The surging L.A. County housing market showed no sign of a letup in July, as sales volume remained strong and the median price of an existing home hit $515,000.

That’s a 20.9 percent increase from one year earlier, when the median home price was $426,000, and a 2.8 percent increase from June’s $501,000, according to data provided by Melville, N.Y.-based HomeData Corp.

Countywide, the number of existing homes sold in L.A. County rose to 9,294 in July, a 3.9 percent increase from 8,949 one year earlier and a 9.9 percent from June, when 8,457 homes were sold.

The continued strength of the housing market defies repeated warnings from economists who say the housing market in markets like L.A., Las Vegas, San Diego and some cities on the East Coast are overheated.

Over the past several years, low long-term interest rates and interest-only payment options have kept monthly payments affordable despite double-digit price increases. In recent weeks, long-term rates have risen by about one-third of a percentage point.

“With the economy doing better now than it was a year ago and an increased variety of loan products out there to keep the monthly payments affordable, demand for homes has remained strong,” said Robert Kleinhenz, deputy chief economist for the California Association of Realtors. He said he expects L.A.-area housing prices to keep rising well into 2006.

The median price for condominium resales in L.A. County rose 15.6 percent to $385,000 from $333,000 in July 2004. Prices were unchanged from June.

The number of condo resales rose 8.9 percent from one year earlier to 2,096, a figure that was nominally higher than the 2,074 condos sold in June.

Median prices were calculated by the Business Journal based on data supplied by

HomeData Corp.