Pitch is measured in inches of vertical rise of the roof over one foot 12 inches of horizontal run.
Lowest pitch shingle roof.
We do install shingles on these in between pitches but special application measures must be taken in this middle ground.
Manufacturers of asphalt shingles recommend a pitch of 4 12 or more but the absolute minimum pitch is 2 12.
So a 4 12 pitch roof rises 4 inches for every 12 inches of horizontal run.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
Metal roof shingles require a minimum roof pitch of 3 12 or greater.
Current as of august 2020 asphalt shingles are an effective roof covering material for sloped roofs that can be successfully used on slopes as low as 2 12.
Mineral surfaced roll roofing requires a minimum roof pitch of 1 12 or greater.
As in all construction work paying attention to the little details can make all the difference between a long lasting trouble free project and one that results in callbacks and early failure never a good option with a new england roof.
If 4 12 and above is normal and 2 12 is minimum what about properties with roofs in between the two such as a 3 12 pitched roof.
Installation on roof slopes below a 2 in 12 pitch is not recommended at all.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
As well a slope of 4 12 is most commonly considered the lowest slope for standard shingle installations.
Normal shingle installation is allowed for all roofs with a pitch of 4 12 and above.
The asphalt shingle manufactures recommend that you install asphalt shingles on a recommended minimum of 4 in 12 or greater however most manufactures will warrant their shingles down to a 2 in 12 pitch if the recommended installation method is used.
Slate and slate type shingles require a minimum roof pitch of 4 12 or greater.
The recommended minimum roof pitch for shingles is 2 12 or simply two units of vertical rise to every twelve units of horizontal span.
Wood shakes require a minimum roof pitch of 3 12 or greater.
Low sloped roof shingle installation.
Most manufacturer and industry recommendations require or at the very least recommend special underlayment or other considerations on roofs between 2 12 and 4 12.
In either case find a professional roofing contractor experienced with low slope roofs and these specific products.