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I noticed that my bathroom floor was sagging and discovered a floor joist underneath the bathroom has a considerable sag to it. From the looks of it, the floor joist was previously sistered and used a piece of angled metal to tie it in to another joist. I'm hesitant to call the angled metal a joist hanger because it doesn't allow the joist to hang on it underneath.

This metal piece was cut at some point to accommodate for a water supply line for the shower in the bathroom. I believe this is what caused the floor to sag in the bathroom. As you can see in the pictures, there isn't room for me to jack the joist up and add a joist hanger in there because the water supply line is in the way. I'd like to avoid moving the water supply line because I do not know how else to route it and there is no access to the water line behind the shower (an issue on it's own).

How should I go about raising and securing the joist?

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2 Answers 2

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Move the water line. I realize that you don't want to, but you have to--if only a little. A small offset of a couple inches will allow you to fix the framing problem. Start with an elbow just below the subfloor.

  1. Remove the vestigial metal bits.

  2. Temporarily cut the water line below the subfloor, leaving enough protruding to connect a fitting. About 1" is enough. Take care to not damage or deform the stub as you'll only get one shot at reconnecting to it. Clean up the pipe well with emery cloth.

  3. Install a 90° elbow, which could be a push-to-fit type, along with a short horizontal pipe along the beam and another 90 oriented downward. You can clip the corner of the joist just enough to clear the pipe elbow. It won't affect performance.

  4. Jack up the joist. It won't take much; even the scissor jack in your car will do. Use a 4x4 post or a pair of 2x4s in a tee configuration, fastened together well. Examine the floor above to get the right position, or set it flush with the beam on top.

  5. Install a proper (double) hanger, using hanger nails or 16d framing nails as specified and filling all provided holes.

  6. Reconnect the water line with another 90° elbow below the beam and a 22½° elbow to get around the large drain pipe and back to the original route (the lower 90 can be swiveled accordingly).

Tips:

  • Prep is key with plumbing. Clean your pipe and fittings to baby-butt smooth and flux them well.

  • Whe sweating joints against wood use scrap sheet metal to avoid getting smoky and leaving unsightly char.

  • Pre-fit all your parts before soldering. Be sure no part is under stress, as this can cause cracking over time.

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    Or use crimp fittings and avoid the hot work.
    – Dale M
    Commented Mar 25 at 20:08
  • I'm not familiar with crimpers. Think they'd fit in this scenario?
    – isherwood
    Commented Mar 25 at 20:56
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    Looks like there’s enough room. If there isn’t, a shark bite style fitting would probably be fine. You’d need to get the paint off the pipes either way.
    – Dale M
    Commented Mar 25 at 21:00
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Instead of hanging it, support the joist from underneath with an adjustable house floor jack (an example, not endorsement).

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  • 2
    Sometimes this is a good strategy, but in this case the only place such a post could go is in the stairwell.
    – isherwood
    Commented Mar 25 at 13:36
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    I had the impression that the joist was over the floor, not the stair steps - and envisioned the jack under the very end of the joist (there's a pipe there, but it looks easy to move). Is that wrong?
    – MadMonty
    Commented Mar 25 at 13:54
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    I wanted to avoid moving the vertical pipe passing through the floor, which I understand to motivate the butchered hanger (per OP, "I do not know how else to route it and there is no access to the water line behind the shower"). The pipe I would move is the horizontal, running perpendicular to the sagging joist. I suppose one could fashion a saddle around it instead, but I wouldn't invite Murphy into my house if I could help it ;). That said, I liked your careful explanation and tips - that would be the best solution in the long run if one can get to all the needed locations.
    – MadMonty
    Commented Mar 25 at 14:06
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    I thought about using the floor jack too. The joist is over the floor so I could install the jack there. I was worried because I read those should only be installed as a temporary solution. I think I'll have to notch out the joist a bit and call a plumber to get the pipe rerouted.
    – Niko
    Commented Mar 25 at 14:20
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    Not to get too deep into the weeds, but "over the floor" isn't your requirement. Technically you should have a footing under any post, and not just the slab (which can crack and settle). It may work fine for a single joist, but it may not.
    – isherwood
    Commented Mar 25 at 14:22

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