Tougher housing regulations on rental properties have been urged after a warrant of fitness trial failed more than 90 per cent of homes it tested.
Housing advocates and politicians say compulsory minimum standards should be introduced to protect the health and safety of tenants.
The trial assessed 144 properties in Auckland, Tauranga, Wellington, Christchurch and Dunedin, and 94 per cent failed on at least one of the 31 assessment criteria on the checklist.
Darryl Evans, from Mangere Budgeting Services Trust, which advocates for struggling tenants, said he was not surprised by the findings, describing some rental properties as "diabolical".
It was common to find properties with exposed electrical wires and plumbing problems, he said.