Latest figures from the annual Demographia affordability survey underline the strength of the housing market.
They show the median New Zealand house price costs 5.3 times gross annual median household income compared with 5.2 last year.
A contributing factor is falling incomes nationally, as recorded by Statistics New Zealand, except in Christchurch.
Demographia rates housing affordability based on a median multiple – median house price divided by the gross annual median household income.
Co-author Hugh Pavletich claims that if housing exceeds three times annual household incomes it presages a housing bubble requiring political intervention to free up supply of housing.
The position is worse for homeowners in Auckland where the median multiple is 8.0 compared with 6.7 last year.
That places Auckland as the seventh "least affordable" of the 85 centres surveyed with populations of more than one million.
By comparison, Sydney ranks 9.0, Melbourne 8.4, and Australia's national median is 5.5. Among the most affordable cities are in the US; Pittsburgh (2.3), and Atlanta and Indianapolis at 2.7. Hong Kong topped the table, with a median multiple of 14.9.
The Christchurch multiple is 5.8 due to rising incomes there.
The figures may hearten some homeowners because higher values of homes may reduce the proportion of household debt.
But the figures represent greater hurdles for first home buyers.