A new strengthened law for prosecuting landlords who rent out unsuitable properties has been passed.

The law deals with unlawful residential properties, such as illegally converted garages or sleep-outs.

Auckland Property Management director Howard Morley told Mike Hosking some of the garage conversions they've seen are pretty rough and not fit for habitation.

He says it's a good way of overcoming the housing shortage but they need to be done properly.

Morley says it's major win for landlords.

“There was a case three years ago tilted the scale in favour of the tenant but they will now be accountable.”