Wairarapa landlords will be "punished" with extra costs if warrants of fitness are made compulsory for all rental properties, a local property manager says.
State houses will have to be leak-free, well-ventilated and contain an electric light in each room to get a warrant of fitness under a trial which will determine whether the scheme is extended to all rental properties.
But critics argue housing upgrades in the private sector would end up costing the people they were designed to help.
Housing Minister Nick Smith launched the trial, which will evaluate 500 state houses.
Wairarapa has only one state house, which won't be part of the trial.