Building approvals have slumped more than three times faster than expected in August after a plunge in the volatile apartments number, according to official data.
The Australian Bureau of Statistics figures showed the number of buildings approved fell a seasonally adjusted 6.9 per cent in the month to a total of 18,701.
Forecasts by analysts surveyed by Bloomberg predicted a 2 per cent fall in approvals during the month.
The result follows a 4.2 per cent increase in approvals during July.
The figures for August leaves the number of approvals well below March's high-water mark of 19,419 dwellings.
This month's decline was driven by a dive in the approval of 'other dwellings', which includes apartment blocks and townhouses, a volatile figure representing the bulk approval rate for apartment towers.
The figure slumped 11.4 per cent, in seasonally adjusted terms, during the month, to 8,760 dwellings.
Meanwhile, the number of detached homes approved was stronger, increasing 4.9 per cent to 9,765 in August.
Over the 12 months to August, total building approvals were up 5.1 per cent on a seasonally adjusted basis, the ABS said, below of economist expectations of a 7.4 per cent increase.
Over the same period apartment approvals have risen 8.6 per cent, while approvals for private sector houses have lifted 3 per cent.
In trend terms, which strips out month-to-month volatility in the figures, housing approvals have increased 13 per cent over the year to August, after shrinking 0.7 per cent in the month.
However, the trend rate of dwelling approvals has now fallen for six straight months, at a time when the Reserve Bank of Australia is trying to stimulate the economy with record-low interest rates.