For example a roof with a 6 inch 12 pitch is one where it rises 6 inches vertically for every 12 inches of the horizontal run.
Roof angle for snow.
It is determined based.
For lots more information on which roof finish to use for which slope and indicative costs.
In the roofing trade the go to term is pitch and it is expressed in terms of 12 inches so the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally.
According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.
If water does not properly run off of a roof it will begin to seep in causing rot interior damage and possibly dangerous black mold.
Intuitively this is the number of inches of snow on your roof in the place where the cover is the thickest.
For slopes below 20 degrees systems such as epdm fibreglass metal roofing can be used.
On multiple factors including.
In general determining the pitch of an existing roof is a simple calculation.
You can enter this value either as a ratio x 12 or as an angle whichever suits you better.
The requirements for an asphalt shingles roof are contained in the international building code.
If you re not sure which type to choose always settle for the wetter types as they are denser.
Importance occupancy and use of the building.
Roof snow load is defined as the weight of snow on the roof surface used in design of the building structure ibc 2012.
Pitch angle incline slope they all can be used to refer to the steepness of a roof.
In snowy areas your roof should be at least 10 12 40 to allow snow to shed while the safest roof pitch in very windy areas is between 4 12 6 12 18 5 26 5.
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.
Wind exposure of roof.
This image shows a shed with a roof pitch of 30 degrees with a covering of cedar shingles.
Visit the shed roofing page.
The purpose of pitching a roof is to enable water and snow to run off so the greater the amount of rain and or snow an area receives the greater the amount of pitch needed for the roof.