@Lady Penelope said:
” … compliance with the Building Code of Australia is not retrospective. Under the Environmental Planning and Assessment Act 1979, a building only has to comply with the Building Code of Australia at the time of construction. As a result, the Building Code of Australia does not require you to continually update your windows, balcony railings and fire doors etc.”
I think that means you don’t have to replace and upgrade whenever you discover that something in the building is non-compliant. However, I think whenever you have to replace something that’s non-compliant for some other reason – such as, it’s broken – it must be with something that is compliant with the new standards.