The Honegger Brothers and the “Système HA”

The Honegger Brothers and the “Système HA” – Casablanca and Geneva: a Prefabricated Concrete Floor System
by Lionel Scherz

The three Honegger brothers—Jean-Jacques, Pierre, and Robert—greatly influenced the urban development of Geneva and the surrounding area, constructing together more than 9,000 homes. They were introduced to architecture by their father, Henri Honegger, in the 1930s. Henri was a property manager and close associate of Maurice Braillard, an influential architect and town planner in Geneva. After collaborating with the architect Louis Vincent, the brothers founded their own firm, Honegger-Frères, venturing into the use of modern construction techniques. While building commissions were low during the economic crisis and the war, they expanded their networks in architect associations such as CIAM (Congrès Internationaux d’Architecture Moderne) and GANG (Groupe d’Architecture Nouvelle à Genève).

After the war, they set up a new office in Geneva in 1947 and began using prefabricated components, at which point an acquaintance invited them to Casablanca. There they founded a company that would operate a patent for constructing cross-ribbed slabs with an easily reusable formwork made of sheet metal. Not satisfied with their first building experience in using this construction method, they refined their idea of rectangular formwork and turned it into prefabricated concrete boxes.

Manufactured in the workshop and installed on site, this system saves a considerable amount of time. The first step is to install wooden props, followed by prefabricated reinforced concrete joists. Between these joists, the concrete caissons are installed. Reinforcement is then placed between the spaces around the caissons and the concrete is poured. Without having to wait for the concrete to dry, the installation of the upper floor can begin.

They improved their system to rationalize construction and material costs as much as possible, and came up with their 60cm-by-60cm caisson system, the “système Honegger-Afrique” or “système HA.” Using this system, they built a number of buildings in parallel in Geneva and Casablanca, before leaving Morocco in 1956 following the country’s independence.

By testing different structural systems in Casablanca and using their own experience in Geneva, they devised a recognizable architectural and constructive language. Economical, adaptable to all contexts and programs, and with a rapid execution speed, their system was a great success. In Geneva, the size and number of their buildings increased considerably until the 1970s, when prefabrication techniques changed and their system did not survive. Around the same time, the three brothers retired and the office passed into the hands of their children. With more than 9,000 homes built, the Honegger brothers have left a lasting mark on the city of Geneva and its inhabitants.