(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 6 of 6

Thread: Supply (& DWV) lines in exterior walls

  1. #1
    DIY Senior Member DavidTu's Avatar
    Join Date
    Dec 2009
    Location
    Seattle, WA
    Posts
    229

    Default Supply (& DWV) lines in exterior walls

    Perhaps Terry is best one to answer this one as I'm in Seattle so he knows the weather.... I'm wondering if it is acceptable to run supply lines in an exterior wall? (We'd be able to insulate.) As none of the bath's interior walls are shared w/ the downstairs (large open kitchen area) my other choice would seem to be to run up to attic and back down. What's best?


    (For sure I'd have to run the drains down the exterior... I assume that is fine?)

  2. #2
    Master Plumber-Gas Fitter shacko's Avatar
    Join Date
    Jan 2006
    Location
    Rosedale, Md
    Posts
    561

    Default

    Quote Originally Posted by DavidTu View Post
    Perhaps Terry is best one to answer this one as I'm in Seattle so he knows the weather.... I'm wondering if it is acceptable to run supply lines in an exterior wall? (We'd be able to insulate.) As none of the bath's interior walls are shared w/ the downstairs (large open kitchen area) my other choice would seem to be to run up to attic and back down. What's best?


    (For sure I'd have to run the drains down the exterior... I assume that is fine?)
    The trouble with questions like this is all your answers have to be comfirmed by your local jurisdiction.

    A lot of areas will allow supply lines on exterior walls, but they require insulation on the outer wall and none on the pipe, the pipe has to be run as close a possible to the inner wall.

    Most attics are cold areas, not a good idea to run water pipe in there.

    Drains run on the exterior are usually not permitted, like I said you have to ask locally, sorry.

  3. #3
    DIY Senior Member DavidTu's Avatar
    Join Date
    Dec 2009
    Location
    Seattle, WA
    Posts
    229

    Default

    Quote Originally Posted by shacko View Post
    Drains run on the exterior are usually not permitted, like I said you have to ask locally, sorry.
    Does that mean you cannot have a fixture on the exterior wall (i.e. drop down wall to floor level) or that you cannot have a stack on the exterior wall? (or both!?)

    (No insulation on pipe so that inside air can warm it, right?)
    Last edited by DavidTu; 05-28-2010 at 05:47 PM.

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,201
    Blog Entries
    1

    Default

    In Seattle you can do it.

    Just don't insulate the pipe in the wall, make sure the blanket of insulation is on the outside.
    If you put pipe insulation around the pipe in an outside wall, it will freeze quicker.
    It needs to get warmth from the inside of the home.

    Running pipes in an attic
    Don't put any insulation around the pipes.
    Remove all insulation below the pipe, and lay fiberglass batts over them.
    Between the ceiling joists on either side, lay two more batts, keeping space open below the pipes.
    The heat from the home must be able to get to the pipes, and then you trap it.
    A pipe in an uninsulated attic will freeze otherwise.

    If you change the pipes, then PEX would be good.

    Example of pipes in an attic.
    Last edited by Terry; 05-29-2010 at 10:00 AM.

  5. #5
    DIY Senior Member DavidTu's Avatar
    Join Date
    Dec 2009
    Location
    Seattle, WA
    Posts
    229

    Default

    Quote Originally Posted by Terry View Post
    In Seattle you can do it.
    Double check: You mean you can do both, right? (i.e. DWV and/or supply lines in outside walls)

  6. #6
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,201
    Blog Entries
    1

    Default

    In Seattle it never gets that cold.
    Surrounded by water on both sides, the Salish Sea (Puget Sound) to the West and Lake Washington to the East.
    Seattle plumbing code allows waste, vents and water in exterior walls.

    As always, during a cold snap you should open doors on exterior cabinets to allow warm air to the exterior walls that have plumbing ( kitchen sinks are a biggie)

Similar Threads

  1. How to insulate the exterior walls under a 3 season room.
    By Rughead in forum Remodel Forum & Blog
    Replies: 10
    Last Post: 04-14-2010, 07:08 AM
  2. Basement insulation -- XPS on just exterior walls?
    By ironspider in forum Remodel Forum & Blog
    Replies: 7
    Last Post: 03-02-2010, 12:35 AM
  3. Fuel Oil Lines Exterior Specs NJ
    By rlbarkleyii in forum Boiler Forum
    Replies: 2
    Last Post: 08-08-2009, 05:36 AM
  4. water lines, exterior walls, winter cold...
    By doc5md in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 7
    Last Post: 05-06-2009, 05:20 PM
  5. Corner Shower on Exterior Walls
    By wvsamdog in forum Shower & bathtub Forum & Blog
    Replies: 1
    Last Post: 11-12-2005, 01:21 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •