I appreciate any help with my problem below. I have a PVC drain pipe that is leaking. The drain pipe is from a tiled shower floor. It looks like the joist is pressed up against the pipe elbow and caused it to start leaking. The joist is a 2x10 and the preexisting notch is ~2" from one end of the joist. The joist spans about 10-12' (I didn't measure it when I was down there).

Questions: 1. What's the best way to cut the joist so it doesn't rub against the pipe? Can I just expand the existing cutout? 1. What is the best tool to use for this? 2. What's the best method to repair the PVC pipe? I've been reading about epoxy putty or silicone tape. Thank you

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I disagree that it is the joist causing the issue. When installed, they would have notched the joist so that the plumbing fit and there is no reason that the joist would have moved or expanded in size.

Related, the drain might not even be the source of the leak. While visually it appears that the leak is there, the problem might be elsewhere. Consider that you have tile and it is sloped to the drain. The tile is placed on backing, the backing is what provides the support and the slope. That backing is waterproofed. It could very well be that the waterproofing has failed and that the water is following the slope to the drain. Or that the waterproofing has failed at the drain.

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    Thank you. The joist is right against the elbow. The leaks are coming from the upper and lower joint of the elbow (where the PVC cement is). I think the settling of the house caused it? House was built in 2003. – Julian Mar 29 at 18:47
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    Should add that I can definitely see the leak occurring from the 2 elbow connections/joints when I'm down in the crawlspace and someone turns the shower on. – Julian Mar 29 at 18:53
  • Ok, very good. It sounds like a confirmation that it's the joint, and this is so much better than a failed waterproof membrane. Wood does shrink and houses do settle because of it for a while after being constructed. You noted that you are near the end of a short span for that sized joist so floor movement isn't an issue. Still, it is not the joist, even though it really feels like it is. It is a failed joint. The glue isn't glue, it actually melts the pvc and welds it together. More in next comment – Ack Mar 29 at 19:26
  • PVC joints can't be redone, since they are welded together. Normal practice is to remove the parts and replace with new ones. HOWEVER, your situation is that it is really not a friendly situation to do so. The good news is at least that it is not a pressurized situation. You could weld a piece of PVC onto the joint at the leak, creating a new layer of PVC over it. You could use a waterproof-ish tape like Gorilla tape (fellow site users dislike incoming...). In either case, let it dry first. – Ack Mar 29 at 19:32
  • You can remove some wood with a razor blade knife or hammer and chisel. You don't need to remove much, all you need is a gap between the wood and the joint. The razor knife is more muscle work but safer, the hammer and chisel is less muscle but more likely to cause damage on user error and it might be hard to get the tools in there to do the work. I suspect a few minutes with the knife is enough. Cut across the grain on each sides, then pick out the middle with the tip – Ack Mar 29 at 19:34

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