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  1. #1
    Join Date
    Mar 2007
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    Daniel Island, SC.
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    230

    Default 2/12 slope for shingles

    Is it possible to have a 2/12 sloped roof shingled? If so, what is the criteria?

    Also what if they used a ice and water underlayment? Would that be acceptable with shingles if they decreased the exposure?

    The house is ocean front.

    Jim

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  2. #2
    Join Date
    Mar 2007
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    Ormond Beach, Florida
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    Default Re: 2/12 slope for shingles

    Quote Originally Posted by JIM MURPHY View Post
    Is it possible to have a 2/12 sloped roof shingled? If so, what is the criteria?
    Yes, some manufacturers allow down to a 2/12 slope as I recall. How? According to their installation instructions.

    I believe the underlayment is doubled over what is normally called for.

    Also what if they used a ice and water underlayment? Would that be acceptable with shingles if they decreased the exposure?
    Might work and might be acceptable, you would need to check the manufacturer's installation instructions.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3
    Join Date
    Mar 2007
    Location
    Knoxville, TN
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    Default Re: 2/12 slope for shingles

    2/12 is the minimum slope for shingles


  4. #4
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    Mar 2007
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    Ormond Beach, Florida
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    Default Re: 2/12 slope for shingles

    Quote Originally Posted by Jack Feldmann View Post
    2/12 is the minimum slope for shingles

    You sure?

    The ones I recall are 2-1/2 in 12 or 3 in 12, as I recall (although it has been a while since I have looked as I have not found shingles on that low of a slope in years.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
    Join Date
    Jun 2010
    Location
    West Chester PA
    Posts
    166

    Default Re: 2/12 slope for shingles

    A shingle installation on anything less than 4 / 12 in this area,
    I recommend a roofer review along with repairs to correct deficiencies.

    Snow loads the last couple of winters have been incredible.

    your mileage may vary.....


  6. #6
    Join Date
    Jun 2008
    Location
    Maryland
    Posts
    1,049

    Default Re: 2/12 slope for shingles

    Chapter 9 - Roof Assemblies

    IRC is the same language too.


  7. #7
    Join Date
    Mar 2007
    Location
    Chicago, IL
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    Default Re: 2/12 slope for shingles

    Typically, the manufacturer's installation instructions are going to recommend or require upgraded underlayment, and reference the appropriate ASTM standards.

    I tell clients "In my opinion, in our climate at 2/12 the shingles are a 'decorative roof covering', and it's the underlayment providing the water resistance".

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    Michael Thomas
    Paragon Property Services Inc., Chicago IL
    http://paragoninspects.com

  8. #8
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,546

    Default Re: 2/12 slope for shingles

    Quote Originally Posted by Michael Thomas View Post
    Typically, the manufacturer's installation instructions are going to recommend or require upgraded underlayment, and reference the appropriate ASTM standards.

    I tell clients "In my opinion, in our climate at 2/12 the shingles are a 'decorative roof covering', and it's the underlayment providing the water resistance".
    What about all the shingle nail holes in your nice underlayment?

    Nobody shingles a 2 in 12 in my area, the wild Wet Coast. It would leak. Period.
    A few years back, I saw a 3 in 12 shingled and I called it suspect. The shingle exposure should be reduced an inch or more for 3 in 12. Forget about anything like 2 in 12. That would need torch-on modified bitumen. At least, that is what they do here.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  9. #9
    Join Date
    Mar 2007
    Location
    Chicago, IL
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    2,797

    Default Re: 2/12 slope for shingles

    Quote Originally Posted by John Kogel View Post
    What about all the shingle nail holes in your nice underlayment?

    In my experience, here in Chicago properly self-adhesive WSU is sufficiently self-healing to work successfully under comp shingles installed at any slope allowed by the manufacturer.

    Which is not to say that I think such installations between 2/12 - 4/12 are a Good Idea, but only that 1) I personally have not seen them fail due to water intrusion through the underlayment and 2) I cannot fault them for violating the manufacturer's installation instructions.

    More often, I'm writing them up at HIs or WIs because the underlayment does not even meet the manufacturer's installation requirements or R905.3.3.1 and/or because of flashing or similar details - I should be so lucky as to find WSU!

    Michael Thomas
    Paragon Property Services Inc., Chicago IL
    http://paragoninspects.com

  10. #10
    Join Date
    Mar 2007
    Location
    Knoxville, TN
    Posts
    2,445

    Default Re: 2/12 slope for shingles

    Jerry,
    I'm pretty sure. I re-checked and R905.2.2 covers it.


  11. #11
    Join Date
    Oct 2011
    Location
    Minneapolis, MN
    Posts
    780

    Default Re: 2/12 slope for shingles

    Might wind be a concern on a ocean front house with such a low pitch?


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