"We're coming from the house point of view but the expectation of space is bigger. When I was a kid, people would share bedrooms but now it is uncommon for kids to share. People might say I have got two children but I want four bedrooms."
Statistics NZ researcher Rosemary Goodyear said there were several reasons why fewer people were living under the same roof.
"Households have changed. Our families are smaller, and - partly because of our ageing population - there are more couple-only and one-person households."
But one Rotorua family are bucking the trend, with about 10 family members and their partners all living in one six-bedroom property.
Family matriarch Tanya Warren said it was at times chaotic, but she would not have it any other way.
"I've been used to having people around," she said.
"I always get a surprised look or comment when we we tell them we've got six children ... as well as the dogs and pigs - it's dysfunctional as, but it's our dysfunctional."
She added: "The negatives are they eat so it's a pretty big shopping trip, but they are pretty good at contributing now."
