Guastavino tile

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

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 its 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".

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. 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. It is also found in some non-Beaux-Arts structures such as the crossing of the Cathedral of St. John the Divine.

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 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.

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.

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.