Reptile Laboratory, NE Pavilion, second floor, with fireproof ceiling, ca. 1903 Washington, D.C. architectural firm Cluss & Schulze designed the ground floor of the Arts and Industries Building to be safe, solid and structurally sound. The floors of the towers, pavilions, and annexes were built with segmental brick arches sprung between rolled iron beams – a fireproofing technique frequently used by Adolf Cluss in his building designs. This new “slab on grade” technology eliminated the enclosed joist spaces under floors, where fires often originated. It also allowed for installation of extremely heavy industrial exhibits, like locomotives. Cluss specified hydraulic cement concrete for the museum exhibition area and basement floors. This strong, fast-setting, waterproof material was also used in the building’s foundations.

Cluss originally intended for the concrete floors in the halls to be left exposed and covered with asphalt; this decision was met with disapproval within Congress. Maine Senator James G. Blaine (1830-1893) was quoted in 1880 as saying, “I think that [to leave the floors exposed] would be a great disfigurement to a building which will be greatly visited, which will be an object and center of interest to all the visitors to Washington and to the whole people of the country.” Congress subsequently appropriated an additional $26,000 to the Smithsonian Institution “for flooring of marble and encaustic tiles in the large halls of the National Museum building.”