The standard of lower pitch actually ranges between 1 12 to 5 12.
Minimum pitch of roof for snow.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
Intuitively this is the number of inches of snow on your roof in the place where the cover is the thickest.
Anything above that will require you to put out higher cost because they are already considered as higher pitch.
The pitch of the roof is determined by the vertical rise in inches for every horizontal twelve inch length.
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.
You can enter this value either as a ratio x 12 or as an angle whichever suits you better.
If your roof is pitched enter the length and width of the flat area covered by the roof.
But since there is still a wide variety of slate roofing systems there are occasions when the minimum pitch can go down to as low as 15 0 depending on the uniqueness of the roof.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
The minimum pitch is typically 3 12 meaning the roof should rise 3 inches for every 12 inches of horizontal foot.
The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
What is the smallest pitch of a roof.
This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally.
However you can only use this pitch with built up roofing or specialized synthetic roofing.
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.
In general determining the pitch of an existing roof is a simple calculation.
Any pitch higher than 9 12 is considered a steep pitch.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
A flat roof would have a 2 12 pitch while the average roof pitch would be between 4 12 and 9 12.
The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run.