It comes as TradeMe's Rental Property Index shows the national median weekly rent reached a record-breaking 580 dollars in April.
It was the second month rents jumped seven-per cent year on year, with tenants paying 40 dollars more than this time last year.
TradeMe's Gavin Lloyd says one of the reasons that are big problems is that a lot of costs are being put into the market.
He says the other issue is the chronic shortage of housing around the country, which has had a significant impact.
