The cost of a new house rose by a record $76,715 in April as supply chain and labour shortages added to the costs for home builders, prompting a warning that more builders would go bankrupt, crunched between soaring prices and fixed-price home contracts.

The $76,715 average surge in cost from a year earlier lifted the average value of new homes approved over the $400,000 mark nationally for the first time and also increased the pressure on home builders committed to fixed-price contracts signed with clients before costs surged, economist Maree Kilroy said.