The high-end segment of the housing markets is experiencing a steady growth in values, which might be driven by cashed-up expats, according to the Property Investment Professionals of Australia (PIPA).

The upper quartile of the dwelling market has posted a 3.7% increase in values over the past month, according to new data from CoreLogic.

Peter Koulizos, chairperson of PIPA, said expats were returning home with plenty of cash, often in stronger currencies that boost their buying power.

"Expats from expensive cities like London, Hong Kong and New York often don't consider our real estate prices unaffordable and are happy to pay what is necessary to secure a prestigious property in a desirable location," he said.

Sale prices in Sydney, for instance, seem "insane" based on the observation of PIPA members, Koulizos said. CoreLogic data show that prices in Sydney's higher end increased by 4.8% over the month, stronger than the 2.2% gain in the lower quartile.

Some capital cities also reported higher gains in the upper quartile compared to the lower end of the market, including Melbourne (2.8% versus 1.6%) and Brisbane (3.1% versus 1.1%).

"Some properties are selling for hundreds of thousands of dollars more than what anyone — including experts — had predicted, which is leaving sellers very happy, but many buyers and property investment professionals scratching their heads somewhat,” Koulizos said.