You ask a very good question. 1) You mentioned mold. Has this been remediated (bleach)? No wood rot? 2) You want this to dry out really good so we would advise leaving it open. 3) After the new installation, have the standard shower "flood test" done and wait 24-48 hours. If all is good, then have them proceed with the repairs to the ceiling. 4) Warranty? The most important thing you can be doing right now is hiring a qualified contractor to do this work and specifying that all work will comply with TCNA standards.

Sorry you are dealing with this. We get too many "leaking into dining room/living room/ basement" calls (not our work). Make sure your contractor knows what he/she is doing and ask how they will be constructing the shower, and document/photograph the stages. Good luck with your project.

Only thing I disagree with is the bleach for mold. Wrong move. All that does is kill the surface mold. It does nothing for the rest of it, this coming from a remediation company I had to call out to a job when we opened up the walls and saw nothing but black. Best thing to use is a dish soap that STATES that it's anti-bacterial. That will kill it all.

Interesting Bill. Just what we have seen over the years. I'll note this as it obviously depends on the severity of the mold problem.

Thanks all. Dragonfly, you raise some good points. We don't have black mold now, because it was on the ceiling where we cut a hole. But I will look at the potential wood rot too.

A few months after I had my master bathroom gutted/remodeled I noticed a leak in the garage below. I was all worried that we had a problem with the shower base and it would all have to be torn out. The GC came out and did testing as suggested by Creative Tile above. Turns out the shower pan was just fine. The plumbing is on an inside wall that had a hanging mirror installed on the other side. The GC had hung the mirror himself and was sure he avoided the plumbing, but it turned out that one of the nails/screws had nicked a pipe. It was a slow leak. They were easily able to take the mirror down, open up the sheetrock, fix the pipe and put everything back together again. No leaks since then.

Agree the plumbing should be checked first.

You should let the shower run as others said. Could be a leak in the pan/drainage but could also be a leak in the upstream end (i.e., shower controls and everything leading from/to it.) This especially when you say it happens after a long shower.