Couples living without children are expected to drive a huge New Zealand household family increase in the next 20 years, according to Stats New Zealand.
It is forecast NZ will have 2.2 million households by 2038, which is about 500,000 more than the current number.
Population statistics senior manager Peter Dolan said it "reflects population growth from net migration and natural increase, but also population ageing, which is changing our country’s age composition".
"Many more people will be in the age where their children have left the family home. These are the so-called 'empty nesters'," Mr Dolan said.
"The projections suggest we’ll need more houses for these households, but different houses from what we’ve typically built, given the likely growth in one or two-person households."
Family households will still be the biggest proportion of households in all New Zealand regions, but the number is likely to decrease with the aging population driving an increase of one-person households.
Couples living without children are expected to make up over half of the 433,000 extra families expected by 2038.
Currently they are the most common family type in most areas of New Zealand, and that trend is not expected to change in most places.
However, Auckland bucks the trend, with two parent families likely to remain the most common family type.
"We project that 40 per cent of births in New Zealand will be in Auckland up to 2038, and the region will also receive the lion's share of the country's growth from net migration," Mr Dolan said.
"These factors both contribute to growth in the number of families with children."