Minimum Slope Shingle Roof

What is the minimum slope for a shingle Roof ?

Shingles of all types need to have 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 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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Posted in Buying Tips, Educational
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7 comments on “Minimum Slope Shingle Roof
  1. john says:

    my small out house roof slopes from its high point of 8 feet, to 7 feet 4 inc at its lowest point at the gutter end, so it has a 8 inch drop is this enough to use shingle on it? regards John

  2. dallasbear says:

    Not enough information and really beyond the scope of a blog to answer specific questions. I suggest a pitch meter.

    That said, eight inches of fall is not much. It would have to be a tiny structure for that to be enough slope.

  3. Issac W Harper says:

    what is the iPhone app used in determine roof pitch used in an article:Home › Buying Tips › Minimum Slope Shingle Roof
    Minimum Slope Shingle Roof
    Posted on April 21, 2013 by dallasbear — 2 Comments ↓
    What is the minimum slope for a shingle Roof ?

  4. Joseph says:

    This is exactly why folks should always use a licensed roofing contractor! The every day person wouldn’t think twice about this, along with other specs.

  5. Greysean says:

    I had a flat room and the roofer installed a shingled roof – the pitch is between 2-1/2. They said they installed the ice and water membrane yet in a heavy rain water pours off the valley of the roof above and water leaks into my kitchen. They are saying it can’t be the roof. Any thoughts, this was put in less than 2 years ago.

    • dallasbear says:

      If the pitch is less than 2/12 shingles are not allowed by building code. They can leak even with ice & water shield.

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