What is the minimum Pitch/Slope of an Asphalt Shingle Roof?
Shingles of all types need to have a slope to function properly. The minimum requirement is 2/12. The 2/12 number is rise over run or two units of vertical for every 12 units horizontal. That works out to about nine degrees if that works better for you. A shingle roof, like this North Dallas garage in the photo above, may have a failure, no matter how good a job the installer did. This minimum slope requirement can be found in the installation instructions for almost every manufacturer and in many building codes.
Normal Roof Slope for Typical Installation
Normal shingle installation is allowed for all roofs with a pitch of 4/12 and above.
Low Sloped Roof Shingle Installation
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? We do install shingles on these in between pitches but special application measures must be taken in this middle ground. You are required to have a double layer of asphalt saturated felt paper or a single layer of ice & water shield under your shingles. A word of caution: if you have a roof that is just above the minimum pitch, you still may better off using a different product than shingles.
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