They’re fast to build, use low-cost and low-carbon materials, require only small teams and can last for centuries. So why aren’t timbrel vaults in greater use?
This article was originally published in the May 2025 issue of create with the headline “Timbrel vaults”.
For more than 2000 years, constructing large spans called for vaults or domes. Beginning with the classic Roman arch, curved forms were essential for large spans, and, in the centuries since, builders developed a dizzying array of structural vaults.
One of them is the timbrel vault. Believed to have been developed in the 14th century in Europe, these masonry vaults were used in everything from Spanish cathedrals to some of the most iconic American architecture, including Grand Central Station in New York.
The basis of timbrel vaults is thin, often hollow bricks, also known as tiles, usually about five cm thick. The first course is laid, usually without formwork, using fast-setting gypsum plaster to create a self-supporting arch. As little as one or two additional interlocking courses, are then laid on top and set with lime or cement mortar.

The result is a strong, slender and lightweight arch that seems to defy physics. With masonry’s strength in compression, many timbrel vaults have a span-to-thickness ratio of 200:1, about half the relative thickness of an eggshell. This lightweight approach also means smaller supports and buttresses.
As well as reducing costs, the absence of formwork greatly reduces material inputs, speeds up construction and means a single small crew is all that’s needed to build the spans.

Large spans are possible, such as the 33-m span of New York’s St John the Divine cathedral.
Why they disappeared
As with many other vaults, timbrel vaulting began falling from favour in the first decades of the 20th century, as reinforced concrete grew in reputation, ease and affordability.
But this is not to say that reinforced concrete construction techniques necessarily have performance benefits over timbrel vaulting, said António Sousa Gago, Associate Professor in Civil Engineering at Lisbon’s Instituto Superior Técnico, who has extensively studied the technique.
“To do a reinforced concrete slab you need at least three teams: one to do the formwork, another to put the steel in, another to put the concrete in,” he said. “With timbrel vaulting, you are able to do it with just one team, working very fast.”
The technique’s decline was likely more driven by trends. “I think people wanted to have a modern technique.”

A modern approach
In recent years, however, a number of forward-thinking engineers and architects have revisited timbrel vaults with modern sensibilities, materials and tools.
The movement was in large part sparked by the efforts of Spain’s Julio Jesus Palomino and Manuel Fortea, but has since grown to span many countries. For instance, Switzerland’s BLOCK Research Group has deployed custom modelling software to design freeform vaults (see image above), while US engineering and architecture firm SOM has explored ways to redress a significant weakness of timbrel vaults – their vulnerability to lateral forces, such as those experienced in earthquakes.
Their engineers found applying geogrid, a polymer mesh usually used in ground reinforcements, to timbrel vaults would dramatically improve performance against lateral forces.
There has also been widespread interest in popularising the technique as a way of enabling more affordable construction in the developing world, thanks to the low cost of the building materials, the absence of specialised equipment and the teachability of the basic technique.
For example, in 2009, Peter Rich Architects built the Mapungubwe Interpretation Centre with extensive use of timbrel vaults, training local people in the manufacture of the tiles and the construction technique. These skills have since been put to use in housing construction nearby.

Future paths
In developed nations, Gago said, there are often greater obstacles to redeploying the technique.
“You cannot use the same tools and the same codes as used in concrete or steel,” he said. “Instead of a linear elastic analysis, you must have a nonlinear elastic analysis. That can be a problem because it is quite different to what many engineers are used to.”
To remedy this, Gago is hoping to pull together the leading practitioners and researchers to develop an international construction code for timbrel vaults, giving engineers, architects and builders the calculations and rules they need to have confidence in the technique.