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Thread: Tub Drain and Floor Joist

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  1. #1
    DIY Member diydude's Avatar
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    Default Tub Drain and Floor Joist

    The new tub I'm installing in my bathroom will be perpendicular to floor joists. The original tub was installed in the same location, but the notch that was cut for the drain and overflow in the floor joist was about 1 1/2" deep. My understanding is that I can't notch any deeper than a little less than 1" (1/6 the depth of the 2x6 joist). What's the best way to approach this situation? I read something about heading off the joist, which would be a pain, since I've already sistered the joist. See included pic.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    FWIW, when you notch a joist, you effectively make the whole joist the equivalent of the thinnest section. The top and bottom are the parts that provide the most strength, either in compression on the top or tension on the bottom. When there's a gap from a notch, the bending moment's location changes and it gets much weaker. That's why there are rules about where it is acceptable to put holes in them (basically, avoid the ends, and limit their diameter). I'd probably box it out, but see what the others have to say.
    Last edited by jadnashua; 01-08-2013 at 08:42 PM. Reason: fixed tension/compression
    Jim DeBruycker
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    DIY Senior Member dlarrivee's Avatar
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    Sorry that you don't want to do any more work (I know you already did some work on the joists).

    Is that seriously a splice on the right hand joist about 4' from the foundation wall?

    Your best bet is a doubled up 2x(8,10,12) whatever you have there, and some joist hangers.

    You use joist hangers to support the header and you sister the joists that the header attaches to.

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    ACO Shower Drain Sales johnfrwhipple's Avatar
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    The stud wall on the right is that a bearing wall? Any point loads coming down on it?

    2"x4"'s a pretty strong but I'm thinking you should have used something like a 4"x6" or 6"x6" fir post instead.

    Strong tie fasteners, hangers there are many ways to go about it. Do you have an engineer giving recommendations? City inspections?

    Water weights about 8 pounds per gallon. That's a lot of weight.

    I'd get the worked looked at by the city before going to deep and check to see if that wall on the right is a bearing wall.

    Looks like it could be a "Do Over" or some more work done to beef things up proper.

    JW


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    Moderator & Master Plumber hj's Avatar
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    Well, the wall on the right cannot be a "bearing wall" because there is nothing underneath it to "bear" on, and since it is on 2x6s it wouldn't support very much anyway. 2x6 s are a very poor floor support unless they are very short. We would have to see a lot more of the structure to determine what is the best route.
    Licensed residential and commercial plumber

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    ACO Shower Drain Sales johnfrwhipple's Avatar
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    Quote Originally Posted by hj View Post
    Well, the wall on the right cannot be a "bearing wall" because there is nothing underneath it to "bear" on, and since it is on 2x6s it wouldn't support very much anyway. 2x6 s are a very poor floor support unless they are very short. We would have to see a lot more of the structure to determine what is the best route.
    HJ your assuming that the wall is not bearing but it is quite common to find a wall like that in a residential home. Often home owners make the mistake of removing structure here. Some builders do as well.

    On our last project downtown a young capenters assistant made this mistake. I called it out right away. The builder thought I was making a big deal of it. Then the structural engineer came in and confirmed my concerns. A simple mistake turned into a full day repair for the contractor.

    The wall to the right could bear the weight of the ceiling studs. Drywall. Above that the roofing truss could be layed over top of that. Not a big deal in the summer but what about a heavy snow year or a re-roof. Stack a wack of shingles in thewrong place and this can affect this framing.

    Looks to me like the subfloor was compromised and the homeowner went in with some 2"x stock and toe screwed them in place. No big deal if there is no weight bearing but if there is then this needs repairing.

    Worth checking into.

    JW


    jfrwhipple@gmail.com - www-no-curb.com - 604 506 6792

    Always get construction advice double checked by your local city hall. Flood Test Every Shower - Every Time.

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    DIY Member diydude's Avatar
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    Quote Originally Posted by johnfrwhipple View Post
    The stud wall on the right is that a bearing wall? Any point loads coming down on it?

    2"x4"'s a pretty strong but I'm thinking you should have used something like a 4"x6" or 6"x6" fir post instead.

    Strong tie fasteners, hangers there are many ways to go about it. Do you have an engineer giving recommendations? City inspections?

    Water weights about 8 pounds per gallon. That's a lot of weight.

    I'd get the worked looked at by the city before going to deep and check to see if that wall on the right is a bearing wall.

    Looks like it could be a "Do Over" or some more work done to beef things up proper.

    JW
    No, I don't believe the wall on the right is load-bearing.

    Quote Originally Posted by dlarrivee View Post
    Sorry that you don't want to do any more work (I know you already did some work on the joists).

    Is that seriously a splice on the right hand joist about 4' from the foundation wall?

    Your best bet is a doubled up 2x(8,10,12) whatever you have there, and some joist hangers.

    You use joist hangers to support the header and you sister the joists that the header attaches to.
    Joist splice: A previous owner tried to repair the floor joist after a leak rotted part of the floor, and he did a terrible job. So, I had to cut out a section of the joist, attach a full-length sister, splice the joist, then sandwich the joist on the opposite side with a second sister.

    If I'm following what you're saying, it seems like you're advocating heading off the joist and boxing the tub drain.

    Closeup of the drain next to the joist:

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    Here's a drawing I saw online for heading off joists. It sounds like I'd have to sister the joist under the wall also if I decide to go this route. I have a couple questions:

    - Is there a such thing as a triple joist hanger, or is there another option? Edit: I saw an LUS26-3 hanger at the hardware store.
    - What is the best way to cut the "triple" joist? Edit: I'm going to see if I can fit a circular saw, attaching a straightedge to the joist as a guide on either side of it.

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    Last edited by Terry; 02-16-2014 at 05:40 PM.

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