JEAN PROUVE’ and prefabrication

Prouvé is a metonymical figure in prefabrication.

His achievements, between the 1930s and 1970s, were developed in line with the search for the new conducted by the Modern Movement, within a concept of the new as a value to be pursued.

This was light prefabrication conceived according to an architectonic distinction (going to the point of schism) between structure and curtain walls, utilizing metal materials (steel and aluminum sheet). In place of the massive organism of the system with bearing walls or the punctual system of a reinforced concrete framework (where the curtain walls emphasize the structural framework), was a system in which structure and curtain walls are independent elements, in functional and figurative terms (building = structure + shell). The shell of the building becomes a sensitive skin designed to protect and contain. The panel is the minimum component of the shell, a self-bearing, modular element, produced entirely in the shop and mounted dry, on the worksite, by skilled laborers, mainly through bolted connections. This was the driving principle that led to uncommon spatial and functional solutions, establishing a new relationship of the building with space and with time, through the introduction of new modes of interchangeability and transformation. The salient innovation is the reversibility of the erection process, which is carried out by jointingjuxtaposition of elements-components. It allows the transformation of a building without demolition, the evolution over time of its constructed form which is no longer fixed and definitive, in a dialectics between the three-dimensional cage of the structure and the two-dimensional surface of the curtain wall panels. Prouvé carried out an incredible series of detailed studies on light facade systems, ceaselessly refined and transformed, frequently patented, the true genealogy of his industrial concepts; a corpus so important as to coincide historically with his crucial contribution to the sector of prefabrication. His achievement was recognized by Frank Lloyd Wright who, upon visiting the Maison du Peuple in 1938, proclaimed Jean Prouvé the inventor of the ‘curtain wall’. This was an attribution that continually enraged the master from Lorraine: “[…] faire une façade legere toute seule c’est idiot […]. J’ai toujours dessiné ensembles […]”, to emphasize the holistic nature of the architectural achievement. The supports, the panels forming the shell, the roofing, all of the framework take shape participating in the equilibrium of the whole, constructing a cohesive organism in which the tension of the balanced parts is mechanism on display.

The building is designed as a pavilion that can be dismantled (a fact which has determined the sad fate of some of Prouvé’s works, lost if not actually stolen) entirely indifferent to the place (the city) and its evolution (history), with which it seeks no association and establishes no relationship apart from that of structural nature (the foundations) or purely functional nature (accessibility); a perfectible équipement urbain in continuous evolution, a prototype subject to constant improtoprovement in its technological installations as well as its spatial and functional features. Prouvé combined the principles of prefabrication with a study of simple building types, distinguished by a specific morphological-structural solution, developing an ‘alphabet of structures’ that brings together different building types, an underlying theme that unites furniture-houses-skyscrapers (considering, for example, the central-core principle applied to the Casa Alba or the Nobel Tower). The axial portico type, the crutch type, the shell type, the vault type, the central-core type, were developed in studies, prototypes and realizations. These architectural ideas derived from reflections on the static-structural system, on the functional layout, with spatial and figurative invention based on the conditions necessary for constructing a building, under the aegis of ‘necessity’, ‘economy’ and ‘lightness’. For the variety of the subjects dealt with and the strictness of his methodological approach, for his commitment, financial as well as ethical and social, for the architectural culture and the state of permanent curiosity that distinguishes his research, many terms (and commonplaces) have been employed to define Prouvé: architect, engineer, builder, entrepreneur, inventor. But not even Le Corbusier managed to define him unequivocally, by introducing the image of ‘homo triplex’ (architect-engineer-building, in Modulor II). In reality he seems closer to the master-builders of Medieval architecture, working moment by moment to keep together figures now centrifuged by the process of building production, to avoid that deplorable parceling out of tasks that inevitably extends the time required for realization, with consequent weakening of the initial content of the project, of the original idea. Within this context he developed a ‘processus du travail’ under the sign of the multidisciplinary and the interdisciplinary, and even exploiting the special fields of knowledge of technicians from sectors not strictly linked to architecture (such as aeronautical engineering). Prouvé was born in 1901 and spent much of his life in Nancy, where he died in 1984. He worked as apprentice with the ferronier d’art Zabo, from whom he learned the secrets of forging. At Nancy he began his professional career in 1923, opening his first studio (Ateliers Jean Prouvé). “I was born at the school of Nancy […]. They had a law that was instilled in me: man is on this earth to create […]” Prouvé frequently recalled. Undoubtedly, he was deeply impressed by the experience of the Nancy School (1889-1909), a local development of the Art Nouveau movement, whose spirit it always retained, the ‘Nancy spirit’, a sort of moral of invention, an intellectual disposition “to be modern, without compromise”. The Nancy School promoted continuous research, the expression of a cultured, enlightened craftsmanship that looked toward industry, imbued with ethic and social ideals, giving a voice to new materials and new techniques, the true foundation-stone of its particular aesthetics. Prouvé chose steel plate for his major production, but also used aluminum plate, wood, and perspex. He experimented with combinations of materials and with their workmanship, utilizing the ‘outils’ made available to him by technological development. Electric welding freed him from the forge, the use of pressing-bending machines of increasingly superior performance released his building concepts to soar in freedom. Steel sheet in rolls, produced by the metallurgical industry, four meters wide, of thickness ranging from 10 to 25/10°, was welded, bent, drawn, punched, seamed and bolted, to become pilasters, beams, sheds, walls, stairs, windows and lastly panels, with the dream of constructing mass-production buildings: ‘l’industrialisation du batiment’. In 1930 Prouvé was in Paris. He was in contact with Mallet Steven, established close friendships with Janneret and Le Corbusier, with whom he founded the UAM (Union of Modern Artists), whose members also included Beaudouin, Chareu, Ginsberg, Lods, and the Lurçat brothers. Prouvé wanted to apply the methods of industrial production to the building sector. He was fascinated by the perfection of the automobile (2CV is a paradigm of such perfection), of the airplane and the train, which he contrasted to the backward state of the building sector. “If airplanes were constructed the way houses are, they would never fly”. He conceived of building as a system made up of elements-components that interact with each other in a complex equilibrium of static forces and functional devices, in the same manner as a mechanism (one to be lived in, to paraphrase Le Corbusier), with no formalistic concessions. The technical figures designed by Prouvé speak of their own functioning, express their modes of construction, equally distant from any form-function determinism and from a mechanistic aesthetics as pure option of taste. “I have never designed forms, I have built constructions that had a form”. His research, although supported by the French technological avant-garde, divulCIAM and the OTUA, encountered numerous problems in the production sector.

The entrepreneurial lobby refused to believe in the possibility of a development of metal structural work applied to the building sector (preferring to produce casseroles rather than houses) and the great chance represented by the need for post-war reconstruction was missed, despite the initial orders (and promises) of the Ministry for Reconstruction, since reinforced concrete, a ‘patriotic material’ was preferred over metal materials. Between 1931 (date of the foundation of the anonymous company Les Ateliers Jean Prouvé) and 1954 (sale of the Maxeville workshop) an incessant series of projects and prototypes for individual and collective housing was forthcoming. The week-end and vacation house BLPS (1935), transportable and rapidly erected by simply jointing its components, ten square meters in size, “to free people from dependence on hotels”; the 3×3 meter house for the army (1939), which could be erected by three men using components transportable by one man alone, mass-produced in eight hundred units up to the outbreak of the war; the houses for the wounded of Lorraine and Vosgi (1944) of the ‘axial portico’ type, 8×8 meters and 8×12 meters, produced in eight hundred units to fulfill the order of the Minister of Reconstruction Dautry; the 8×8 meter houses ‘with portico’ for the reconstruction of the Sarre (1945); the tropical house for Niamey (1949), with aluminum components, transported by air in a Bristol cargo plane to Africa for the purpose of demonstration, the Meudon houses (1949), with axial portico and
with shell; the Citroen shell dwellings (1950); the Alba ‘central core’ house; and the houses for abbé Pierre (1955). It is significant how the building is expressively portrayed through the salient principle of its composition: its erection. The stages of erection of the Metropole type carried out at Meudon are described in detail in the Studal catalogue. The first stage includes the laying of the foundation-basement, consisting of a floor with steel structure resting on stone sectors. On the floor level is placed the structural element, the ‘portique’, fixed to it by a pin; on the structure and on the border beams rests the roof-beam. The next stage consists of mounting the roof, formed of self-bearing aluminum elements put in tension through the tie rods of the facade. In the final stage the curtain walls are positioned and fixed with anchoring section bars. The studies were rarely put into production, with the result that the Maxeville workshop, a risky investment made to meet the political promises of a market for light prefabricated emergency houses, was absorbed by the Societé de l’Aluminium Francaise (1954) and Prouvé was confined to the research department. This was a defeat and a trauma that definitively
shattered the dreams of the master from Lorraine. “They have cut off your hands”, Le Corbusier wrote him, “try to manage with what you have left”. Nonetheless, a series of prefabricated prototypes and buildings realized prior to World War II testify to the extraordinary quality of his research. The flight club Roland Garros (1935) but above all the Maison du Peuple (1936-38) were to realize the dream of the Modern architects to construct a building produced entirely industrially.

The Maison du Peuple, designed in collaboration with the architects Beaudouin and Lods with the consultation of the aeronautic engineer Bodiansky, is a technological meccano with variable positioning (entirely shop-built in pressed-bent steel and dry-mounted on site) which resolves the complex functional layout – a Maison du Peuple (with a hall for meetings, festivities and cinema and offices for trade union representatives) and a covered market – through a system of mobile walls and floors that can slide-translate-compose itself to transform the spatial and functional layout. The market is located on the ground floor. The two main stairways, which can be closed off through a system of rolling gates, make the entrance to the upper hall independent of the market area. On the first storey the floor has a central core made up of a system of eight elements, 17×5.50 meters, which slide through a system of winches and tracks ‘into’ the technical block (armoire a planchers), thus unifying the space of the market and creating an annular gallery. The skylight in the roof can be opened through an electric device, transforming the market ‘en plain air’, in the interests of hygiene, air and light, the basic principles of the New Architecture. In the ‘closed’ arrangement of floor and skylight, the first storey serves as hall for meetings and festivities with a capacity of 1500-2000 persons. By operating a system of sliding walls, this floor can be transformed into a cinema-theater, even an openair one, for 700-800 persons, equipped with foyer, bar and independent entrance. The static structure consists of a series of parallel portals in steel, longitudinally braced, with an interval of approximately 5 meters, which mark the rhythm of a ‘nave-like’ layout, the central nave measuring 17 meters and the two lateral ones 11.50 meters, for a longitudinal extension of 45 meters.

The ‘skin’ of the building a ‘mur-rideau’ formed of panels of two different types: a translucent panel delimits the volume of the main body (the ‘hall’), while an opaque panel distinguishes the services body (the scenic tower), emphasizing the functional and volumetric hierarchy of the parts. The translucent panel is of the composite type, formed of an outer layer of 8-millimeter flashed glass and an inner layer of ‘Rhodoid’ translucent material, separated by an air gap for the purpose of insulation. The panel is installed through a hanging steel structure, the so-called profil radisseaur, consisting of a series of box-type sections of open ogival shape serving as windbreak. The opaque panel on the scenic tower (dimensions 2953×1034 millimeters, interval 1040 millimeters, joint 12 millimeters) is instead a complex layered functional mechanism designed to resist wind load thanks to the particular form of its cross-section. The steel sheet that constitutes the outer shell and the finish is stiffened through a spring-operated mechanism that shapes it convexly, producing the characteristic vibration of the façade under the rays of the sun. The heroic period of Maxeville having concluded after 1954 Prouvé became an ingenier-conseil, acting as director of the research department of the CIMT (Compagnie Industrielle de Matérial de Transport) and as professor at the CNAM (Conservatorio Nazionale Arti e Mestieri), Chair of Applied Arts. For the CIMT he created light facade systems, as completion of school buildings, residences and offices, carrying to an extreme the theme of the mur-rideau. Concentrating on the panel, he worked on the ‘skin’ of the building utilizing steel sheet, aluminum sheet and glass, moving in the direction of greater complexity of the basic component, adopting the principle of integration or that of separation of the functional elements that make up the system: brise-soleil, parapets, windows, aerators, are raised to the role of architectural figures which determine, without camouflage, the overall image. Two salient examples. In the residential building located in Mozart Square in Paris (1953) each panel, of the sandwich type, is divided horizontally into three parts: starting from the bottom, a railing, a sash window and a ventilation band. The outside of the railing is free to slide vertically (like a blind) but also to rotate around a pin (through a telescopic arm mechanism), to control the flow of light into the rooms. The innumerable reciprocal arrangements of the curtain wall elements determine, in the daytime and at night, different positioning (and lighting effects) of the mechanical front of this building, in constant movement and transformation In the Unesco Building V in Paris (1968), the principle is that of stratification as regards the separation of the window frame from the brise-soleils, which become independent figures. Over the ‘porthole’ window-panel (proceeding from inside to outside) is superimposed a layer of anodized aluminum sheet bent at the ends to create half-crests which, through successive juxtaposition, determine a sequence of vertical brise-soleils. The third and last layer is formed of horizontal planes of grating (extruded aluminum), arranged shelf-like and providing still further protection against sunlight. Prouvé thus appears as a great inventor of prefabricated systems, prefiguring not only extraordinary, complex structural systems but also a building concept that is still today a milestone; a concept in which we find again, along with the cogent necessities of the profession (the rules of those who design for building), those ontological requisites now overshadowed by the market of the image.

Diego De Nardi

[MATERIA n°37/2002]

 

Essential bibliography
AA.VV. Jean Prouvé. Une architecture parl’industrie, Zurigo 1971.
Dominique Clayssen, Jean Prouvé, l’idee
constructive, Parigi 1981.
Catherine Coley, Jean Prouvé, Parigi1983.
J. F. Archieri – J. P. Levasseur, Prouvé,
Cours du CNAM 1957-70, Liegi 1990.
D. De Nardi, Jean Prouvé, Torino, 2000.
P. Sulzer, Jean Prouvé Oeuvre Complete,Voll. 1 e 2 Tubingen-Berlin, 1995-2001.
AA.VV. Jean Prouvé et Paris, Parigi 2001.