Houses should go through a warrant of fitness check to help combat the high rate of rheumatic fever.
Jacinda Ardern (pictured), the Labour spokeswoman for welfare and children, made the call while visiting Whangarei on Friday, where she met with community groups and primary health organisations to discuss child poverty.
"People think that living in state houses means child poverty, but this isn't always the case," said Ms Adern.
She said there was not enough focus being placed on ensuring private rentals were dry and warm and that it was a leading factor in the ill-health of Northland children.
She said a test approach, similar to a warrant of fitness for cars, should be undertaken before a property is eligible for leasing.
The test could approve insulation and heating, which are especially necessary in Northland where rheumatic fever, a Third World disease, is present in 78 out of 100,000 5- to 15-year-olds each year.