If you are adding an addition to your home or installing skylights knowing the existing pitch is important.
Minimum roof pitch for snow.
The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run.
You can safely measure the roof pitch from inside your attic with a level that is either 18 or 24 inches a tape measure and a pencil.
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.
Minimum roof pitch for shingles.
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.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
The minimum pitch is typically 3 12 meaning the roof should rise 3 inches for every 12 inches of horizontal foot.
However you can only use this pitch with built up roofing or specialized synthetic roofing.
Begin by measuring 12 inches on your level and marking it with a pencil.
Anything above that will require you to put out higher cost because they are already considered as higher pitch.
The standard of lower pitch actually ranges between 1 12 to 5 12.
With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 20 0 for slate roofs.