A key part of the NSW government's plan to fix the state's building-standards crisis rests on credit rating agencies developing for free a new risk-rating tool they will be able to sell to prospective apartment buyers.

Having grappled for more than 12 months with the fallout from three evacuated buildings and abandoned apartments that have trashed confidence in the industry, the Berejiklian government announced on Monday new powers for the Building Commissioner to use the rating tool to select sites to audit and halt dodgy apartment projects.

The Herald understands that US-giant Equifax has been looking into the project, while several other global agencies were surprised to learn of the proposal and expressed reservations.

Among the concerns raised was that the tool would be venturing outside the industry's sphere of expertise, which generally focuses on credit risks, and the difficulty in obtaining information about defective buildings and phoenixing developers.