Prefabrication experiments - 432 - XL(slabs) - ZUP at Bayonne

 

Interwar years in France intensified dwelling as well as urban hygiene crises. An estimated 5 million units lacked running water and basic services. The devastating damage to hundreds of thousands of buildings during the second world war exacerbated this need for quality housing. In response, centralized policy sanctioned new dense developments all over the country under the label, ZUP - Zones à urbaniser à prioriser (liberally translated to Priority Zones to Urbanize). Projects and their promoters which provided a minimum of 500 units in tightly packed edifices required affordable and efficient construction methods to be deployed at scale. 

 

The slab block was adopted by an industry increasingly articulated to reinforced concrete; a material the country's inventors (Hennebique, Monier, Lambot and many others) had been central in cultivating. Beyond the material's advantages in terms of fireproofing and strength, it also lent itself to all types of prefabrication strategies. Marcel Breuers' flagship ZUP design for 1100 units at Sainte-Croix/Saint-Esprit, in the small community of Bayonnne explored precast concrete construction to propose a formidable building system. Designed and built from 1963 -1967, the master plan included dwellings and several services including a school and shopping center.  

 

Using a factory cast wall panel system inspired by the Camus System (also invented in France), Bayonne buildings were arranged as a cellular hive of flats and simply covered in a precast thick panel. The basic structural strategy of walls and slabs at Bayonne was cast on site using a tunnel form system:  a moveable prismatic formwork that defines a cell with a horizontal plane supported by two vertical planes. The tunnel forms are usually made of steel. Once the concrete is cast, the steel framed-moulds slide out and are reused on subsequent floor plates. 

 

The heavy wall panels’ architectural treatment at Bayonne showcase Breurer's talent and understanding of prefabrication's potential to create dynamic façades using mass manufactured components. The panels were cast as a thick solar shading device with built-in furniture and window openings. A mirrored pattern was repeated every two stories creating a textile like façade; the project's simple renderings illustrate how architectural regularity defined a coherent material field. 

Rendering of the Bayonne master plan