Possible damp ceiling possibly, how to debug next? [closed]

Question

I am debugging this completely remotely from the actual house :(. Tenants talk about a damp ceiling corner and were originally scared about the 'bowing' in the ceiling BUT after they showed me a picture with two vents and one vent had a gap, taking the vent off revealed a crappy job on patching the drywall. However, I am wondering if that was there from some leak previously.

I told them to wait three days with the shower above that one off(since it is guest bath and they don't use it much) and then check if dry again.

I realize this is probably not enough info so I am generally looking for random ideas before having someone drill a hole and actually check if the other side is wet. If we do a drill a hole and it's dry, some combination of using the shower every day may need to be tried (isolating leak to before or after the turn-on valves).

Any other ideas before we have someone cut into the drywall are very much welcome or is this pretty exhaustive?

thanks, Dean

Answer 1

If you want a quick diagnosis, instead of not using the shower above and waiting for spot to dry, have them use the upstairs shower exclusively - even turn the tub faucet on extra - and monitor the spot. It’s obviously not a large leak or else you’d know right away when someone uses the upstairs shower.

If it gets worse when using upstairs a lot more, you likely have a drain leak in the upstairs shower drain. Possibly the rubber gasket between the tub and drain shoe needs replacing.