method of building with concrete in which individual cells, or rooms, are set horizontally and vertically together to create an overall structural frame. Because the main weight of the building is carried through the cross walls, they must be sufficiently thick to carry their own weight as well as loads from above, and so the potential height of a structure built in this manner is limited. The most common application is in low apartment flats and similar buildings having walls and floors formed by reinforced concrete slabs.

Beginning in the late 1880s a number of large structures were built with concrete walls and floors made of precast slabs or poured as monolithic sections. The best-known example is the Hotel Ponce de Leon, St. Augustine, Fla. (1886–88). Construction with plain concrete, as used there, was soon replaced by building with reinforced concrete, and box frame construction was superseded by an open frame system in which the walls have no load-bearing function.