Make: Online : Lost Knowledge: Timbrel vaulting

The twice-monthly Lost Knowledge column explores the possible technology of the future in the forgotten ideas of the past (and those just slightly off to the side). Every other Wednesday, we look at retro-tech, "lost" technology, and the make-do, improvised "street tech" of village artisans and tradespeople from around the globe. "Lost Knowledge" was also the theme of MAKE, Volume 17

This week, we look at the largely-lost Medieval art of timbrel vaulting structures and the related, more modern (late 19th century) system of interlocking terracotta tiles which create what are known as Guastavino domes, after their inventor, Rafael Guastavino.

Low-Tech magazine has an excellent introduction to timbrel vaulting and Guastavino domes, called "Tiles as a substitute for steel: the art of the timbrel vault." Here's an excerpt:

The method of timbrel vaulting was developed in the 14th century around the Mediterranean, although its precise origins are unknown. The timbrel vault is also known as a "masonry vault", "Catalan vault", "tiled vault", "laminated vault", "flat vault" and "layered vault" (derived from Spanish, French, Italian and Catalonian descriptions).

A roof of tiles

Timbrel vaulting differs substantially from the Roman method of arch building, which relies on gravity. A Roman vault consists of a single layer of thick, wedge-shaped stones (see below).

The timbrel vault does not rely on gravity but on the adhesion of several layers of overlapping tiles which are woven together with fast-setting mortar. If just one layer of thin tiles was used, the structure would collapse, but adding two or three layers makes the resulting laminated shell almost as strong as reinforced concrete.

The result defies common sense, because a timbrel vault is very thin compared to a Roman vault, while at the same time it is capable of bearing much higher loads. This of course enables wider spans and gentler curves.

The Architecture Department at MIT sponsors the Guastavino Project and Guastavino.net website. Boston was the epicenter for Guastavino domes in North America because the Guastavino Company and Guastavino Company Tile Factory were based there. There were nearly a thousand such buildings throughout the US and some 65 in the Boston area. The website has information and pictures of each of these buildings, maps of their location, info on walking tours of Guastavino buildings around Boston, etc.

In 2005, members of MIT's Guastavino research team traveled to the UK to help build a Guastavino dome for the Pines Calyx conf center near Dover in Kent. The design and construction of the domes drew heavily on Guastavino research done at MIT. Here are some pics of their build.

Structural assessment of Guastavino domes
Architectural engineer Sezer Atamturktur has done an impressive analysis of the structural dynamics and significant features of Guastavino domes: She writes:

Rafael Guastavino refined the technique of erecting thin terra-cotta tile, a thousand year old building system of 'Catalan Vaulting.' His company was involved with more than 1000 buildings in North America between the 1880s and the 1960s. Although Guastavino tile vaulting contributed to many prestigious buildings of that time, the structural behavior of this construction system has received little or almost no attention in the literature. It is the intention of this thesis to study this empirically designed system by using tools of modern engineering: experimental modal analysis, thin elastic shell theory and finite element analysis.

Read her assement doc here.

One interesting project built using a modern interpretation of these domes was the Cuban National Art Schools, an ambitious post-revolutionary (1961-65) plan to create idealized centers for creative/arts education. There were plans for such schools all over Cuba. The first one was never completed and much of the complex is now in ruins. One of the designers behind the project was a student of Antoni Gaudí who did a lot of innovative work with the timbrel vault.

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