WASHINGTON (Reuters) - The John F. Kennedy Center for the Performing Arts is planning a $100 million addition, including an outdoor floating stage on the Potomac River, in its first major expansion since it opened in 1971.

Three connected pavilions to house classrooms, rehearsal rooms, lecture space and other facilities were also included in initial plans for the U.S. capital's premier performance space, which were laid out on Tuesday.

The expansion, designed by architect Steven Holl, will take place south of the Center and includes an outdoor video wall. One pavilion will float on the Potomac as an outdoor stage, and public gardens will link the Center with the water.

"Steven's wonderful concept will create a strong visual presence that bolsters the Center's prominence as the national cultural center, while maintaining its unique presence among Washington's iconic landmarks," Kennedy Center Chairman David Rubenstein said in a statement.

The expansion will be paid for from private funds. Rubenstein, a founder of the Carlyle Group private equity firm, is contributing $50 million towards the roughly $100 million cost.

The Center is seeking to raise another $25 million for programming.

Exteriors for the project will include use of Carrara marble, the same Italian marble which clads the site now.

The project is expected to take five years - three years for design and approval by the various agencies and two years for construction.

(Reporting by Ian Simpson; Editing by David Gregorio)