The Guastavino tile arch system is a version of Catalan vault introduced to the United States in 1885 by Spanish architect and builder Rafael Guastavino (1842–1908).^[1] It was patented in the United States by Guastavino in 1892.^[2]

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 (corbelling), or perpendicular to the curve (as in Roman vaulting). This is known as timbrel vaulting, because of supposed likeness to the skin of a timbrel or tambourine. It is also called Catalan vaulting (though Guastavino did not use this term) and "compression-only thin-tile vaulting".^[3]

Guastavino tile is found in some of the most prominent Beaux-Arts structures in New York and Massachusetts, as well as in major buildings across the United States.^[4] In New York City, these include the Grand Central Oyster Bar & Restaurant and the remnants of the Della Robbia Bar at the former Vanderbilt Hotel at 4 Park Avenue.^[5] It is also found in some non-Beaux-Arts structures such as the crossing of the Cathedral of St. John the Divine.^[6]

The Guastavino terracotta tiles are standardized, less than 1 inch (25 mm) thick, and about 6 by 12 inches (150 by 300 mm) 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. Supporting formwork was still required for structural arches which established a framework for the ceiling. The large openings framed by the support arches were then filled in with thin Guastavino tiles fabricated into domed surfaces. Each ceiling 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.

• Construction of Guastavino tile arches in McKim Building at Boston Public Library (1889)
• 
  Steel I-beams framing the building provide structural support for Guastavino tile arches
• 
  Formwork for shallow tile arches along Boylston Street
• 
  Rafael Guastavino inspecting recently laid tile arch along Boylston Street
• 
  Workmen filling in tile vault domed ceilings
• 
  Four completed tile domes along Boylston Street
• 
  Tile arches along Dartmouth Street
• 
  Tile arches and buttresses in entrance hall
• 
  Closeup of completed tile arches and column in entrance hall
• 
  Guastavino tile vaults are strong enough to support the flooring above.
• 
  Completed tile domed ceiling in basement
• 
  Load testing of tile arches

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.^[4]

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.^[7]

Ochsendorf also curated Palaces for the People, an exhibition featuring the history and legacy of Guastavino which was 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 later 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,^[1] and an online exhibition coordinated with the traveling exhibits.^[8]

In addition, Ochsendorf directs the Guastavino Project at MIT, which researches and maintains the Guastavino.net online archive of related materials.^[9]

The Guastavino company was headquartered in Woburn, Massachusetts, in a building of their own design which still stands.^[10] The records and drawings of the Guastavino Fireproof Construction Company are preserved by the Department of Drawings & Archives in the Avery Architectural and Fine Arts Library at Columbia University in New York City.

• Glazed architectural terra-cotta
• List of architectural vaults
• First Church of Christ, Scientist (Cambridge, Massachusetts)
• Ed Koch Queensboro Bridge
• Basilica of St. Lawrence, Asheville
• Biltmore Estate
• Grant's Tomb
• Grand Central Oyster Bar & Restaurant

• Ochsendorf, John; photographs by Michael Freeman (2010). Guastavino Vaulting: The Art of Structural Tile. New York: Princeton Architectural Press. ISBN 978-1568987415.{{cite book}}: CS1 maint: multiple names: authors list (link)

Wikimedia Commons has media related to Guastavino tile.

• PalacesForThePeople.com^[usurped] global database of Guastavino sites with photos. Created as a companion to a museum exhibition that traveled to three American museums, 2012–2014.
• Guastavino.net: documenting Guastavino's work in the Boston area. This page provides copies of writings and patents by the Guastavinos as well.
• Rafaelguastavino.com: documenting Guastavino's work in New York City
• "CONSTRUCTION OF A VAULT", Massachusetts Institute of Technology (shows method of construction)