[CaptainYooh]

I know.

P.S. Didn't mean for it to sound arrogant. It has been a normal practice to have common walls and floors in conventional condominium apartment buildings designated as common property. Property lines are usually drawn to separate the "finish" from the "structure" and, under normal circumstances, the floor structure ends at either subfloor level or top of a joist in a wood-frame building (I assume this is the wood-frame building is being discussed here). The other way of doing it is to draw the property line in the middle of the common wall or floor, which makes all parts of it private. In either case, shower waterproofing membrane is installed above the subfloor and is part of the unit. Waterproofing membranes are common property in the roofing and parkade structures.