Ageing baby-boomers, dubbed "grey nomads", are retiring to caravans and motorhomes in Nelson and Tasman, rather than conventional houses or retirement homes.

Tahuna Beach Holiday Park manager Ann Cumpstone said half of its permanent residents were aged 65 or older. The oldest was 91.

About 50 retired residents chose to live in a caravan or attached unit rather than live in a conventional property or retirement home.

The trend had become noticeable in the past few years and there was a waiting list of 25 people, most of whom were also older than 65, Cumpstone said.

"We have people who have money and they want a permanent site for a caravan and unit. They don't want to spend $400,000 living in a modern big house."

Nelson needed more land or accommodation developed specifically for retired people, allowing them to rent or buy a small house or hassle-free section, before they were ready for a retirement home, she said.

Nelson Tasman Housing Trust co-ordinator Patrick Steer said Nelson urgently needed a housing strategy, based on housing assessment needs, to better suit the area's ageing population.

The "grey nomads" phenomenon of Australia - a term describing the ageing, transient population - was already appearing in New Zealand and showed up the region's changing housing needs.

"The grey nomads travelling around in caravans or motorhomes - it's happening here in New Zealand. There are just not as many yet and Australia is a lot bigger," Steer said.

Maitai Valley Motor Camp manager Carol Wood was already noticing the grey nomads of New Zealand, saying the camp had several retired regulars living in caravans and motorhomes for a few months before moving on to another location.

Steer said the Nelson and Tasman councils were unaware of the true extent of the region's affordable housing needs and the impact the region's ageing population would have on accommodation.

Already there were 40 people aged 55 or older, 17 of whom were single women living alone, waiting to get into Nelson City Council's 142 community housing units, Steer said.

The Tasman District Council has a waiting list of 58 people aged 55 or older for pensioner units in Motueka and Richmond, where it has 111 units.

A report looking at Nelson's increasing housing needs was included in the city council's social wellbeing policy, currently being implemented.

Council planning and policy manager Nicky McDonald said an extract on housing had been included, recognising the impact it had on social issues and how housing needs were changing.

By 2031, it was estimated up to another 7300 houses would be needed in Nelson, the policy said.

This was mainly because of the area's ageing population - all age groups are declining, except those 65 years and older - while house prices have increased 70 per cent between 2002 and 2004.

"Average household size is projected to drop from 2.4 in 2006 to 2.1 by 2031, with a projected increase in one-person households.

"More housing will be needed, with projections ranging from a low estimate of 1800 to a high estimate of 7300 by 2031," the policy says.

However, despite these estimates, fewer small and affordable houses were being built to accommodate shrinking households. It meant the price of existing small homes remained high and out of reach for some, the policy said.

Nelson councillor Gail Collingwood said it was perhaps time for the council to take another look at whether it needed to expand its pensioner housing.