Prefabrication experiments - 138 - settings - 9 - Lean manufacturing - the Toyota model

Over a century after the dawn of industrialized building, modular and offsite construction appear to be going through a third renaissance. Applying factory production principles to home building is hardly a new experiment as Henry Ford's theories initiated a compelling connection between architecture and the factory. Using the assembly line to produce enormous quantities of goods while increasing quality and reducing consumer costs required a revolution in every level of manufacturing from design, engineering, procurement, assembly and supply management. The Ford model was based on continuous production and a capacity to move inventory. Applying automobile production schemes to manufactured housing lasted through much of the twentieth century as the prevailing pattern particularly in the production of mobile homes. 

The 1970s and 1980s brought a revolution to factory production enabled by another giant of the automobile industry, Toyota. Endeavouring to improve efficiency, the Toyota Company focused on task performance as a gauge for overall output quality. Known as «lean manufacturing» the strategy is established on all components being delivered and assembled as they are needed. This more immediate method reduces waste and the amount of stocked inventory.  Lean production is defined by five ideologies: just-in-time production, automation (jidoka), low inventory (Heijunka), standardized components and employee collaboration (Kaizen). 

Applying the lean model to housing, the Toyota Housing Corporation builds light steel volumes, which are 85% completed in the factory. 28 different volume types are available. An average size house requires approximately 11 modules. The cellular construction system is based on stacking and stitching the large components together on site. Akin to large building blocks that are snapped together, the entire process form order to assembly can be as short as 45 days. Although not the largest producer, the Toyota home brand is coming into its own as one of the important home producers in Japan.

Toyota's business model functions on the same basic principle of the pattern book shared by many manufactured home companies. If the production model is highly efficient, the designs remain fairly conventional. Recently partnering with architects the company has established a line of contemporary models perhaps looking to achieve the same brand recognition as MUJI has established with partner architect with Kengo Kuma.

Stacking and stitching Toyota House modules

 

Prefabrication experiments - 137 - settings - 8 - Leisure prefab - «Habitat Léger de Loisir»

Travelling through the North American countryside beside a lake, behind a cultivator's home or in a densely wooded forest one is likely to come across simple structures such as the Quonset hut or the simple rigid A-frame. First initiated or promoted through military use for immediate shelter or utilitarian structures, this type of standardized kit building while accessible, never quite integrated the market as primary homes. However both eventually came to connote a type of ready-made functional, no-frills kit for secondary use, cottages or make shift cabins. 

The idea of an instant home, allowing owners to get away form the hustle and bustle of city life resulting from a consumer based post-industrial service economy, helped encourage the desire for this type of leisure architecture. Patrons were less inclined to want the singularity they dreamed of with their primary residences and were likely to adopt unconventional strategies. From the 1940s, geodesic domes, plastic shell houses and a plethora of other prefab cottage interpretations were developed in every industrialized country; a reflection of architects and producers striving to influence the future of housing through society's new fascination with leisure.

Eero Saarinen's unfolding house (1942), Jean Prouvé’s design for his double shell house (1952) and a particularly atypical design for the simple «Habitat Leger de Loisir» (1980) all shared the ideal of rapid construction and mobility through a stressed skin over an arched metal rib joist framework. Inspired by aircraft construction, The HLL (light leisure habitat) was available in three sizes - 26, 36 and 50 square meters at a cost of 17 000 – 45 000 French Francs (approximately 50 000 – 100 000 2017euros).

The Société Rochel construction company designed and manufactured the HLL or the Chalet Nova as a weekend house or for countryside holidays. The vaulted cottage was produced in the late 1970s. It could be delivered completed anywhere in France. An L shaped service space including kitchen, bath and sleeping areas circumscribed the free spanning open living area. Its composition followed a simple linear plan associated with any extruded single span structure: lateral walls and roof delineated interior space while both front and back walls, load-bearing, could be customized any other material. 

Above left : Prouvé - Below left : Saarinen - Right : Habitat Léger de Loisir

Prefabrication experiments - 136 - settings - 7 - industrialization : The House of 194x

The industrialized production of houses and buildings was the focus of many architecture and trade magazines in the course of the first half of the twentieth century as manufacturers, designers and inventors engaged in applying Fordist and Taylorist production models to building and construction. Predominantly to supply the wartime economy, industrialized building and mass-production could respond to expanding demand. Building methods had been influenced by industrialization since the nineteenth century as catalogued components and pieces began to percolate designs transforming traditional craftsmen into the sub-assemblers we know today.

A special issue of Architectural Forum in September 1942 entitled The House of 194X detailed a particularly fertile time for American prefabrication. The issue endorsed prefabrication as the most significant development in building techniques. All areas of the construction process were affected and the factory would yield the post-war house. The editors cited the 73 362 prefabricated wartime units produced by their contemporary industry as proof of the sector's proficiency. Applied to every dwelling function, it was the need for adaptability and personalization which characterized Architectural Forum’s avant-garde take on a need for a type of «open» prefab capable of achieving multiple design options based on component standardization and modularity. Sameness was not an option. If prefab was to succeed it «must be able to adapt to different needs resulting from changes in family composition as a family grows «older»». This simple yet lucid posture could easily be applied to today’s industry, which still overwhelmingly follows a pre-war mass-production paradigm.

Architectural Forum would continue to showcase industrialized building systems in the years that followed promoting prefab as cost effective, laboursaving and fast. Steel component based systems demonstrated the magazine’s open systems approach as components could be assembled to organize any design. The light steel Bethlehem system (AF: march 1943) composed of trussed joists and wall studs typified variable prefab as both wall and floor components could be mass-produced but deployed in multiple variations. As today’s prefab industry is again promoted as an efficient building strategy, a century of experiments still raise the enduring question of how to apply the necessary repetition required by the factory to the singularity demanded by the house.

Bethlehem Light Load Steel Frame (from Architectural Forum, March 1943)