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  1. #1
    Join Date
    Oct 2014
    Location
    Minnesota
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    6

    Default Gable vent between attic separation

    I can't find anything on this condition. Half of the gable vent is visible at either side of the attic partition wall in a town home. Only thing I can find references interior penetrations of the separation wall itself. Defect?

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  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Gable vent between attic separation

    Townhouse separation wall splits at ridge and thus splits the gable vent ... If I understand you correctly.

    Big no - no!

    Basically makes the fire separation wall ineffective as it gives fire a path around the fire separation wall.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
    Join Date
    Oct 2014
    Location
    Minnesota
    Posts
    6

    Default Re: Gable vent between attic separation

    Makes perfect sense, I just can't find a specific code to cite. Do you know the specific code? This is for a physical needs analysis.


  4. #4
    Join Date
    Mar 2007
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    Fletcher, NC
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    Default Re: Gable vent between attic separation

    I didn't find a Minnesota code on the ICC code list, but this is from the 2012 IRC: (bold and underlining are mine) (the separation wall is most likely a common 1 hour rated wall, thus the Exception would be applicable)
    - R302.2 Townhouses. - - Each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls.
    - - - Exception: A common 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E 119 or UL 263 is permitted for townhouses if such walls do not contain plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be installed in accordance with Chapters 34 through 43. Penetrations of electrical outlet boxes shall be in accordance with Section R302.4.

    If there is a gable vent opening in the exterior walls, then the separation walls does not "extend to and be tight against" the exterior wall (there is no wall there, there is an opening there).

    - R302.1 Exterior walls.
    - - Construction, projections, openings and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1(1); or dwellings equipped throughout with an automatic sprinkler system installed in accordance with Section P2904 shall comply with Table R302.1(2).
    - - - Exceptions:
    - - - - 1. Walls, projections, openings or penetrations in walls perpendicular to the line used to determine the fire separation distance.
    - - - - 2. Walls of dwellings and accessory structures located on the same lot.
    - - - - 3. Detached tool sheds and storage sheds, playhouses and similar structures exempted from permits are not required to provide wall protection based on location on the lot. Projections beyond the exterior wall shall not extend over the lot line.
    - - - - 4. Detached garages accessory to a dwelling located within 2 feet (610 mm) of a lot line are permitted to have roof eave projections not exceeding 4 inches (102 mm).
    - - - - 5. Foundation vents installed in compliance with this code are permitted.


    You could use R302.1 Exception 1 ... except that there is no exterior wall at the opening, thus you would need to go to Table R302.1(1), and nothing in that table allows an opening to be in the exterior wall and span across the separation wall.

    What they should have done was to have installed two gable vents in the exterior walls, leaving an exterior wall between the two openings for the separation wall to meet to.

    Just too much wrong with that installation to cover it all here, but the above should help.

    Hopefully, there is no ridge vent at the ridge above where the separation wall is - I have seen that before too, also a big no-no.

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    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  5. #5
    Join Date
    Oct 2014
    Location
    Minnesota
    Posts
    6

    Default Re: Gable vent between attic separation

    Thank you! I appreciate it.


  6. #6
    Join Date
    Jun 2008
    Location
    Stacy, MN
    Posts
    148

    Default Re: Gable vent between attic separation

    Minnesota is still using the 2006 IRC; the 2012 IRC Goes into effect in on Jan. 24, 2015. The 2000 & 2006 IRC 302.1 Sections basically says the same thing as Jerry's quote. The local jurisdiction may have allowed it because the wall is perpendicular to the property line, not much different than a window on either side of the wall. I am not saying it is right, I don't know that would have approved it.


  7. #7
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Gable vent between attic separation

    Quote Originally Posted by Fred Weck View Post
    The local jurisdiction may have allowed it because the wall is perpendicular to the property line, not much different than a window on either side of the wall.
    That would be code complaint if ... ... If the opening did not span across the end of the separation wall.

    I suspect it just slipped by them - that they didn't catch it at plan review or at inspections.

    It may also be possible that the inspector noted that there was insufficient venting openings and told the contractor to install a gable vent on each side of the separation wall -and that aafter the inspector left the contractor told his workers to install a gable vent on each side of the separation wall, and when the workers asked how far from the separation wall the vent had to be - the contractor said to the effect of "It doesn't matter."

    And what is there is a result of the workers not understanding the code (few workers read, know, or understand code requirements).

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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