pex lines run in 2x6 wall between garage and living space

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by burhead, Apr 11, 2013.

  1. burhead

    burhead New Member

    Messages:
    2
    Location:
    Iowa
    I recently added a new garage with living space above it. To get plumbing to the new upstairs I had to go through a newly constructed 2x6 wall that separates the garage from the house. The lines are wiresbo pex and run in the center of the 2x6 so there is about 2.5" on either side of the line. They run through about 30' of wall and transition up into the ceiling of the garage. The ceiling of the garage is 16" TGIs and will be filled with celulose so there is little chance of freezing up there. The area above the garage is conditioned living space. My major concern is pipe installed in the 2x6 wall cavity. The garage is setup for radiant heat but that may not get done by next winter so I want to set this up to work under those conditions. I am thinking of using standard fiberglass insulation and also installing the foil (bubble wrap) on the cold side of the wall as extra insulation. Another thought was to put the split foam on the pipes in addition to the fiberglass insulation. The garage itself will be well insulated but our temps dip to 0F at times in the winter so it could be possible that the garage itself may see freezing temps. Any input is greatly appreciated.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    You want the pipes to be next to the heated wall with insulation between them and the garage wall. Adding insulation between the heated wall surface and the pipe means it won't get heat from the house...insulation doesn't make heat, it just slows the transfer, and you need it between the pipe and the cold side. Maybe some foam panels on the garage side. You could add a second layer with a slot for the pipe, open to the house side. Keep in mind, on the garage side, it needs to be fire-rated drywall...typically 5/8" thick to meet code.
  3. burhead

    burhead New Member

    Messages:
    2
    Location:
    Iowa
    Ok that makes sense. I was going to use the batts with paper on one side. Typically it would be installed with the paper towards the inside. I wonder if there would be a problem reversing the insulation so that the paper was on the garage side. I know this would put the vapor barrier on the wrong side but it would keep the pipes more towards the warm side.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    In your climate, I think the vapor barrier must be towards the inhabited side. There are climates where it works better on the outside, but I think Iowa gets too cold. Foam can be upwards of 5/inch where fiberglass is lucky to get to R1-2 or so.
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