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Thread: whirlpool drain

  1. #1

    Default whirlpool drain

    Hi all - I hope someone can help. I have a roughed in bathroom in my lower level (concrete slab floor). There is a tub dap out (horizontal 2" in a 9"/12" hole in the slab). Whirlpool drain will be about 3 1/2 ft. from the hole in the slab. Is it within code to raise the whirlpool about 6" (on concrete - so a trap will fit), trap directly under the tub waste outlet, then run horizontal 3 1/2 ft. and connect down into the hole? The run will be under the tub deck, so I can support it any way I need to. There is also a 5" or 6" (big) vertical drain pipe about 2 ft. from the tub waste opening, where all the upstairs (2 full baths) drain into, it also vents out the roof. If I can't connect down into the hole, can I use the same setup as above and tie into the vertical drain (tee or wye). For either, will I need to vent it separately.
    House was built about 9 years ago with a toilet, the tub dap out, and a vertical vanity drain/vent (in addition to the one for upstairs - 2" drain 1 1/2 " vent). As a last resort could I break out concrete (ouch) from the old tub stub out to where I need the new one and run a horizontal 2" and trap right into there? Again, would I need to vent this separately?

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


    As long as you can provide a slope of 1/4" per foot of the horizontal run, you could do this...but, unless you like to climb up into the tub, you'd be better off cracking some concrete to move the drain; it really isn't that hard unless you have a tensioned slab. Once you've got it opened up, you can find out if you have an adequate vent. It does need to be vented, and depending on how the other fixtures are vented, you may be close enough for the tub as well and not require an additional one.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Member breplum's Avatar
    Join Date
    Oct 2004
    San Francisco Bay Area


    Without breaking concrete or changing tub styles, it would NOT be code to run a p-trapped line from the raised tub over and down to the 9 x 12 boxed out drain area. The p-trap wouldn't have a vent in the right place.

    The p-trap belongs in that boxed out drain area to meet code and work properly.


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