MPs have been told that national standards and registration should be introduced for boarding houses to help lift the quality of the housing.
The Social Services Select Committee is holding an inquiry into boarding houses in New Zealand.
The director of Wellington's Downtown Community Ministry told MPs on Wednesday that boarding house tenants are the largest group of homeless people in the city.
Stephanie McIntyree says they are very vulnerable, particularly as the law is not being enforced to make sure the conditions in the houses are up to stratch.
Some of the boarding houses are squalid and the people staying in them feel powerless because they have nowhere else to live, she says.
