Floor Joist in way of drain for soaking tub

Discussion in 'Shower & Bathtub Forum & Blog' started by Finn12, Jan 7, 2021.

  1. Finn12

    Finn12 New Member

    Jan 7, 2021

    I have just started a bathroom renovation for my second floor bathroom of a house built in 1920. I have a large soaking tub planned that will need to have the drain connected to existing main. The problem is that the main runs parallel to a floor joist (about five inches apart) and the drain will need to be fitted in to the main at a perpendicular angle—i.e., would have to go through the joist. Any thoughts on my options? I don’t like the idea of cutting in to the joist, especially since it’s the joist that will run under the 90 gallon soaking tub once it is installed.

    Any insight is much appreciated!
  2. kevreh

    kevreh New Member

    Oct 17, 2018
    Does the drain need to go THROUGH the joist or is where the drain needs to be the same place as where the joist is? What size joist? Try to post a pic Drilling a hole in joist is ok as long as your 1/3 away from the edge, if memory serves correct. May be an issue with a 2x8.
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  4. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    A picture would help. A tub drain gets a 1.5" vent and p-trap. A 2-1/8" hole through the joist may work for that, keeping it at least 2" from the top and bottom of the joist.
    Sometimes I drop below a joist near a wall and run with the joist. Boxing out at a wall isn't as noticeable.
    What else is the main waste line serving?
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