Area office and warehouse leasing continues to be so active that owners of some new buildings are including lease clauses to prevent tenants from subleasing to third parties at higher rates.

Industry sources regard this submarket as another indication of continuing demand despite rising prices and the high level of new construction in all parts of this metropolitan area.

Demand for space in Maryland and Virginia recently was surveyed by Spaulding and Slye Corp. It shows a current vacancy factor of only 2.6 percent in Fairfax County in a total new construction market that projects 5 million square feet. The report also showed rates of slightly under $12 a foot for available space in Maryland and Virginia, and of nearly $12 a foot for space under construction in Maryland and nearly $13 for uncompleted space in Virginia.

Continued activity in the leasing market has been documented by the Charles E. Smith Companies' management branch which reports the total preleasing of a 425,000-square-foot building to be completed for October occupancy in Crystal City, where the firm has developed more than 2 million square feet of new office space and hundreds of luxury rental apartments in the past 15 years. Among major tenants in the newest (and largest) Crystal City building will be Booz Allen & Hamilton Inc., Advanced Marine Enterprises EG&G Washington Analytical Services Center, Mantech of New Jersey, Automation Industries Inc. and Advanced Technology Inc.

In another recent major transaction in this area, Castle & Cook Inc. -- an international firm handling food products including Dole pineapple -- has preleased all of the 170,000 square feet in the Greenwood building being completed in Corridor Industrial Park on Routes 1 and 32 east of I-95. The firm formerly had distribution space in Jessup, Md. Developed by Howard Research & Development Corp., the building will be occupied next month.