To remedy that, the carpets should be ripped up and sealant applied to the subfloor, at minimum.There are also tiles in the smaller upstairs bathroom that are lifting up and creating a safety hazard; putting a rug on top is not a sufficient solution.The house is in a condition that materially interferes with the health of household members.

Slate roof or even Spanish tile.

Quote from @Dean Malka: 1) what's your range for remodeling a kitchen completely (granit, backsplash, tiles, etc)?

If the lines are aluminum, we ALWAY replace that like we replace lead paint or lead pipes and asbestos ceiling and tile.  

No, you can jet and cut even with clay tiles as long as your plumber knows what s/he's doing.

What @Nathan Gesner said ^^^^ plus....do you have other construction skills like plumbing/electrical/tile/etc?

i.e. paint, flooring, cabinets, tile, etc.  

Fortunately our remedy was fairly simple, large floor fans and new ceiling tiles but it was a massive inconvenience and the damage would likely be much worse if it repeated in units in other places.

Quote from @Don Miller: Tile installed better late than never !!!

I would assume that it should be blocked off with some type of decorative tile or something of that nature.