To express a slope of 1 3 as a roof pitch you would multiply by 4 4 to produce 12 in the denominator of the ratio.
Roof slope 3 12.
This will give you the rise over run or pitch.
The ratio can be indicated by a division slash separating the numbers such as 2 12 or 7 12.
A roof slope of 7 12 is also good and can provide the additional benefit of helping minimize the effects of wind driven rain.
Roof slopes are most commonly defined by the rise over run ratio.
Roof pitch is a term describing how steep or flat your roof slope is.
The fraction 4 4 equals 1 so it doesn t change the value of the pitch and it produces a pitch of 4 12.
Roof pitch defined and explained.
A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof.
Roof pitch designations are comprised of two numbers indicating a ratio.
I e 4 inches of rise per 12 inches one foot of run.
Roof pitch degree table.
Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof.
Roofers like to express the roof pitch ratio in inches and for simplicity they always use a run of 12 inches.
Most roof s have a pitch in the 4 12 to 9 12 range.
What exactly is roof slope.
However from the wind uplift mitigation perspective a 7 12 roof slope can be considered as a two story building due to the higher overall steepness and profile of the roof.
Pitch is the term used to describe the angle slope or slant of your roof.
Image 1 12 to 12 12 roof pitch 7 12 pitch.
We included a roof pitch chart below the 7 12 example image and the calculator below that.
For example if you measure 4 inches the pitch of your roof is 4 12.
Simply locate a roof rafter board place the end of the level against the bottom edge and measure from the 12 inch mark vertically to the bottom edge of the rafter.
If a roof rises 3 in a length of 12 this is 3 12 roof pitch.
Or the colon can replace the slash as in 2 12 or 7 12.
The table below shows common roof pitches and the equivalent grade degrees and radians for each.
If this isn t practical then perform the same measurement on the underside of the roof.
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.