Shoddy buildings are going up in Auckland as the council struggles with "significant" quality issues including unskilled construction workers without proper supervision.

More land is being opened up for development in an effort to take some heat out of the property market, but Auckland Council are seeing serious problems at some sites.

"We have some significant industry quality issues that we are struggling with as well, as evidenced by [the fact] between 25 and 40 per cent of all building inspections continue to fail," said Ian McCormick, who oversees Auckland Council's building consenting.

"There is a real shortage of people working in the industry at the moment in Auckland. What we are seeing is large numbers of relatively unskilled folk coming into the market, often not supervised to the degree they need to be, and that's contributing to some of the quality issues that we are currently seeing."

Mr McCormick said his inspectors dealt with cases of non-compliance that came about when very good builders failed to properly supervise subcontractors.

"There is no way with a 25 to 40 per cent failure rate on building inspections that I can put my hand on my heart and say, 'we are picking up every piece of non-compliant work that is actually out there', because I am absolutely certain we are not."

Asked after the meeting about trends in the failure rate, Mr McCormick said it fluctuated but was "getting a little bit worse".

Dave Kelly, chief executive of the Master Builders Association, said they were keen to work with the council on the development of a quality assurance system.