P-Trap into floor drain? Or is that an S-Trap? (and not good)

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by bretm1, Apr 21, 2011.

  1. bretm1

    bretm1 New Member

    Messages:
    1
    Location:
    Massachusetts
    Hello

    First post. Did some searching, but couldn't get clear. I am "fairly" skilled but am not a pro. Just a do it yourself type. I am in Mass, have replaced a vanity in bathroom on second floor in a house built in early 1900's. The existing vanity has been there for 10-15 years. Of course the new vanity doesn't line up with the drain but I can deal with that, but the drain is on the floor (vertical?) going staight down to somewhere. I can not tell if there is P Trap under the floor unless I rip the floor up. Do I need to do this?

    Am I "stuck" with having to use an S-Trap (which may not be to code) because the drain is in the floor? I'm assuming that because I have to take the "P"Trap and then come off with a ninety degree elbow to the floor that this essentially creates an S-Trap. The trap I removed was like this. Not sure if I go straight off the P and then down if that will make a difference, but there is no room to do this. We have been in the house five years and never smelled anything, but I know that may not mean much.

    I'm kind of confused. Sorry If I didn't search well enough. Input appreciated

    Thanks
  2. SacCity

    SacCity In the Trades

    Messages:
    189
    Location:
    Sacramento, CA
    Sounds like an S trap.
    However there is always the Grandfather clause,
    As long as it was legal when done you don't have to change it,
    But if you touch the plumbing in the walls you will have to bring it up to current code...
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,051
    Location:
    New England
    Some inspectors would treat changing the sink and vanity as new, and require all of the stuff to meet current codes. There is a limit on how long the drop from the sink can be before it hits the trap. Having a trap below the floor is likely to be longer than allowed unless the sink is very deep and the vanity is on the low side. Plus, in MA, it is generally illegal for a homeowner to do plumbing without a license, even in their own home.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,680
    Location:
    Cave Creek, Arizona
    "New" or "old", you still have an "S" trap. The only way NOT to have an "S" trap is to install an AAV at the point where it turns down.
  5. SacCity

    SacCity In the Trades

    Messages:
    189
    Location:
    Sacramento, CA
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