Builders say an increasing number of homeowners are refusing to pay when their house is built.
Some people cannot afford to pay their bills but others simply refuse to honour their contract.
One industry figure says it's costing more than $200 million per year and another says the trend is forcing builders out of the trade.
Certified Builders Association director Geoff Hardy says a growing number of people are professional debtors, who simply refuse to pay for the work.
The Registered Master Builders Federation says a survey it commissioned revealed 18% of builders had been refused payment between six and 20 times over a five-year period.
The Home Owners & Buyers Association says many disagreements about payment arise because of poor workmanship.