Concrete Shell Roofs

Concrete shell roofs are based on a mathematical formula designed by two German engineers in the 1920s. The first concrete shell roof was actually constructed for the Jena Planetarium in 1924. The concrete shell roof was crafted by spreading a thin layer of concrete over a frame of reinforcement bars and trusses. After that, the success and use of the shell roof grew. By the 1930s, engineers were designing concrete shell roofs in Spain, Italy and France. They were as practical as they were aesthetically pleasing. Designers tweaked the appearance and design to create their own signature look. It was not until 1934 that the first concrete shell roof was built in the United States. The Brook Hill Farm Dairy Pavilion became American's first exposure to this roofing style at the Century of Progress International Exposition in Chicago, Illinois. Ironically, one of the engineers for the European-based company who designed the first concrete shell roof, moved to the United States and convinced an architectural firm to purchase the rights to the design for use in North America.

The cross-cultural sharing of ideas and architecture was an example of how small the world truly is. After the Brook Hill Farm Dairy Pavilion, other concrete shell roofs popped up in metropolitan New York City at the Hayden Planetarium at the American Museum of Natural History. By 1936, the Hershey Sports Arena in Hershey, Pennsylvania became well known not for its chocolate, but for having the largest concrete shell roof in the world. The popularity of this style of roof continued to grow and soon became the focus of military interest.

The military was especially interested in the easy of construction and durability of such structures. They saw the practical application for this style of roof in airplane hangars, factories for war efforts and warehouses to store supplies. Many old military installations still show the remnants of old concrete shell roof structures. By the 1950s, designers were using concrete shell roofs to create everything from commercial airline hangars to museums. The Sydney Opera House in Sydney, Australia is an example of one of the most famous concrete shell roof structures. The cost of construction was astronomical, but the durability of the roof has been proven time and again. In recent times, concrete shell roofs have lost some of their appeal, as the cost of steel has risen and the advocates for such a roofing style have dwindled. While some architects still contend that the concrete shell roof offers a wide range of aesthetic and structural possibilities, most resort to using traditional roofing. Whether this style of roof comes back into the mainstream remains to be seen.