Construction contracts signed in August for future work in the Washington metropolitan area were down 32 percent in value from a year earlier. the F. W. Dodge Division of McGraw-Hill Information System Co. reported. Total contracts signed were down from $216.1 million to $147.9 million. For the year to date, the value was down 23 percent for all construction in the area. The biggest drop was for nonresidential work in the District, which was off by 41 percent.

James W. Todd, president of three Mobil Land Development Corp. real estate companies based in Reston, this week was named president of the corporation's eastern division. This expands his responsibility from two Washington projects. Reston and Colonial Village, to three other communities north of Atlanta.

General Electric Mortgage Insurance Corp., a new private mortgage insurance corporation, has been approved for licensing in Virginia and the District of Columbia, the parent company, General Electric Credit Corp., announced. The firm provides mortgage insurance to lenders, insuring them against default on home mortgages.

The third house adapted for use by handicapped residents has been sold in St. Charles, Md., by Oakridge Housing Corp. The $70,000-range house was purchased by Spring Dell Center, an organiation that plans to use it as a group home for adults. Among the special features are wide hallways, hand rails and ramps.