Hi! This is my first post, and I'm already asking for help.

Tl;dr version: I had a toilet shutoff valve leak which swelled either my subfloor, my underlayment, or both. I'm trying to assess the extent of the damage, would like some help on first steps.

Full version: I have a rarely used upstairs bathroom that I was cleaning, and saw some of the floor tiles looked loose. Picked at em a little bit, they popped right up, traced the tiles to a leaking toilet shutoff valve. That, at least, caused the wood to swell and mess up the tile. I would like some help with first steps, and a sanity check.

Problem 1, it looks like the previous homeowner mortared tile directly to what looks like subfloor. If it isn't subfloor, it's underlayment that looks a lot like it, and it has water damage. The spot I examined is about 2' in front of the toilet, but the tile all around that is loose, so I'll probably take a more extensive look. It has swelling and some peeling. Haven't noticed any rot or mildew, but structural changes to the wood are enough for me to be concerned.

Problem 2, while I was looking at things, I noticed that the shower liner creaks when you walk around in it. There's a small wall between the toilet and the shower. I would think that, if the leak had spread through the wall into the subfloor underneath the shower, I would see some kind of staining on the drywall due to capillary action, and I don't see any signs. So this creaking seems to me to be unrelated, but also a matter for concern.

Problem 3, the wall between the shower and the toilet has a column that looks either like it's crooked, or it just had a not-great drywall job done on the upper part. I don't know if I should be concerned about this, or not. It seems unlikely to me that there would be water damage this high. Staining should only spread vertically 18-24" above the natural flow of a leak, from what I understand, and this is 6' or more, so again, probably unrelated.

I'm trying to determine my order of operations here. I intended to remodel this bathroom eventually, just hadn't planned on it yet. But, the toilet doesn't work and the shower sketches me out, and the tile is popping up off the floor, so it probably bumps up a little higher on my list. To evaluate whether the subfloor is damaged, I assume I would remove enough of the tile to investigate, and probably remove the toilet as well? I've done subfloor installation on new construction before, back when I worked in construction, but I never worked on any remodels other than demo, so I don't really know how to evaluate what's damaged.

 

You answered your own question, the toilet comes up, tile comes off, then assess how and where the damage is.

The creaking of the pan, assume acrylic, was probably due to no mortar bed under is so the pan is flexing and making noise but till you take a look you dont know!

Column, have no idea, your the only one that can see the issue!

 

Update on this, I came home from work to find more leaks in that bathroom, water was everywhere. So, I guess I'm taking everything out and starting a bathroom remodel, as the toilet, toilet supply valve, and shower are all evidently leaking.

Shrug. Is what it is. Thank you for the sanity check!