Having lived in some midwestern cities with a bunch of extra "not easily converted" warehouses, I've seen lots of "illegal" art collective operations where they just put all the extra plumbing on the ground floor where it is easily retrofitted (you can even raise the floor with a false bottom for plumbing if no other option) and then everyone shares a big kitchen, then the upper floors where retro fitting is more difficult are for habitation. Maybe the HVAC unit is undersized or something, or some other safety factors are substandard due to these people not having the money to improve it further, who gives a shit it is better and safer than living on the streets.

Obviously since it's illegal these aren't advertised but they're quite prevalent, and issues are rare enough that now decade past muh Ghost Ship Warehouse is the constant drum being beat by the brain dead building code worshippers who actually bought the line of bullshit that having people homeless and freezing and shitting in the streets was actually a 'written in blood' advantage.