The 290-unit Crestview Apartments, at Whiting and Van Dorn streets in Alexandria, is being sold to commerical broker Allan B. Hudson Jr. and W. Howard Rooks, president of Mount Vernon Realty, who plan to rehabilitate it and convert it to condominium ownership. The 25-building complex was built in the mid-1960s and needs "corrective work on mechanical and electrical systems," Hudson said in a letter to tenants.

Mortgage money for qualified tenants of 22 Montgomery County apartment buildings being converted to condominium ownership is still available through the lower-interest mortgage program of the county's Housing Opportunities Commission, a spokeswoman said this week. The 12 percent loans, backed by tax-exempt bonds issued by the commission to help tenants in converted buildings, have gone to five buyers thus far. Money for more than 30 additional loans is still in the fund, the spokeswoman said. Income limits range from $24,000 to $33,000; tenants may buy any of the 22 buildings, where property reports were filed between Jan. 1, 1979, and April 8, 1981. Information is available at 565-5775.

Sales of apartments at The Albemorle Condominium, 1830 17th St. NW have begun, according to an announcement from the sales agent, Brenneman Associates, Inc. Prices at the recently renovated turn-of-the-century building range from $80,000 to $184,000.

Port City Builders is renovating a group of 17 garden apartments for sale on Russell Road near the King Street Metro station. Prices at the Station Street project start in the low $70,000s, the builder said.

A three-week course in home building for people interested in building their own houses will begin May 2 under the sponsorship of The Foundation Home Building Institute of Manassas. It costs $375 for individuals and $650 for couples. For information, call 703-791-5382.

The Apartment and Office Building Association of Metropolitan Washington will sponsor an all-day seminar on apartment management and maintenance next Thursday at the National 4-H Center in Chevy Chase. For information, call 293-3995.