The number of highly paid professionals and managers unable to afford to buy a home in Auckland has almost doubled in just over a decade.
The figure jumped from 16,600 in the 2001 Census to 31,100 in 2013 - when house prices began to surge again - according to a report by housing researcher Ian Mitchell.
Prices in Auckland have tripled in the past 15 years, while incomes have risen by only two-thirds.
"We're seeing more and more households that can afford to pay rent but can't afford to buy," Mitchell told the Herald on Sunday.
The Branz-funded report found 78per cent of Aucklanders who were working and renting privately could not afford to buy a home at the 2015 "affordable" benchmark of $610,000. That is based on standard bank lending criteria (a 10 per cent deposit and mortgage repayments no higher than 30 per cent of gross income).
The rapidly growing "cannot afford to buy" group made up 18 per cent of all Auckland households, compared to 12 per cent in 2001.
Mitchell said based on traditional bank lending rules, a household needed to earn about $130,000 a year to buy a $610,000 house and still have a reasonable standard of living - even though many Aucklanders on lower incomes were stretching themselves to borrow more and buy at these prices.
But that probably meant households were getting into home ownership by sacrificing money they would normally keep for expenses such as rates and insurance.
He believed many home buyers were working on dangerously tight budgets.
"One of the big issues is what will happen if interest rates go up by even 2 per cent - in Auckland and to some extent in other regions as well."
He warned the increase in relatively well-off households forced to rent long-term could also make it harder for poorer households to compete for accommodation, increasing overcrowding and demands for housing assistance.
Yesterday Mitchell said in the Weekend Herald that most young house buyers could only break into the Auckland market "if their parents are giving them a couple of hundred thousand dollars for the deposit".
His comments echo warnings last year by independent economist Shamubeel Eaqub that rising prices were creating a "landed gentry" of wealthy home owners, while the "have nots" were permanently shut out.
Act leader David Seymour has expressed similar concerns, saying the only people he knew who could afford to buy a home were lawyers, doctors and engineers who went to Auckland Grammar or St Cuthbert's and had financial help from their parents.
The New Zealand sharemarket reached its highest level in a month.