Joining a trend toward major expansions, the Frick Collection, known for its intimate, jewel-box galleries, will announce on Tuesday plans for a new six-story wing that will increase its exhibition space, open private upstairs rooms, and offer views of Central Park from a new roof garden on East 70th Street.

With its proposal, the Frick joins a roster of museums across the country that are enlarging, a sign perhaps of increased competition for the cultural spotlight, as well as a rebound in fund-raising since the dark days of the economic downturn.