More people forecast to be unable to buy a house.
The Centre for Housing Research says the intermediate housing market has grown from 72,300 households in 2001 to 187,300 in 2006.
Those are households which the centre defines as being unable to afford the cheapest houses under standard bank lending criteria.
Even under a scenario of slow growth in house prices, author Ian Mitchell says another 32,000 households will be unable by 2016 to buy a house.
Mr Mitchell says that has implications for Government housing policy.