Prefabrication experiments - 388 - Global evolutions - 08 - France

 

France was the birthplace of reinforced concrete’s generalized application in construction. The basic elements of flat slab construction were developed by inventor François Hennebique at the end of the 19^th century and then brought to market throughout Europe and North America. The material's flexibility made it conducive to casting on and then offsite framed by mass production ideas. France’s experimentation with prefab has a long and rich history; The years after the second world war were a particularly fertile time for industrialized concrete construction. Responding to housing shortages or massive rebuilds, standardization made it possible to develop large amounts of low-cost housing using factory cast pieces. 

 

Raymond Camus’ panelized building became synonymous with prefabrication, housing millions of people within what became a connoted building type. The simplified version of wall and floor construction was deployed for dwellings all over western Europe inspiring similar strategies in Eastern Europe and eventually in North America.  Many of the most famous heavy panel systems were developed for the French market and unfortunately some of their negative connotations still affect prefab's penetration in France. Visceral reactions to high levels of standardization with suspect construction and weatherproofing methods connoted prefabrication as a low-cost, low-quality, impersonal form of building inevitably leading to social problems. 

 

The building process itself was not the problem. Isolationist planning strategies and urban renovation policies envisioned these buildings in bucolic landscapes with few local services creating dysfunctional communities that regrettably are associated with and symbolized by the building form. Recently, similar drivers that argued for industrialization in the mid twentieth century exacerbated by current labor shortages, the Covid 19 pandemic, process digitalization, stagnating productivity have inspired a renewed vision of industrialization notwithstanding low cultural adherence.  BIM (building information modeling) is reforming the building planning and construction toward integrated processes bridging manufacturing with design and management. Within the spectrum of possibilities and tuned to ecological imperatives, contemporary industrialized large panel systems using timber (CLT, light wood framing, modular) are being promoted by the government as a carbon neutral building strategy to affordably supply various building types and improve construction’s efficiency.  

From Raymond Camus to CLT - panelized construction systems

Prefabrication experiments - 387 - Gobale evolutions - 07 - China

The Covid-19 pandemic exacerbated supply chain issues in the global economy, aggravated isolation challenges for existing health care facilities and combined with the characteristic struggles of the construction industry brewed a perfect storm for increased uptake and worldwide attention toward prefabricated building production. This backdrop along with exponential global population urbanization ballooning from 36% to 62% in 20 years defines an acute need for scaling production of affordable urban housing. In China, the government decreed a 15-year plan to expand industrialized building systems’ use to 30% of all new housing starts doubling the stagnating 10-15%. 

 

Construction in China is a highly fragmented sector; however exports of prefabricated buildings and sub-assemblies have matured to a 1.66 billion dollar industry making China one of the most important prefab exporters. The industry promotes volumetric construction over other systems and mega-hospitals built in a matter of weeks in reaction to the covid crisis demonstrated the extreme speed that can be achieved through the assembly of edifices with manufactured chunks. Contrary to traditional construction, building these health care facilities began while boxes were produced in a factory and then while volumes were assembled on site, manufacturing continued in a just-in-time coordinated effort overlapping site work with manufacturing schedules. Images of these rapidly built hospitals were seen the world over, and prefabrication was promoted as a strategic method to revisit construction’s lacking productivity and to supply all types of buildings affordably. 

 

Even before the pandemic, since 2017, China invested massively in domestic production specifically to define novel construction processes. While building hospitals did rely on prefabrication and efficient manufacturing, it is noteworthy that the entire planning and construction operation was directed by centralized governance afforded all powers and resources to reach a determined goal. Fabricating modules was the easy part of the process; designing a working efficient hospital in record time including all systemic and functional requirements is where the Chinese model supersedes conventional construction. Concentrating all decisions along with investing the required time and labor accordingly shows how a streamlined process could lead to redefining construction from a fragmented wasteful act to a coordinated and harmonized productive process. 

Modular hospital during construction

Prefabrication experiments - 386 - Global evolutions - 06 - Canada

 

Canada is well-known for exporting raw materials. Recently, however, both policy makers and industrial associations have taken note of modular producers from all over the world delivering building systems from as far as Eastern Europe and China sometimes using Canadian lumber. Trade conflicts over timber prices with the USA and increasing tariffs are also politicizing an interest in producing value-added locally sourced construction systems for domestic use and for export.

 

Much like the prefabricated building industry in the rest of North America, the sector in Canada is dominated by panelized wall or modular volumetric manufacturers spawned by the rationalization of stick frame building and the evolution of the mobile home industry. Whether erected on a modular relocatable chassis or delivered to be set up on a site-built foundation, the lightweight timber frames are produced deploying the same systems as their onsite counterparts, except for being fabricated in a climate-controlled environment. A substantial advantage in a country where winter conditions impose increased construction logistics accompanied by greater costs. 

 

Demand for housing is shifting from traditional single-family dwellings to multi-unit residential building and has inspired many manufacturers to redirect their processes toward the open juxtaposition or stacking of premade systems. Modular construction is also being driven by rising construction costs, labor shortages along with increased design and construction digitalization. 

 

Presently, the industry delivers approximately 12% of new single-family housing starts. The objective is to increase market share by at least two-fold of all housing starts in the coming years. Articulated to greater sharing of standards to ensure adequate sound and fireproofing required in the multi-unit space, application initiatives are taking root in different provinces. Specifically, growth in the mass timber sector, glue-lam or cross laminated products are identified as sustainable building materials with high levels of potential prefabrication. British Columbia’s housing authority is proposing a timber based modular Designed for disassembly kit-of-parts. The approach (lighthouse.org) combines the advantages of volumetric construction with the intelligent separation and layering of building systems to achieve systemic adaptability to reform construction’s linear processes and to mitigate waste associated with a building's renovation over its lifespan. 

Modular construction designed for disassembly (lighthouse.org)