Corporate executives often allow superstition to edge out sound judgment when relocating, the Home Buyers Assistance Corp. reports.

Case records of the compamy, which is based in Westport, Conn., show that major decisions such as whether to buy a particular home depend not always upon such logical considerations as size of mortgage payments, commuting times or the strength of the school system, but rather, in the final moment, upon various psychic messages or the readings of an astrologer.

Real estate brokers can cite instances of corporate managers losing out on the house of their dreams because they refused to negotiate on Friday the 13th, and the firm's relocation counselors have stories in which the purchase of a home was put in sudden jeopardy by nothing more ominous than a black cat crossing the driveway.

Personnel directors and relocation experts can sustain a benign countenance when transferees make odd-sounding requests by keeping in mind that the avoidance of such things as walking under a ladder, having an office on the 13th floor or stepping on a crack in the sidewalk is merely a quirk in our national psyche, the firm suggested.

Moreover, the firm said, not all spooky requests necessarily have spooky meanings. For example, one client who demanded to live under a "black sky" turned out to be a photographic astronomer looking for a view of the stars free of city light. Another client, relocating to New Haven, Conn., asked for a home next to a graveyard. It turned out that all he wanted was to practice his bagpiping where it wouldn't bother the neighbors.

Developer Conrad Cafritz, his brother Carter Cafritz and an associate, Marvin Price, have paid $1 million for David Legum's half interest in Legum & Norman Inc., a 43-year-old D.C. firm that manages 46 community associations and 35 rental properties in D.C., Maryland and Virginia.

"With this partnership, we have formed one of the largest apartment and community association management corporations in the mid-Atlantic states," Conrad Cafritz said.

William P. Norman is now president of Legum & Norman, Richard J. Leeds is executive vice president and Price is secretary.

At the same time, the merged venture has opened L&N Realty Services Inc., with a staff of 40 and offices at 4900 Seminary Rd. in Alexandria and 3313 Connecticut Ave.

Construction is proceeding on the second phase of Metropolitan Square on the site along 15th Street NW where the Rhodes Tavern stood, but the Secret Service still is not happy about it, columnist Jack Anderson reported this week.

The Secret Service tried to block construction of the 130-foot building, because of the potential view overlooking the White House grounds it would provide snipers. In a newsletter for retired Secret Service agents, an agency official said: "The Secret Service objection hasn't changed. But there is only so much we can do. We don't have power over private development."

The city government approved construction of the building, and the decision has been upheld in court rulings.

IN THE BUSINESS . . . Long & Foster, which describes itself as the largest-volume real estate firm in the Baltimore-Washington area, says it is the first company in the region to pass the $3 billion sales mark in a year, with $3.4 billion in sales last year on 30,594 units sold. The sales figure is up $1 billion over 1984 . . . The total value of building permits issued in the first half of 1985 in the nation's 200 largest cities totaled $26.9 billion, up 5.3 percent over the same period a year earlier, according to Dun & Bradstreet Corp. . . . Total construction contracts for the District totaled $964.13 million last year, up 22 percent over 1984, according to the F.W. Dodge Division of McGraw-Hill Information Systems Co. . . . Owens-Corning Fiberglas Corp. of Toledo and Green Tree Acceptance Inc. of St. Paul, Minn., have started a new financing option to help mobile home buyers qualify for bigger loans. Called "energy qualified financing," the plan is based on the idea that those who buy Owens-Corning's homes with energy-saving components will cut their monthly heating and cooling costs and thus will have more spendable cash for a bigger monthly mortgage. Through the financing plan on such homes, Green Tree will increase the typical housing debt-to-income ratio of buyers from 35 to 40 percent and cut the mortgage interest rate by one-quarter of a percent . . . The Virginia Association of Realtors reports that 68,063 existing homes were sold last year, the best year in the five years that statistics have been kept. The 23,000-member organization has installed Joseph K. Funkhouser II of Harrisonburg as president . . . InterGate Co. has announced plans to build a 280-room hotel at Loudoun Gateway Center, a 180-acre mixed-use commercial complex at the intersection of Rtes. 28 and 606 near Washington Dulles International Airport. It will be managed by Registry Hotel Corp. of Dallas . . . Interstate General Corp. of San Juan has purchased the 150-acre south section of the Montclair development in Prince William County and plans to build 920 units by 1990. The firm has been involved in the development of Montclair for more than a year . . . MUSCLE, a nonprofit Washington housing developer, has bought the vacant property at 1106 Columbia Rd. NW for $80,000 from National Bank of Washington and will develop it as a limited equity cooperative with 10 one-bedroom and 10 two-bedroom units. Rehabilitation work starts in March, with completion set for December . . . Gerald J. Rohe, home improvement manager of the Sears Roebuck store at Hunt Valley, has been elected president of the Maryland Improvement Contractors Association . . . The American Gas Association has developed GasTech, a personal computer program costing $100 which can determine the annual energy usage and operating costs for natural gas heating and electric heat pump systems . . . Richard K. Juergens Jr., president of Frank S. Phillips Mortgage Co., has been elected president of the Mortgage Bankers Association of Washington . . . Roberts & Lloyd, a Vienna realty firm, has bought two offices of Ambassador Real Estate of America Inc. in Manassas . . . George Hyman Construction Co., with a low bid of $38.94 million, has won the construction contract over five other firms to build the new Canadian Embassy at 501 Pennsylvania Ave. NW . . . Westin Hotel, a nine-story, 416-room facility, has opened at 2401 M St. NW. It includes a banquet hall that can seat 500 persons, a 185-seat auditorium, two restaurants and a lobby lounge . . . Donohoe Construction Co. has started work on a four-story office building 4900 Yuma St. NW that is owned by W. C. & A. N. Miller Development Co. . . . The Suburban Maryland Building Industry Association, through its charitable subsidiary corporation, the OTS Foundation, has given a one-acre site worth $50,000 in the St. Charles Industrial Park in Waldorf to the Tri County Youth Services Bureau . . . John B. Murgolo, a property manager for Aldon Management Corp., has become president of the Property Management Association of Metropolitan Washington . . . The Beacon, once a boarded apartment building at Calvert Street and Adams Mill Road NW in Adams-Morgan, has been rehabilitated by Crescent Construction Co. into a 49-unit condominium.

PERSONNEL FILE . . . Leonard C. Whitecar, formerly senior vice president of Coldwell Banker in the Washington area, has been named president of Howell Properties of Virginia Inc. . . . Walker & Dunlop, a realty firm, has named two new vice presidents -- Wayne A. Frahn for commercial leasing and Robert W. McComis for commercial mortgages . . . Mark A. Stefanek has been named vice president of Western Development Corp. and is responsible for the analysis of management reports, while Steven A. Grigg has been named senior vice president for mixed-use projects at the same firm . . . Lee Sammis Associates Inc. has named two new vice presidents -- Mark Hassinger for development and John Tribble for planning and operations.