Economist Paul Dales of Capital Economics in Australia said Australian prices would inevitably fall due to how far they had risen compared to disposable income.
"We suspect that the catalyst will be interest rates, although that trigger won't be pulled until 2018 at the earliest," he said.
A United States-style housing collapse won't happen, he says, but he is concerned.
"We are more worried than most and suspect that, after hardly rising at all over the next couple of years, house prices in Australia will fall outright in both 2019 and 2020," he said.
Changes here could well be quicker than that.
Alexander's latest BNZ Weekly Commentary picked our boom to end sometime between late next year and mid-2018, sparked by a combination of factors but particularly the end of falling interest rates.
That would be replaced by worries about rising interest rates, he has predicted.
But slowing net inward migration, increased supply of housing and restricted bank lending to investors were other reasons for the change, Alexander says.
Brian Gaynor of Milford Asset Management says here's no question that housing poses New Zealand's biggest debt risk.
Economist Shamubeel Eaqub says we have a banking system designed to view lending for property as less risky than other kinds of lending.
What happened to the US housing market in the global financial crisis provides a sobering example. But in New Zealand it could be even worse, Eaqub has predicted.
