Prefabrication experiments - 64 - Monolithic thin shell domes

The relationship between industrialisation and building was founded on three principles: repetition, efficiency and quantity. The search for efficiency and innovation was weighed against traditional wood or masonry construction. Although industrialization offered speed and new methods, building culture related and still relates to slowly evolving trades, materials and methods. In order to rival traditional techniques and crafts, industrialization aimed to lower costs either by repeating processes, components and assemblies, by producing progressive experiments or by challenging traditional shapes and architectural types.

The classic dome or circular arch structure prompted experiments in almost every material: pre-cut geodesic skeletal or panel structures, fold-up domes, assembled shell segments and sprayed domes.  The dome’s legacy as a robust form resistant structure was conducive to prefabrication; it could be engineered simply. Wallace Neff’s bubble houses are an example of domes used for housing. Neff’s Domes were cast over inflatable plastic moulds known as bubbles. Each dome could be a single housing unit or juxtaposed to form an aggregated cellular housing structure. The inflatable moulds were light, transportable, generated no waste and required few man-hours to erect.

Neff’s techniques were further developed and commercialized by David South.  South’s monolithic thin shell dome structures employed and some still employ an inflatable polymer-based form or shape. Similar to the earlier Neff experiments, air pressure keeps the dome’s shape in tension during the moulding or spraying process. The domes are produced by spraying either thermosetting resins, light air-entrained concrete, polyurethane expanding foam or both a urethane layer and a concrete layer. The thin shell hardens and cures to a strong thermal resistant half-sphere. This type of monocoque dome employed one trade and simplified the complex procurement process that came along with building a traditional structure.

The interior surface could be finished with a cement-based coating or painted while the exterior surface of the dome could be covered with a UV protector or also finished with a cement-based coating. Available in multiple diameters, the domes were built in any context and for a diversity of uses. The dome has crossed eras and has proven to be a highly flexible structural system, however it has had less success as housing. The prismatic shapes of classical, medieval and modern architecture have anchored an aesthetic for dwelling that is difficult to sway from.

Left : Wallace Neff's bubble domes ; Right David South's patent drawings