Reserve Bank Governor Graeme Wheeler said high housing demand was being underpinned by easier credit conditions, both in terms of lower mortgage rates and an increased willingness by banks to lend at high loan-to-value ratios.
"Our concerns are shared by the OECD and by the IMF in its recent review of the New Zealand economy. Housing risks have also been noted recently by all three of the major international credit rating agencies," Mr Wheeler said.
Deputy governor Grant Spencer said the Reserve Bank wanted to ensure that bank capital requirements reflect the risks around housing lending.
David Whitburn, president of the Auckland Property Investors Association, predicts price drops.
"If highly geared [over 80 per cent] loans are restricted, then there is no question that this will restrict house price growth. This move will not stop property cycles but will, in all likelihood, slow down Auckland house price growth, and raise rents in the lower-mid house price levels, as fewer people will be able to finance their own homes," Mr Whitburn said.
ANZ economists Cameron Bagrie and Mark Smith said the changes were "a strong signal that the Reserve Bank has put another bullet in the chamber and are prepared to do what is necessary to prevent a boom-bust property cycle eventuating".
What's changing?
* Reserve Bank is moving on the big four banks: ANZ, Westpac, BNZ and ASB.
* The banks will need more capital to back mortgages where the borrower's deposit is less than 20 per cent.
* The new rules kick in from September 30.
Source: Reserve Bank