A few days back, I posted here because I was convinced I had a leak with my tub door. After a shower, water would leak into the subfloor/basement in two areas (at each outside corner of the tub). Well, I installed a new door and I still have the same problem. I eliminated the door from the equation entirely by putting in a shower curtain/rod/liner and still have the leak. I am hoping someone here might be able to help me solve this mystery leak.
I feel pretty confident that I ruled out the supply pipes and drains. This is because I tried redirecting water from the shower head directly to the tub drain (by wrapping a liner around the head) and that worked OK with no leaks. I can take a bath with no problem and the tub looks in good shape, so I don't think there are any leaks in the tub. I have tile walls and have cleaned and re-caulked the wall/tub joints three times over and have the same problem. I've been super-thorough about following good practices with caulking so I'm skeptical it has anything to do with the caulk and the tub/wall joints. I can't get it to leak pouring water over the joints.
Interestingly, I start to get the leak if I wrap the liner around the walls to redirect water into the tub only without hitting anything else directly. Since the tub doesn't appear to have a leak, the only difference I can note is that this test allows the steam to collect on the tile walls. In both this test and in practice, I don't see the leak until after about 20 minutes of usage (my wife and I tend to take showers after each other).
My best theory at the moment is that this has something to do with the steam collecting on the tiles and possibly leaking through hairline cracks in the grout, etc. Could this be happening? This problem seems to be eliminated/minimized by allowing the fan to run for a long time between showers. The grout looks to be in pretty good shape, but there appears to be some hairline cracks. If this could be the issue, would replacing the grout fix this problem, or is this representative of a bigger issue if this is allowed to happen? Any other thoughts?