looking for info on laundry room floor drain

Discussion in 'Remodel Forum & Blog' started by acr_scout, Apr 28, 2010.

  1. acr_scout

    acr_scout DIY Junior Member

    Manassas, VA
    I guess this is a two part question.

    The first, the local code does not require a floor drain in the laundry but being paranoid as I am I want a floor drain. What are some of the pros and cons of a floor drain.

    The second, if a floor drain must have a P-trap for sewer gases how do you keep the trap primed? From what I understand, the floor drain needs a dedicated line to the main drain for the house.

    Now a side question but I believe this is legal, can I vent the floor drain back into the washer drain vent above the washer drain?

  2. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    The floor drain would have a p-trap to prevent sewer gas.
    It would need to be vented, and the vent can tie back into the washer vent, at 6" above the flood level of the fixture.
    The floor drain would need a trap primer to keep it wet.
    Two ways to do this are"
    A dedicated trap primer connected to the water supply.
    A tee on the standpipe of the washer that diverts water to the p-trap. Everytime you run a load, a bit of water would wind up at the p-trap from the water being discharged.
  3. acr_scout

    acr_scout DIY Junior Member

    Manassas, VA
    Thank you for your input.

    Will the floor drain need to be plumbed all the way back to the main drain by itself or can it be run into the drain for the washing machine?

    The run back to the main drain is about 40 linear feet and at a 1/4" per foot that is a big drop. Any comments?
  4. Esquire

    Esquire Plumber

    Is this in the code or is it just another way that people have derived from years of experience? Would you just invert a tee or or even a dishwasher wye and then connect that to the trap seal primer inlet?
  5. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona
    Depending on where the floor drain is in the building, you could run a line from it to the exterior of the house, or into the garage (through the "step up"), and not need a "P" trap OR trap primer. If you do connect it to the house system, it needs to be done just as if it were a sink or any other fixture, with the added requirement for a trap primer. And since few trap primers work as advertised you might still have to pour water into it periodically.
  6. Pro: water has a place to go, when you clean up which happens often, and if anything springs a leak which may only happen once but causes massive disturbance.

    I have floor drains in my bathrooms. I put them far off center so they are less visible.
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