Quick Answer: What is the roof slope factor?

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Written By Thurman Schinner

The roof slope factor is written as ?x/12,? where ?x? is the vertical distance you measured from roof to level. If the measurement was 8, then your roof slope factor is 8/12, and you have a conventional roof slope. The roof slope factor is a measurement of the vertical rise in inches over a 12-inch span.
What is roof factor?
What is a Roof Pitch Multiplier? A roof pitch multiplier, also called a roof pitch factor, is a number that you use to find the actual surface area of a pitched roof. You multiply the roof pitch multiplier by the area, or footprint, covered by a sloped roof to produce the actual surface area of the roof.
What is the standard roof slope?
Conventional slope roofs are most common with residential roofs. This means the slope has a pitch between 4/12 and 9/12 on most homes. Roofs with a pitch exceeding 9/12 are called steep slope roofs.

What is rafter factor?
For example, if your roof pitch is 30? and your run is 2.4m then reading from the table the rafter length factor is 1.15. Multiply this factor by your run which gives your rafter length. If you want to add on a rafter foot (overhang) add this to your rafter length.

What is a 12 12 slope?
In this pitch, the first twelve is your roof?s rise and the second twelve is the roof?s run. The roof?s incline increases 12 feet for every 12 feet of horizontal measurement.
What is a 4/12 roof slope?
A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a ?4 in 12? slope. The slope ratio represents a certain amount of vertical rise for every 12 inches of horizontal run. For example, a ?4 in 12? slope can be expressed as the ratio of 4:12. A ?6 in 12? slope is expressed as 6:12.
What pitch is a 30 degree roof?
A 30? roof pitch is roughly the same as a 7/12 roof pitch. To convert from degrees to the American ratio: Find the tangent of the angle, tan(angle). This gives you the pitch of the roof.
What pitch Should a roof be UK?
A typical roof pitch in the UK for a traditional house will be 40?-50? but at the extreme can go up to 70? (above 70? would actually be called a wall!) Part of the choice of pitch is down to the architect and different period homes will have different pitches which are more ?aesthetically pleasing? to the designer.

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