The retail giant's record half-year results show runaway property values and blistering summer weather helped drive its total profits from property, furniture and whitegoods 39 per cent higher to $257.29 million.

While the retailer is best known for its sprawling electronics and furniture stores, its earnings from its extensive property holdings spiked 91 per cent, largely from the revaluations.

Without contributions from revaluations, the retailer's profit after tax was up 19.7 per cent to $204.27 million off the back of franchise sales, which grew 5.2 per cent to $2.86 billion.

The result reflected strong retail spending in NSW and Victoria as well as the "wealth effect" of higher house prices and hot weather along the eastern seaboard powering sales of airconditioning units.

Billionaire retailer and chair Gerry Harvey said revaluations would push up to $3 billion in the near future.

Mr Harvey would not provide any details on exactly how many of the Harvey Norman stores are owned by the group, except to say an "awful lot".

Mr Harvey rejected suggestions the business had purchased any of the former Masters sites.

"We had a look at all of them and but we haven't got any interest in any of them. For good reason, they are not in the right areas or we have stores nearby," Mr Harvey said.

The Harvey Norman property empire spans 238 stores in Australia and 85 shops in New Zealand, Singapore, Malaysia, Croatia and Ireland.

The large-format, multi-tenanted Harvey Norman franchise stores, along with a diverse mix of third-party tenants, accounted for nearly half the group's earnings – 54 per cent of its total asset base and about 40 per cent of profits before tax.

At each reporting period, one-sixth of Harvey Norman's investment property portfolio are independently valued, while the remaining five-sixths are reviewed for fair value by the directors.

The entire portfolio is independently valued every three years, the group said.

The retailer said there was no further write-down on its mining camp investments, although it booked a $4.62 million impairment loss on the project.

Over the previous two periods the group has become another casualty of the fading mining boom, writing off $13.2 million from its initial $60 million investment in building transportable accommodation units or "dongas" to house mining camps in remote parts of Australia.

The joint venture between Mr Harvey and unnamed partners ploughed large sums into the dongas just as the resources boom was ending.

Another of Mr Harvey's pet projects, a 49.9 per cent investment in Victorian dairy farm and pedigree breeding operation, Coomboona Holdings, also racked up losses of $3.26 million for the half year.

In the previous corresponding period its losses were $1.79 million.

Future growth is expected to come from Harvey Norman's overseas network as well as its new start-up ventures including the fledgling School Locker business in Australia.

Harvey Norman has recently acquired a property in Dublin and plans to open a signature store there in the next few months and Mr Harvey said the Singapore-Malaysia market could support as many as 30 more stores.