How To Figure An Existing Roof Slope

If you need to find the pitch of an existing roof all you need is a level and a tape measure.

How to figure an existing roof slope.

To measure the roof pitch you ll need an 18 or 24 inch level a tape measure and a pencil. This forms an angle of 18 5 between the horizontal section and the roof and creates a gentle incline that is seen as a midpoint between a low pitch and medium pitch roof. To do this simply convert the rise and run as a fraction to a decimal form eg. Then in the attic place the end of the level against the bottom of a roof rafter and hold it perfectly level.

First convert the pitch to a slope. First measure 12 inches from one end of the level and make a mark. To see how pitch impacts the look of a garage and changes cost click the design center button on our pole barn kits page. Working from the interior side of the roof you ll need access to a roof rafter to measure the pitch.

Roof pitch refers to the amount of rise a roof has compared to the horizontal measurement of the roof called the run. Locate the level s 12 inch mark. Here s an easy safe way to determine the pitch from inside your attic. Now you have to click the calculate button of the.

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. Now select the unit of measurement from the drop down. First of all you have to enter the value of the rise in the given place. Outside of the u s a degree angle is typically used.

This is very useful information for many purposes especially for roof framing the slope sometimes called pitch is calibrated on speed squares. Place the level horizontally along the rafter until it contacts the roof sheathing avoiding any protruding roof nails. Now select the unit of measurement from the. Right after you have to add the value of run in the given space.

For a simple gable roof the span wall to wall will be twice the size of the run wall to ridge horizontally. 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. 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. The slope is the same as the pitch.

Access one of the rafters then take the measurement this way. It is often compared to slope but is not exactly the same. For more complex roofs you may need to calculate it section by. Rise run rise run slope.

For a roof with the ridge above one wall the span is the same as the run. Use a level against the underside of the rafter you re measuring to get the most accurate value.