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Thread: Why the attic?

  1. #1

    Default Why the attic?

    Hi all,

    The house I'm buying is a one story on a slab that currently has polybutylene pipes, so I know I'll eventually need to get that repiped. (I'll be watching it like a hawk in the meantime.)

    So my question is if when rerouting the main from under the slab, why would it need to go through the attic? Couldn't it just poke into the bottom of a wall and then just go where it needs to go from there? I guess I'm just a bit confused as to why the pipes would need to go all the way up to the attic just to come all the way back down to the toilet or wherever it actually needs to go.

    Also, I'm looking into the idea of PEX with a manifold. Where do people usually put the manifolds in slab houses? Up in the attic as well? Copper isn't out of the question, but I'm not sure how acidic the soil/water is here. Also not sure who or if anyone in the Research Triangle NC area does PEX or if it's even allowed by code. Haven't been able to find any information online or in the phone book for NC specifically, so I guess I would just have to call around.



  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    You can often cut fewer holes if you go up in the attic. Going through the walls means trying to thread pipe through numerous studs and repairing a bunch of wall surface. Running up into the attic and then coming down means just going through the top plate. Going through the attic can give you more concerns about freezing and or excessive temperatures of the cold side in the summer, so it has its issues, too.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3


    So it's still possible to use other methods, but the attic is fewer holes, less hassle, probably less expense, etc. That makes sense! In everything I've read so far everyone just seemed to "assume" the attic was the place to rerout but I never could find out exactly why.

    Thank you!


  4. #4
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default pipe

    The only way to repipe under the slab would be to cut the concrete EVERYWHERE the tubing has to run. The cost would be prohibitive and you would have to move out until the piping was done, the concrete replaced, and then the flooring material installed.

  5. #5
    Plumber Cass's Avatar
    Join Date
    Nov 2005


    I did a repipe on a slab and we ran the pipe on the inside wall up in a corner of the ceiling. Then the owner boxed it in. It does not look bad at all.

  6. #6


    Running it around in the walls was my first thought. No way would I want to break holes all over the slab, at least that would not be my first option. But I'm guessing that dropping pipes down into walls from the top would be easier than snaking them around the bottom or the middle.

    I was thinking about a manifold system for next time. Where do you put a manifold in a slab house? Attached storage shed?


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