Bath P-Trap Pipe Options

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by gth1, Jan 1, 2011.

  1. gth1

    gth1 New Member

    Messages:
    2
    Location:
    Maryland
    Hello,
    I'm replacing a pedestal sink in my bathroom and want to replace the waste pipe/p-trap as well (the house is 70 yrs old). The old sink had an unsightly combination of pipes, bends and adapters leading to a massive 1.25 inch MPT connection just under the floor level. I'll try to attach photos of the old pipe combination and an example the simpler connection I'd prefer to install. I haven't seen any obvious plumbing solutions at the local hardware store that would allow easy threading into the 1.25 inch MPT outlet in the floor. Any suggestions?

    Cheers, GTH

    http://i1222.photobucket.com/albums/dd482/gth1/DSC01280.jpg
    http://i1222.photobucket.com/albums/dd482/gth1/DSC01281.jpg
    http://i1222.photobucket.com/albums/dd482/gth1/DSC01283.jpg

    Attached Files:

    Last edited by a moderator: Jan 1, 2011
  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,248
    Location:
    Land of Cheese
    Problem #1 is that you have an S-trap, which is no longer permitted by code. To meet the current requirements, the trap will need to be vented. Proper remodel would be to install a drain and vent stack into the wall framing so that a proper horizontal trap arm can be installed into a sanitary tee in the wall.
    If you are not doing a remodel, you should find out if your plumbing code will allow the use of an air admittance valve. Unless you are installing a vanity, you are still going to have the pipes showing under the sink.
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,351
    Location:
    Yakima WA
    Even if an AAV is legal, it will be unsightly because it would have to be under the sink. As Cacher_chick pointed out, you need to go into the wall with a drain and vent stack. You can't hide an AAV in the wall, you have to have access to them since they are mechanical devices and can fail. I don't know of an easy, cheap way to do this.
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I do not agree that it is helpful to recommend opening up the wall and the roof to try to make this 70 year old bathroom conform to current code. Yes, you will have to be careful to keep the S-trap full of water.

    The arrangement you have is about as simple as it will get. I can't see dimensions, but you talk about 1 1/4" below the floor, so I suppose that is a 1 1/2 to 1 1/4 reducer coupling in the photo. No way to get around that. And the extra 90 is to make everything line up. Depending on the new sink or vanity, you will have to use similar to make it all line up. You can get chrome plated fittings to look better.
  5. dlarrivee

    dlarrivee New Member

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    1,172
    Location:
    Canada
    Why not? Doing it right is always more work isn't it...
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    He's just replacing the sink. I don't think we are going to go into every home in America that happens to have old plumbing, and make them spend serious bucks to "fix it up". If he was remodeling the bathroom, that's different. This is not that
  7. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    So it costs "serious bucks" to install 20-30' of pipe, a couple of fittings?
  8. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,351
    Location:
    Yakima WA
    I think you have to realize that it would require open the wall, moving the drain, installing a vent, then closing and refinishing the wall. Guess it depend on what you call "serious bucks". That is what would have to be done to eliminate the S trap and make it right. Would it be worth it? Seems that it has been working OK for 70 years, so you decide if it would be worth the expense.
  9. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Gee thanks for the explanation.

    Nobody in their right mind buys or owns a 70 year old house and expects to be frugal about the inner workings of the home, do they? In the end you get what you pay for.
  10. Basement_Lurker

    Basement_Lurker One who lurks

    Messages:
    668
    Location:
    Victoria, BC
    s-traps are illegal, that's all there is to it.

    owning a home is expensive, and dlarrivee is correct that you should do something right or not do it at all. perhaps the wet wall can be accessed from behind, meaning for a least destructive addition of a vent stack.
  11. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,248
    Location:
    Land of Cheese
    Had he left it alone, most places would "grandfather" it and then no correction would be needed.
    Now that it has been removed, the only proper repair is to bring it up to current code.

    All the better reason to know what one is getting into before starting the job.
  12. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    The legalities of it being left aside, I would personally prefer to remove an S-trap from the home, if it were mine.

    Owning a home comes with expense, owning an older home comes with expense that most folks don't think about.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,684
    Location:
    Cave Creek, Arizona
    Starting with the fact that the drain is an "illegal S trap, and has a "reduction in size" in the direction of flow, then the two elbows are NOT drain fittings, they are the cast brass outlet elbows for sink traps, there is not much about the old drain to recommend it or emmulate with the new one. The drain can be reassembled using a 1 1/4" "S" trap, if you can find one, but you will find that it will PROBABLY gurgle after every usage, regardless of how it has worked for the past 70 years.
  14. gth1

    gth1 New Member

    Messages:
    2
    Location:
    Maryland
    All -

    Thanks for all the replies and I much appreciate the concientious concerns regarding a more in-depth retrofit. I've enjoyed my old house for 17 years and have made my peace with it's dated configurations and quirky modifications made by previous owners. As Jimbo pointed out, the goal is to replace one pedestal sink with another -- I do not plan to rip up flooring, drywall or roof to do so, although I understand why others recommend it. New S-traps appear to be readily available for less than $20. I'll try to make that work. Thanks again!
  15. dlarrivee

    dlarrivee New Member

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    1,172
    Location:
    Canada
    Even with lots of great advice, he's still going to do the typical home-owner repair... Jimbo must be proud.
  16. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,684
    Location:
    Cave Creek, Arizona
    Another case of asking for advice, and then doing EXACTLY what he planned to do in the first place.
  17. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    I'm glad you mentioned the fact that the drain reduces in size as it goes down stream... I'd be even more concerned about that than the S-trap.
  18. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,351
    Location:
    Yakima WA
    Just another case of someone wanting approval for doing what he wants to do even if it's wrong.
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