UmbrellasThe “umbrella” was Cubiertas Ala’s standard structure, their “bread and butter” that kept the company in business and allowed Candela the time and resources to design custom-made shells. Candela created umbrellas by joining four straight-edged hypar surfaces. Candela formed a large roof covering by placing several umbrellas side by side. This type of roofing not only offered the advantage of using straight boards for forming, but also was cheaper than all others.
Light enters the space when the umbrellas are tilted to create a sawtooth profile (Rio’s Warehouse) or when the height of the umbrellas in each row is varied (Mercado de Chiclayo), or when the shell is pierced with glass bricks (High Life Textile Factory). With the post Mexican Revolution industrial boom requiring the construction of new market spaces and warehouses, structures of this type provided an opportunity for Candela to build large covered spaces. Within just a few years, he had filled the new industrial zones of Mexico with concrete umbrellas.
In 1952, Candela built his first experimental umbrella. The form had not been constructed previously, although Candela derived the idea from a sketch in an article by a Frenchman named F. Aimond. On the site of another project, Candela constructed a second experimental umbrella in 1953. Candela referred to this experiment “as a lesson to find the optimum rise, which depends on the area covered by the umbrellas. On this simple proportion depends the success in the design of these structures, since the necessary calculations are elementary.” Although Aimond’s sketch stimulated Candela, he realized that more elegant solutions are possible. In Aimond’s sketch, the edge beams are large with a varying height and the column is short and stubby–rational assumptions. Candela’s umbrellas, however, which are also rational, bear a more graceful form, one that was proportioned not only by a builder and engineer but also by an artist.
Candela used folded hypars as an efficient alternative to the common umbrella because they can also cover large areas and the folds break up the expanse of the roof in visually surprising ways. Candela’s first such cantilever was for the entrance to the Lederle Laboratories in Mexico City. Placing together three of these folded hypars he created a fan shape which seemed to him to be “more or less obvious”. As a next step, he undertook in 1956 the band shell at Social Security’s new housing project in Santa Fe, Mexico City. Finally in 1968 he built the subway station roof of La Candelaria in Mexico City, comprised of rectangular umbrellas, formed by folded hypars.
This evolution of umbrellas shows that Candela began with the common form used to design markets and warehouses, progressed to the folded hypar for large cantilevers, and eventually used these folded hypars to create dynamic new forms for umbrella roofs of large spaces such as the Subway Station. Perhaps the most dramatic play of the umbrella was for Church of Our Lady of the Miraculous Medal Church (Iglesia de la Medalla Milagrosa) where the transformation is so dramatic that without careful study one may not notice that the form is derived from the common umbrella.