PRIME Minister Tony Abbott has urged would-be homebuyers to be ambitious but not "over-extend yourself", after defending Joe Hockey's comments that people should get a good job to afford a house.

Mr Hockey on Tuesday prompted a social media furore after he said people needed to get a good paying job to buy a home, rejecting claims of a housing bubble in Sydney.

Mr Abbott said on Wednesday he did not want to respond to questions about the comments.

However, he said that even he, as a Cabinet minister, had sometimes struggled to pay a Sydney mortgage.

"So the Abbott family certainly understands what it's like to have a mortgage. We still have a mortgage," he said.

Mr Abbott said potential first home buyers should be "ambitious" but not over-extend themselves in trying to buy a house, and he believed that was the message Mr Hockey had for people on Tuesday.

Despite the prime minister's efforts to hose down claims of a property bubble, Reserve Bank governor Glenn Stevens said the Sydney property market was "crazy".

After a speech in Brisbane, where he described the economy's performance as "disappointing", Mr Stevens said the Sydney property market was "acutely concerning" and that it was a social problem along with an economic one.

Amid the debate, the Housing Industry Association has called on the Abbott government to establish a national Housing Minister to oversee a strategy to help state governments release more land.

The residential building lobby called for "national leadership", which was required to address land supply, taxes and help improve planning.