New housing starts fell 13.6 percent in the third quarter compared with the same period a year earlier, a report by a private research firm that follows the construction industry said.

Starts fell to 371,042 units in the July through September period from 429,376 starts in the same period in 1987, according to the report from the F.W. Dodge Group of McGraw-Hill Information Services Co.The decline was concentrated in multifamily housing construction, Dodge vice president and economist George A. Christie said Monday.

"Since the 1985 peak of the apartment building boom, new construction has been scaled back by nearly half, but vacancy rates have only recently begun to recede from their 20-year high," he said.

He said stability of mortgage rates in the 10 percent to 10.5 percent range has supported a fairly steady volume of single-fanily homebuilding this year.

Leading the list of most active housing areas was Washington, D.C., at 12,846 new units, followed by the Riverside-San Bernardino area at 11,103.

In third place was the Los Angeles-Long Beach area at 10,320 units, followed by Atlanta at 10,071 and Philadelphia at 7,469.

Rounding out the Top 10 were: Chicago, 7,295 units; Detroit, 6,980; Minneapolis-St. Paul, 6,037; Seattle, 6,022; and Phoenix, 5,021.