The Montgomery County Planning Board has analyzed the I-270 corridor area north of Rockville and concluded that the area has the potential in the next 4 years for more than 3 million square feet of new office and research-development space, and more than 450,000 square feet of warehouse space, plus 300,000 square feet of new retail space. The study also forsees a potential demand for 13,000 new housing units, of which 3,000 would be rental.

Realtors Anne Charles and Drexanne Evans, who live and work in the Greater Cincinnati area, were in Washington last week to conduct interviews with top-producing area realty agents. They are visiting several cities in order to "find the common denominators in our industry's best sales persons." Evans is president of Drexells Inc., 8756, E. State Route 3-22 in Clarksville, Ohio., 45113. Charles is a consultant with Drexells.

Anthony Reynolds, a District appraiser, has been named chairman of the national external affairs committee of the American Institute of Real Estate Appraisers, which this year is headed by William S. Harps of Washington.

The regional group of the Farm and Land Institute of the National Association of Realtors is sponsoring meetings and a course on presenting properties. The course will be given Feb. 10 and 11 at the center for adult education at the University of Maryland. Advance registration is required. Call Pierre Vining (301) 855-8552. He lives in Dunkirk, Md.

Paul B. O'Connell of Willow Grove, Pa., was recently elected president of the American Society of Home Inspectors Inc., which recently held a conference here. He success John J. Heyn of Towson, Md. New officers include Claxton Walker of Potomac.

The area chapter of the American Society of Appraisers will meet Feb. 3 at the officers club at Fort McNair, where appraiser Kenneth Martin of New York City will discuss recertification.

Angel F. Clarens and Jan M. Widmore have open an architectural office at 3065 M St. NW. Both formerely were with other architectural firms in this area.

A seminar on sales opportunities in securities and investments, business counseling, real estate and insurance will be held Jan. 31 at 9:00 a.m. at the Bethesda Marriott and at 1:30 p.m. at the Tysons Corner Holiday Inn. Admission is free. The sponsors are Ferris & Co., Shannon and Luchs Realtors, General Business Services and Wallace/Lovett Associates. Information is available by calling 897-8000.

Randall H. Hagner & Co. and Franklin Mortgage & Investment Co. co-operated in placement of a $7.5 million mortgage on the Jefferson building at 1225 19th St. NW. The eight-story building, on which a renovation program is nearly completed, is owned by a partnership that includes George Nolin, Franklyn de Marco Jr. and Thornton W. Owen Jr.