Some of Dunedin's worst houses should be demolished and new, affordable ones built for low income residents, according to a housing researcher.
A survey by Presbyterian Support Otago found little improvement since its last survey in 2004.
The survey of 105 houses for a variety of quality indicators showed around half of them had deteriorated in at least one respect since 2004.
The report's author Dennis Rovey said some houses were so badly maintained that they should be torn down.
"They're in situations where you could spend as much as you liked on insulation or other means of tarting them up to sell but they would still be fundamentally bad."
The houses were sitting in areas that are susceptible to damp or flooding.