Investor Arthur Panos learned in September that he, along with other owners of the four apartments in a building in Sydney’s inner west, would have to fix the waterproofing of the largely problem-free property. The bill? $500,000.

The NSW Design and Building Practitioners Act 2020 imposes obligations on apartment owners to follow tougher repair requirements, such as appointing a licensed practitioner for repairs that cost more than $5000.