The total value of construction contracts signed in June in the Washington area jumped 77 percent, compared with June 1978, the F.W. Dodge Division of McGraw-Hill reported. Nonresidential contracts rose from $63 million to $157.2 million and residential construction increased 28 percent, to $110.6 million. Nonresidential construction was up 31 percent for the first half, while residential construction fell 4 percent during the six months.

The last of the condominium units in the Parc East high-rise in Alexandria have been sold, International Developers Inc. announced. The 15-story, 283-unit complex is on Martha Custis Drive and is next to Parkfairfax, a garden apartment condominium project of IDI. Prices at Parc East ranged from $17,800 to $47,900.

Resale prices in Montgomery County leveled off during June after a steep rise in prices during the first five months, reports real estate consultant Alfred W. Jarchow. Although the second quarter ended with a 4.8 percent gain, it was a smaller gain than that of the same period last year.

A free seminar on investing in real estate will be held at 7:30 p.m. Thursday on the concourse level of Mazza Gallerie, Wisconsin and Western avenues NW, by the Dean Witter Reynolds investment firm. Owning and renting, condominiums and co-ops, financing a loan, cash flow, tax breaks and refinancing will be discussed. For reservations, call 966-5776.

The Homecrest House, a five-story, 135-unit facility for senior citizens, sponsored by B'nai B'rith Housing Foundation, opened this month on Homecrest Road in Silver Spring. Financed and subsidized by the Department of Housing and Urban Development, the apartment house is accepting applications for those meeting minimum income requirements of $14,400 for couples or $11,600 for individuals.

A two-day course on managing condominiums will be held at the International Inn Sept. 8 and 9 by the Institute of Real Estate Management. The seminar, which costs $115, covers condominium-related laws, insurance, budgets and contracts. Write IREM, 430 N. Michigan Ave., Chicago, Ill. 60611, for information.

A $2 million contract was signed by Winchester Homes, Inc., a subsidiary of Weyerhaeuser Real Estate Co., to purchase lots for single-family homes in the Newbridge Country Club area of Mitchellville, Md. The subdivision will have six house models ready this fall. Prices will start in the low $90,000s.

Albert L. Jones, Sr. was named to his fourth, one-year term as chairman of the Maryland Real Estate Commission. Jones, who has operated his own brokerage and appraisal firm in Baltimore Country for more than 30 years, will oversee real estate licensing and regulations in the state.

Crestwood Village, a 1,400-unit community about to open in Frederick, Md., will be managed by Lawrence Gaffigan, formerly of Grady Management, Inc.

Oxford Development Corp. has begun building Claiborne Place, a 13-story, 174-unit project for senior citizens near Annapolis. Financed by the Community Development Administration, the project is located on Riva Road near Forest Drive and is planned to be completed in a about a year.

Harold A. Glazer has been named president of Ryland Mortgage Co., a new subsidiary of Ryland Group, Inc. Glazer, who was senior vice president of Carruth Mortgage Corp. for three years, will develop branch facilities for the Columbia, Md., home-building company.

The 75-room National Hotel at 1808 I St. NW has been sold by National Hotel Co., Inc. for more than $1.1 million. It was the fourth time the hotel has been sold. The new owners, Three Jays Associates, plan to add a drycleaning outlet on the first floor of the hotel.

David G. Fox, a Dallas homebuilder, has been elected chairman of the National Association of Home Builder-affiliated Home Owners Warranty Corp.