Guastavino vaulting is a technique for constructing robust, self-supporting arches and architectural vaults using interlocking terracotta tiles and layers of mortar to form a thin skin, with the tiles following the curve of the roof as opposed to horizontally, or perpendicular to the curve. This is known as timbrel vaulting, because of supposed likeness to the skin of a timbrel or tambourine. It is also called Catalan vaulting and "compression-only thin-tile vaulting". Guastavino tile is found in some of New York’s most prominent Beaux-Arts structures and in major buildings across the United States. It is also found in some non-Beaux-Arts structures such as the crossing of the Cathedral of St. John the Divine.
Construction
The Guastavino terracotta tiles are standardized, less than an inch thick, and approximately by across. They are usually set in three herringbone-pattern courses with a sandwich of thin layers of Portland cement. Unlike heavier stone construction, these tile domes could be built without centering. Each tile was cantilevered out over the open space, relying only on the quick drying cements developed by the company. Akoustolith, a special sound absorbing tile, was one of several trade names used by Guastavino.
Significance
Guastavino tile has both structural and aesthetic significance. Structurally, the timbrel vault was based on traditional vernacular vaulting techniques already very familiar to Mediterranean architects, but not well known in America. Terracotta free-span timbrel vaults were far more economical and structurally resilient than the ancient Roman vaulting alternatives. Guastavino wrote extensively about his system of "Cohesive Construction". As the name suggests, he believed that these timbrel vaults represented an innovation in structural engineering. The tile system provided solutions that were impossible with traditional masonry arches and vaults. Subsequent research has shown the timbrel vault is simply a masonry vault, much less thick than traditional arches, that produces less horizontal thrust due to its lighter weight. This permits flatter arch profiles, which would produce unacceptable horizontal thrust if constructed in thicker, heavier masonry.
Exhibitions
In 2012, a group of students under supervision of MIT professor John Ochsendorf built a full-scale reproduction of a small Guastavino vault. The resulting structure was exhibited, as well as a time lapse video documenting the construction process. Ochsendorf also curated an exhibition Palaces for the People, featuring the history and legacy of Guastavino, which premiered in September 2012 at the Boston Public Library, Rafael Guastavino's first major architectural work in America. The exhibition then traveled to the National Building Museum in Washington DC, and an expanded version appeared at the Museum of the City of New York. Ochsendorf, a winner of the Macarthur Foundation "genius grant", also wrote the book-length color-illustrated monograph Guastavino vaulting : the art of structural tile, and an online exhibition coordinated with the traveling exhibits. In addition, Ochsendorf directs the Guastavino Project at MIT, which researches and maintains the Guastavino.net online archive of related materials.
