Parents and their adult children are pooling finances to buy houses that allow them to live separately but under the same roof as a solution to the housing affordability crisis.

Purpose-built "dual residences" with separate dwellings in one building are in demand, as parents see it as the only way for their adult children to own a home.

House values in Auckland are at a record high. The median price is now $955,793 and frustrated buyers are priced out of the market.

Figures compiled by the parliamentary library using REINZ house-price and income data from Statistics NZ, show a median house price/income ratio in Auckland of 9.22. Internationally, a ratio of 3 is considered affordable.


Stuart Shutt from Sentinel Homes said rising prices meant demand was shifting from single-family homes to dual residences.

"People have become a lot more creative to get into the Auckland market and this is the result," Shutt said.

"We are consistently seeing families working together asking for a wing for the parents and a wing for their adult children and their kids. It is completely for affordability."

Shutt said more than one in 10 homes the company built were for an older couple and their adult children and grandchildren.

"In most cases the parents are selling their own home and building something and moving in with their kids," he said.

"They generally go in together on the mortgage and are on the title together."

The homes are popular in new subdivisions and typically feature a four-bedroom family home in one wing and a two-bedroom home in the other wing. The two wings have no internal access and are separated by a firewall.

In Riverhead, north of Auckland, family of five Craig and Brenda Boxall pooled their finances with Brenda's mum Donna Storm, who had recently separated from her husband.

Storm had money from the separation but not enough to buy on her own and the Boxalls couldn't afford a home suitable for their family.

Boxall said the only way everyone could afford to buy what they needed was by doing it together.

"It made sense financially. We pooled our resources and bought something we were really happy with," Boxall said.

Craig and Brenda and their daughters Mikayla, 6, Morgan, 4, and Emelyn, 3, love their new home, especially because it means they see a lot of their grandmother.

"It would be a lie to say it wasn't financial but it is also beneficial because it's important for good relationships with the different generations."

Boxall said the purpose-built house meant his family and his mother-in-law had privacy, including separate entrances.

"It is better than a granny flat tacked on or something dark and dingy downstairs," he said.

The number of families living in the same situation had increased remarkably in the past five years.

"We were the only house like this in our subdivision but there were more in the second."