In a bathroom, that almost always involves the floor and, specifically, the membrane that sits between the tiles and the concrete slab. The same applies to walls between your flat and next-door or common property.
Leaking membranes are still among the most common defects in new buildings, so you can understand why owners corporations (bodies corporate) want some guarantees that the buck stops with you when the apartment downstairs acquires a water feature in its ceiling.
And this is where we hit the first distinction between well-run and badly run blocks. The former will set up a one-size-fits-all bylaw to which owners must sign up before they start work.
This is paid for by the owners corp, which may be slightly unfair on owners who have no immediate wish to renovate, but they will, sooner or later.
In a poorly run building, every renovator needs an individual by-law written by