To determine the minimum pitch of a roof, look at the existing roof or the material the roof is made of. Alternatively, consider the type of environment the roof is in to determine the minimum pitch of a new roof.
The easiest way to determine the minimum pitch of a new roof is to take a look at the old roof, as the pitch is likely to match the home. Buildings that have a number of roof pitches may not look cohesive, and all roofs should look as if they are part of the home.
Another way to determine the minimum pitch for a roof is to base the slope on the roofing material. For instance, the minimum pitch for a shingles roof is 1:6, but the minimum pitch for a metal roof is 1:4. If using roll roofing, the minimum pitch is 2:12.
Looking at the environment can also help to determine the minimum pitch of a roof. A home that is located in a region that gets a lot of snow should have a steep pitch of about 12:12 to allow the snow to fall off, but the minimum is a pitch of 2:12. If a roof is located in an area with a lot of trees, a minimum pitch of at least 2:12 is needed in order to allow debris and leaves to fall to the ground.