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  1. #1
    Join Date
    May 2018
    Location
    Greer, SC
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    2
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    Is This an Acceptable Installation Method

    Hello everyone.

    I am in the process of having a new 2 story home built (just getting started with the site prep). I was walking through a home in the same neighborhood that is the same floorplan as mine which is just about ready to have the sheetrock installed. This is a bit hard to explain but I will try. There is a section of the upstairs with a sloped ceiling that is sheetrock attached to the part of the rafter that is the slope of the roof. The builder has run a return air duct (flexible 12" insulated) through this space (about 5 feet long) in order to get from the first floor to the second floor attic where the air handles resides.

    This seem highly undesirable to me for two reasons:

    1. It seems like a LOT of heat will be transferred to the interior of the duct during the summer since this duct will be compressed into the space encompassed by the underside of the roof decking, second floor ceiling, and the roof joists.

    2. It seem like there is a high potential of the duct being punctured by the roofing nails that protrude through the roof decking into the space occupied by the duct. My assumption here is that since the 12" duct is being compressed into a rectangular space, the insulation will also be somewhat compressed thus the thickness of the insulation will be minimal and the (approx.) 1/2" of roofing nail sticking through the roof decking could easily reach and puncture the duct.

    So, is this a poor installation practice or is it okay and I should not be concerned. If a poor installation practice, how can I convince my builder that something should be done to improve this? I don't think there is another path for the duct available.

    Thanks,
    Bill

  2. #2
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
    Posts
    20,923
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    that's definitely hack work. maybe the roof line inside can be adjusted as to provide a deeper joist/truss space?

  3. #3
    Join Date
    Apr 2007
    Location
    Tucson, Arizona
    Posts
    1,169
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    Is This an Acceptable Installation Method

    In the past I’ve had to run the duct out of the roof in one area and back into the side of a higher section. The framers then come back and build a box 12” further away from all sides of this “doghouse” and the insulators pack R-30 on the sides and top. When we’ve had to do this, it’s only like a 24-36” cube up there. Maybe there’s a place that a doghouse would be a better fit than compressing the 12” flex between the roof deck and drywall, from your description it sounds like the insulation would be removed for the duct to occupy that space. Not the best way, my doghouse solution might not be the best way either, but it might be a better option.

    The inspector should be the one to point this discrepancy out to the builder, or the sub-contractor.
    There are two ways to do things, Right and Again.

  4. #4
    Join Date
    Jul 2006
    Location
    Prata di Pordenone
    Posts
    7,226
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    typical builder grade install. it all about the aesthetics till it gets hot .
    Go Trump

  5. #5
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    1,297
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    Waaaay too many times I've had to install 50 lbs of feces in a 5 lb box. Builders and Architects will never give you any room for equipment or ductwork and the lady of the house (multi-million $ McMansion) says "you are NOT going to put that THING on my roof! (vent terminations) Or you are NOT going to put that thing next to MY house! (condensing units) Or, you are NOT going to put THAT thing on my wall! (stat)

    Sigh.... So glad I am not in that gig anymore.

  6. Likes HVAC_Marc, beshvac liked this post
  7. #6
    Join Date
    May 2018
    Location
    Greer, SC
    Posts
    2
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    Thread Starter
    Ok, so this is not a good thing to do. Unfortunately, this is a production builder and making changes seems almost impossible. Is there something simple that can be done to at least improve the situation - like maybe install a 1/2" piece of foam board between the duct and the roof deck? This would alt least eliminate the issue with roof nails puncturing the duct. Any other ideas?

    I'd add a picture but I don't have enough posts yet.

  8. #7
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
    Posts
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    it's easy - put a stop work order on the builder. Tell everyone to go home until it's resolved. The duct wont work crushed and punctured.

  9. Likes kdean1 liked this post
  10. #8
    Join Date
    Feb 2013
    Location
    Sonora, California, United States
    Posts
    4,221
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    Or better yet put in a ductless mini split

    Sent from my SM-G955U using Tapatalk

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