The Scarborough Corp. has begun construction at Fair Oaks Estates, a subdivision of detached houses on Rte. 50 a mile west of the new Fair Oaks Mall in Fairfax County. The New Jersey-based firm also will build this year in the Lake Ridge and Montclair subdivisions in Prince William County.

A 163-page booklet called Budget Guidelines, a Practical Guide for Preparing Homeowners Association Budgets, a avilable for $38.19 from the Wyndham Co. Inc. 25283 Cabot Rd. Suite 101, Laguna Hills, Calif. 92653.

Banco Mortgage Co., a mortgage loan company based in Minneapolis, will move from Kensington next month to 6101 Executive Blvd., Rockville. Joseph W. Rogers Jr. is manager.

Long & Foster real estate company reports that it sold $130 million in houses and condominiums last year, compared with $102 million in 1979.

The Alexandria Development Co., a partnership that includes Pat Blew and Madison House Investors, is converting the 15-story Madison House in the Landmark area of Alexandria to condominum ownership. The 283-unit apartment building has been renamed Pavilion on the Park Discount purchase prices to tenants begin at $34,100 for efficiency units. Two-bedroom units are priced up to $84,100.

Douglas R. Fahl recently was named Man of 1980 by the Northern Virginia Builders Association. Cecil Boyer Jr. has been succeeded as NVBA president by Leonard Abel.

Robert Graham has been named sales manager for the Panorama Real Estate office in Vienna. A former naval officer, Graham recently was with the Panorama office in McLean.

C. Edwin Becraft has been elected president of the area chapter of the Associated Builders and Contractors. He succeeded Richard W. Hottel. A native of Olney, Becraft now is vice president of Glen Construction Co. Inc. of Rockville.

Pat Truchio has been named property manager with J. Edwards Real Estate Co. in Alexandria.

Ginseppe Cecchi, area builder and developer, will be speaker Monday evening when the Northern Virginia Apartment Association meets at the Westpark-Rosslyn Hotel. Cecchi is president of International Developers Inc., which built and sold the large Rotonda condo apartment complex in Tysons Corner.

Consumer affairs will be the topic of a seminar-workshop to be held at 4:30 p.m., Jan. 29, at the Bethesda-Marriott by the Suburban Maryland Home Builders Association. After the seminar, the SMHBA will have a dinner meeting at the same hotel, where Maryland comptroller Louis Goldstein will be the speaker. Robert L. Mitchell will be installed to serve a second term as prsident of the association.

Norman V. Watson, a former assistant secretary of Housing and Urban Development, will speak at the Jan. 27 luncheon meeting of the National Housing Conference at the National Housing Center, 15th and M streets NW.