Run And Rise Roof

Calculate the roof rise using the figures for unit rise and total run.

Run and rise roof.

The rise is the distance from the top of the roof to the bottom. It can be assessed in two ways either as the angle the rafter makes with the horizontal or the proportion between the rise and the run of the roof. The slope is the steepness of your roof and is the ratio between any two points on your roof. 3 of rise per 12 of run is the same as 1 of rise per 4 of run or 1 4 25.

Rise and run for your porch roof your roof s slope also called pitch is determined by the rise and run. Roof pitch is simply the slopecreated by the rafter. Why is the roof slope 25. Pitch is the incline of the roof represented as the ratio of rise to the span twice the run.

Using the example it would be six inches times 13 feet. Roof pitch is often expressed as a ratio between rise and run in the form of x 12. Multiply your figure for unit rise by your figure for total run to get the total rise. The total run is the distance from the peak to the edge of the roof which in this case is the total width divided in half which is equal to 10 feet or 120 inches.

The following table shows the roof pitch rise in run equivalents for all roof slopes in degrees from 1 to 72. A 3 in 12 roof rises 3 for every 12 of run. The run is the distance from the outside of the wall to the inside of the ridge. For example if the roof rises 4 feet and the span is 16 feet twice the run then the pitch is 4 16 or 1 4.

The total roof rise in the example equals 78 inches. Total roof rise or change in elevation for a 38 degree sloping roof angle t with one giant rise or step of 7 8 feet to the center of the attic y 2 would have total a run x 2 of 10 feet. A roof pitch that is based on a fixed rise and run and does not end up with a whole number is known as a bastard pitch. It just means the top of the roof has to end out at a specific place.

That s the same as a 14 degree slope or a 25 slope. Here is an online rise and run calculator which helps to calculate pitch slope and angle with the help of rise and run values. This is rarely is a whole number it is not a rare event and it is not a nightmare. Other than the 45 roof slope which is 12 in 12 none of the standard roof pitches 5 in 12 6 in 12 etc are equal to a whole degree.

The horizontal change in distance or the horizontal distance covered by an un supported rafter or truss. Enter the rise and run for the pitch length and angle of the rafter.