RP Data has previewed upcoming house price data, saying little recovery is expected in August.

With the research company's August Home Price Index due this Friday, RP Data national research director Tim Lawless has indicated the market is expected to continue a trend of weakness.

July's results showed capital city home values down 0.6% for the month, and down 2.9% for the 12 months to July. Lawless said home values across capital cities have been declining around 0.4% month-to-month over the six months to July, and that August data is not expected to show a reversal of the trend.

"The results for August are likely to show a continuation of the soft trend that has been evident since the start of 2011," Lawless commented.