Felix Candela and His Thin Shell Concrete Structures

A guide to Felix Candela's thin shell concrete structures and the geometry that made them possible.

Felix Candela and His Thin Shell Concrete Structures

Felix Candela proved that concrete, a material most people associate with mass and weight, could be made to soar. Working in Mexico from the late 1940s onward, the Spanish-born architect and engineer built roofs so thin they seem impossible, some only four centimeters deep yet spanning vast halls without a single internal column. His thin shell structures remain among the most elegant demonstrations of how geometry can do the work of bulk.

What a thin shell is

A shell is a curved surface that carries loads primarily through its own form rather than through thickness. Like an eggshell, it gains strength from curvature, distributing forces across the surface as compression and tension instead of bending. This means very little material is needed. Candela understood that if the shape was right, the concrete could be reduced to a skin. The challenge was finding shapes that were both structurally sound and buildable.

The hyperbolic paraboloid

Candela's signature form was the hyperbolic paraboloid, often shortened to hypar. Its great advantage is geometric: although the surface is doubly curved and saddle-shaped, it can be generated entirely from straight lines. That property made formwork dramatically simpler, because the curved shell could be built on straight timber boards laid in ruled patterns. Candela combined and intersected hypars to create umbrellas, vaults and the soaring groined roofs that became his trademark.

Los Manantiales restaurant

His most celebrated work is the Los Manantiales restaurant at Xochimilco, completed in 1958. Eight hypar segments meet to form a fluted, flower-like roof spanning roughly forty meters with an edge thickness of only a few centimeters. The structure needs no internal supports, and the wavy free edges express the flow of forces with almost no visible engineering. It is still studied as a benchmark of how far a shell can be pushed when form and structure are one.

Builder as well as designer

Part of Candela's achievement was that he built his own work through his construction company, Cubiertas Ala. He could test, refine and economize because he controlled the formwork, the pours and the labor. This unity of design and construction is a recurring theme in serious architecture: when the person who shapes the idea also understands how it gets made, the result is usually more honest and more efficient. The same principle drives material-focused practices and fabrication-led studios such as Vertical Custom Supply.

Why his work still matters

Candela's shells were a high point of structural expressionism, and changing economics, especially the cost of labor-intensive formwork, made them rare after the 1960s. Yet his lesson endures: form is structure, and intelligence about geometry can replace brute material. For any architect interested in doing more with less, his thin shells remain a master class in the marriage of engineering and beauty.