.

You can use the following equations to find the length of the rafter and the slope. It is often compared to slope but is not exactly the same. Slope the slope of a roof is represented as x 12 where x is the number of inches in rise for every 12 inches of run. By slope angle formula steepness can be obtained by dividing vertical rise by horizontal span.