IN THE BUSINESS . . . Area new home sales for July slipped 8.5 percent from June but still recorded a 30 percent gain over the same period a year ago, according to Housing Data Reports, which monitors sales here. Sales of new detached or town houses dropped 14 percent from the June rate, while condos held their own, HDR reported. And it noted that the average price of a new detached or town house is actually down slightly from a year ago, to $112,600 from $115,900. HDR attributed the decline to the recent jump in interest rates and the normally slow summer season. It foresees an improvement soon . . . Meanwhile, the Northern Virginia Board of Realtors has its sales figures in for August (covering all homes, not just new ones), and it has recorded a 47 percent rise from a year ago, with prices up 5 percent to $105,600 on the average. The board's figures showed that 14 percent of the units sold were condos, at an average price of $70,380; the average price for the other 86 percent was $109,502 . . . Likewise, the Montgomery County Board of Realtors' figures show a 57 percent jump for this August over last, with a median sale price of $107,000 . . . Interstate General Corp. has begun construction on a 468-unit luxury rental community in Germantown. To be known as Rolling Hills, the 40-acre project will feature private deck tennis courts, a swimming pool and electronically controlled entranceways . . . Signature Communities, Inc., has started 24 town houses, to be called the Vistas at Waterside, in Lake Ridge along the Fairfax-Prince William line. Offering views of Lake Occoquan, the houses will range from 1,560 to 1,672 square feet and be priced from the upper $80,000s . . . The Montgomery County Housing Opportunities Commission has opened its public housing and Section 8 rental assistance waiting lists for the first time in two years. The commission is asking interested persons to call 942-0902 to hear a five-minute tape that will explain eligibility and application procedures. Applications can be obtained by calling 933-9750, ext. 258 . . . DRG Financial Corp. has placed a $16.3 million loan with Mutual Benefit Life Insurance Co. on the Embassy Row Hotel. The loan is to be used to refinance debt and to pay for extensive renovations of the hotel, located at 2015 Massachusetts Ave. NW. The Embassy Row is owned by Lincoln Hotel Corp. of Dallas . . . The George Hyman Construction Co. has been chosen to build the new Democratic National Headquarters building at the corner of Canal and Ivy streets SE. The four-story, 42,000-square-foot building will cost $4.66 million.

PERSONNEL FILE . . . The U.S. League of Savings Institutions has nominated Paul W. Prior, of New Castle, Ind., to be its chairman, and has picked John B. Zellars, of Atlanta, to succeed Prior as vice chairman. Both will be formally elected in November and will serve one-year terms . . . Shannon & Luchs has named Dan Demeria director of its Virginia new homes sales division . . . Lawrence B. Sween has been elected president of HBW Realty, Inc. . . . Dianna Wills, Stephen I. Friedman and Francis R. Scheffenacker have been promoted to senior property managers at Dreyfuss Brothers Inc. . . . Home Owners Warranty Corp. has named Beth Kravetz as staff attorney . . . Centennial Development Corp. has announced the appointment of David A. Ross as vice president, director of marketing . . . Kathy Felling has been named branch manager of Merrill Lynch Realty's Springfield office . . . Century 21 Cedarhurst, Inc., has named Al Witt manager of the firm's business brokerage division . . . John P. Fowler has joined Dewberry & Davis as managing principal for transportation and structures.

ON THE MOVE . . . The Fairfax County Board of Supervisors has leased 9,100 square feet of office space at 3959 Pender Dr., Fairfax. Coldwell Banker was the leasing agent.