The rental market cannot stabilise itself with its "hands tied", a Canterbury University finance and economics lecturer says.
Dr John Fountain said the answer to Christchurch's housing shortage did not lie with increasing the social housing pool, building working men's villages or headleasing properties to underwrite rental costs.
The market "can't and won't solve this problem with its hands tied", he said.
However, adapting existing housing or building "secondary suites" could help.
Dividing sections of large, old homes into self-contained, one or two-bedroom flats was an idea implemented in Fountain's home city, Vancouver, when housing costs rose.
There were now "tens of thousands" secondary suites in the most popular suburbs of Vancouver and Toronto, holding up to 30 per cent of the rental market, he said.
Fountain said there were about 100,000 Christchurch properties that could follow suit and split into two.
Secondary suites in the city would not only take pressure off the rental market by increasing the supply of available accommodation in high-demand suburbs, but there was also a "very strong financial incentive for homeowners".
Home extensions or adaptations were "fully insurable now" and would take only a few months to complete, he said.
The only hurdle was a Christchurch City Council regulation that said residential dwellings could not have a second kitchen.
"I am not asking the Government to do anything except change that one regulation so ordinary people can do this and do it quickly," he said.