Kaiser Permanente, the nation's oldest health maintenance plan, broke ground Saturday for a health care center in Kensington to replace an existing center that was so crowded it overflowed into a second building.

The 85,000-square-foot building will go up at 10810 Connecticut Ave., near the intersection of Connecticut Avenue and University Boulevard. It will contain 40 physicians' offices in addition to clinical and office space. Medical services available at the new building will include primary care and many specialty services such as orthopedics, cardiology, neurology, opthalmology, urology, radiology and physical therapy. There also will be a pharmacy and an after-hours center in the building.

The Kaiser health plan was formed in the 1930s to provide health care for employes of Kaiser Industrial and was opened to the public in 1945. The plan's members now number 5 million across the country. There are 11 Kaiser centers in the area. The facility about to be built will be the third local center owned and built by the company. The company had outgrown its leased facility, said Jenke, and had a stable local membership.

Cannon/Faulkner of the District is the architect and engineer for the project. Its affiliate, Professional Construction Managers, will oversee building construction.

The new center will replace the office building that Kaiser leases at 10500 Summit Ave. The company had leased an additional 17,000 square feet at 10605 Concord St. to handle overflow.

In other developments in commercial realty: Kay Jewelers credit center leased 10,000 square feet at Airport Square, Willard Road and Rte. 28, Chantilly, from Dickinson-Heffner.

The Federal Savings and Loan Insurance Corp. (FSLIC) leased 8,937 square feet at 1730 Rhode Island Ave. NW.

SEED Software Corp., a manufacturer of computer software, leased 8,722 square feet at One Beltway Center, Rte. 1 and I-495, Alexandria, from Edwin R. Carr & Associates.

The American Electronics Association leased 8,602 square feet at 1225 I St. NW from the John Akridge Co.

Frederic R. Harris, an engineering company headquartered in New York City, leased 8,347 square feet at 2750 Prosperity Ave., Merrifield.