Prefabrication experiments - 392 - customize - 03 - Plug-in dwellings

 

When it comes to prefabrication and industrialized building systems, it seems everything old becomes new again. Ideas from the past get fresh imagery and are wrapped up in an era’s vocabulary to argue for innovation in architecture and construction. Adaptability is one of these reemerging concepts that entices architects to envision ways of making edifices flexible enough to respond to both minor organizational changes and major modifications required for retrofitting according to evolving requirements. The plug-in rhetoric of Metabolist architects in post war Japan posited capsule living as the future of adaptability. Inhabitable manufactured pods would simply be attached or plugged into a collective infrastructure. These functional commodities could either be moved, replaced, or altered over time. Architecture was viewed as peripatetic.

 

Kisho Kurokwa’s Nakagin Capsule Tower epitomized this concept for generations of architects. Ultimately, it proved marginal and ephemeral with the building coming down in April of 2022. Still, the plug-in concept captivates architectural education and design strategies. Peoples Architecture Office of China has renewed these strategies on recent projects including their plug-in school and plug-in tower. The Plug-in Tower closely mimics the systemic separation of support services from their appended mass-produced dwelling pods. The mega spaceframe structure, an oversized version of the famous Mero^TM space frame node, is intended as an adaptable framework espousing any site; the office’s proprietary plug-in panelized sub-assemblies compose prismatic inhabitable spaces within the steel web. The factory-made panel is described as including all mechanical necessities along with interior and exterior finished surfaces. Other functional systems and circulation elements are added-on to create a total comprehensive building.  

 

The prototype is represented as a single-family dwelling without permanent foundations as the steel trellis structure can be anchored to any site; the plug-in dwellers could disassemble the house and take it with them wherever they decide to live. Further, the space frame structure can grow vertically and horizontally adapting to suit changing requirements. A contemporary version of ideas explored during the latter half of the twentieth century, the romanticized mobility and architectural interchangeability reveal more about the theoretical artefacts produced by the profession than it does about tangible applicable adaptability for housing. 

Plug-in prototype from Peoples Architecture Office

Prefabrication experiments - 391 - customize - 02 - Assembly OSM

 

Founded in 2019 by brothers William and Chris Sharples of SHoP architects, Assembly OSM is a start-up intended to revolutionize the way buildings are put together. The architects’ digital design practise, established in 1996, inspired the firm’s founders through several large-scale urban prototypes to expand their digital principles to the entire construction process. Like the now defunct Katerra before it and a growing list of other ventures into digitally propelled industrialization that would bring manufacturing methodologies to streamlined construction, will Assembly OSM finally bridge the enduring gap between architecture and industrialization? The team is certainly accomplished and leveraging what they’ve learned on several modular projects, Barclay tower in New York is the most famous, may qualify them to achieve what so many others have only proposed. 

 

Automobile production has long been a reference to modernize building and improve stagnating construction productivity. Kieran and Timberlake’s manifesto (Refabricating Architecture) in 2004 shifted the narrative to include airplane production and shipbuilding with complexities which more adequately reflect the systemic organisation of buildings. Assembly OSM’s discourse parallels these ideas and platform theory proposed in 2017 by Bryden Wood. These theoretical outlooks point to a type of mega kit method for making multiple bespoke buildings from the same basic parts.  This is not necessarily a new idea; buildings are always made from the same components from doors to windows and a multitude of other industrialized components.  Endeavours like Assembly OSM strive to streamline design with production through the normalization of parts in matters of dimensions, characteristics, and performance, to address the entangled mess of a highly fragmented building construction sector. 

 

Creating a harmonized procurement, planning and coordination process replicated from project to project is the way forward for Assembly OSM inspired by an integrated design and production process that exists in industrial fabrication. In construction, the IPD integrated project delivery method invokes a similar framework for sharing responsibility among stakeholders and laying out every part of the process before it is undertaken. Groups like Assembly OSM, Bryden Wood, Factory OS are promoting this approach, and while digital innovations hold new potentials, the question of - will this be the one ? -  persists.

Left: 290 Mulberry Street (2008); Center: Barclay's B2 Tower (2016); Right: Assembly OSM value proposition

Prefabrication experiments - 390 - customize - 01 - Renzo Piano's «Platform» approach at Corciano

 

After more than a century of consideration and marginal application of manufacturing principles in architecture, the chief sticky point endures: combining efficient, normalized and reproducible processes to a plurality of arrangements without compromising architectural uniqueness. Offsite construction entails many forms of standardization: from harmonizing supply chains to regulating dimensions for components or systems to amortize and distribute costs over multiple objects. Although variations are possible, normalization is key to economic viability. Component based systems, generic kits-of-parts have been proposed to bridge the need for well-ordered parameters with customization. Bryden Wood's platform DfMA approach proposed the implementation of a steel skeletal framework with specialized connectors to create open frames «hosting or accommodating» variable functional requirements articulated to quantified typological criteria. This type of idea, while certainly flexible, still demarcates architectural compositions, replicating syntax from project to project, limiting architecture’s habitual ambitious singularity.

 

Renzo Piano's Rigo Quarter Corciano, an «evolutive» housing system constructed in Perugia, Italy in 1978, foreshadowed Byden Wood’s «platform» approach long before the term was employed in relation to construction. The design and completion process proposed a coordinated steel frame structure arranging linear dwelling cells divided by concrete partitions. Joists, girders, columns, precast concrete panels, and a plug-and-play curtain wall were the scheme’s main components.   Interiors were generic spaces planned according to inhabitants’ needs. Coloured curtain wall panels composed varied elevations to differentiate neighbouring units. These dimensionally normalized curtain wall façades enclosed the flats’ view-oriented elevation while retaining walls anchored the units’ slope-side ends. The kit ideology orchestrated the building and its sitework as an evolving assembly line. All phases were sequenced with an optimized just-in-time production strategy. Prefabricated service cores or pods provided dwelling services within the flats. 

 

This type of «kit» duality (a mass produced kit uniquely disposed over multiple designs) was specifically rationalized for affordable dwellings and could be adapted to any site. From Gropius' expandable house to Piano's robust process at Corciano and even Bryden Wood's optimistic understanding of innumerable variations from standardized parts, the industrialised repetition is still seen by some, certainly by many architects, as perpetuating the sameness that epitomized prefabrication failures.

Left: Platform approach (Bryden Wood); Right: Housing Project at Corciano Courtesy of Fondazione Renzo Piano

Prefabrication experiments - 389 - Global evolutions - 09 - Germany

 

In the years following the first world war right up until the 1960s, German housing policy deployed prefabrication of reinforced concrete elements to develop low-cost experimental communities (Seidlungs) to test prototypes of modern design and production. A notable example of the centralized strategy, Ernst May's precast slab housing brigade, conceived the «plattenbau»: a large panel standardized, highly replicable system for dwelling provision. 

 

The deep-seated manufacturing culture transformed design education as well. The Bauhaus, Germany’s comprehensive design school headed by Walter Gropius, inspired many young practitioners and artisans to look to industry to reform existing production patterns to shape a fresh aesthetic palette for architecture. The relationship between industrialization and architecture is arguably the most symbiotic when compared to other industrialized nations.  Major players like Christoph and Unmack or Hanse Haus, have been producing precise timber structures for more than a century.

Prefab market share is around 23% of new housing starts, a staggering 1 out of every four. The panelized timber kit is driving a turnkey model with a one stop shop convenience, which is also anchored to holistic sustainability markers. With high social acceptability, prefab in Germany symbolizes precise fabrication, high quality design, advanced production methods, valued materials, and efficient construction.  Brand equity positions prefab zeitgeist on par with industries like German automobile fabricators, Volkswagen or BMW.  Even with the mature market, the industry is fragmented. Five top producers account for 30% of production with the remaining 70% being shared among companies holding 3% of the market. 

HAAS Fertigbau’s kits exemplify the most generalized strategy providing services to design and manufacture timber panel kits according to consumer specifications. The company promotes efficacy, tightly finished shells and energy savings. Another well-known producer, Weberhaus promotes similar construction methods and parameters to achieve a high-performance wall envelope within a conventional stick frame structure. The stud cavity is insulated and a continuous layer of insulation over the skeleton eliminates any thermal bridging. Along with some of the most advanced factory mechanisation and robotization, assembling these kits is material, time and cost efficient. The panels can be flatpacked for optimized just-in-time transport and sequenced for streamlined onsite assembly.

Christoph & Unmack portable buildings (left); Advanced prefab manufacturing (right)

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)

Prefabrication experiments - 385 - Global evolutions - 05 - UK

 

Conservatory builder Joseph Paxton’s experimentation with prefab elements to assemble the Crystal Palace for London’s world exposition (1851), Henry Clayton’s brick making machine for Atlas Brickwork (1855), and exporting rolled corrugated iron kit houses to various British colonies, Great Britain, the birthplace of industrialization developed first manifestations of manufacturing harnessed for building construction.  With the success of mass production and commodification, it’s astonishing that conventional construction has not implemented higher levels of prefabrication. Housing shortages, post war rebuilding and redirecting war economies towards construction drove prefabrication between and after the two world wars. Innumerable prefabs were commanded in the years following World War II. Much has been written about these explorations and their non-traditional construction methods.  Like housing, school construction to serve burgeoning communities was also identified as an outlet for British prefab systems. Suspect detailing, lack of weatherproofing with porous envelopes deepened prefabrications’ enduring negative connotations. Only about 7% of new homes use comprehensive modular or industrialized building systems. Schools and houses are once again a priority for increasing construction’s productivity as the affordable housing crisis is a global challenge requiring heroic approaches.

 

The UK has remained a figurehead for prefab’s theorization even with marginal practical applications of modern construction methods. Bryden Wood’s Bridging the Gap between Manufacturing and Construction published in 2017 established the firm and the UK as contemporary trendsetters redirecting effective manufacturing concepts such as Design for Manufacturing and Assembly towards building processes.  The firm explored platform theory’s potential to cross-pollinate building types, their assembly details and mass manufacturing with supply chains by comprehensive centralized data management to streamline design, fabrication, assembly and building operation. This construction 4.0 take on renewing prefab is driving a veritable industrialized building renaissance.  A sign of current attention to the UK’s market, after 60 years in the Japanese sector, Sekisui prefab homebuilder has introduced Shawood, a skeletal timber version of their housing system designed specifically for the UK. Partnering with Urban Splash’s modular housing division, Sekisui’s enduring chassis model was directly in line with platform, modularity and customization concepts more than half a century before Bryden Wood’s manifesto.  

Crystal Palace (left) ; Bryden Wood's systematization (middle); Shawood detail (right)

Prefabrication experiments - 384 - Global evolutions - 04 - USA

 

Constructing a prosperous nation during the industrial revolution framed the United States’ normalized building culture centered around specialized trades, abundant resources and archetypal construction systems. Steel skeletal frames and light wood timber balloon frames were the building blocks of territorial and economic development; Steel for the vertical dense city and timber for horizontally sprawling suburbanization. Henry Ford's assembly line inspired an ideal relationship between mechanization and mass production through the systemic categorization of building products.  Bespoke buildings produced artisanally were replaced by the detailed assembly of manufactured pieces leveraging high levels of repetition in design, supply chains and management processes. 

 

The union of American pioneer spirit and the democratization of the assembly line as a way forward led to the development of the iconic mobile home. Its affordability and simple untethered purchasing process made this industrial artefact highly successful, and it has remained the most applied form of factory-made housing. The United States was also the stage for the twentieth century’s most ambitious building program; HUD’s Operation Breakthrough in 1969 subsidized experimentation and production capacity to test industrialized construction for multi-unit urban residential buildings. The program led to 11 test sites demonstrating the application of affordable mass housing prototypes that were never generalized.  

 

Even with all its rich history of offsite construction, market share of new housing starts is marginal but being driven by a resurgence of similar challenges that drove previous uptake initiatives: affordable housing shortages, limited specialized labor, rising costs, stagnating productivity in construction, and environmental constraints. Articulated to these contemporary needs, HUD is once again underwriting research to normalize and organize prefab potentials. The market is saturated by small companies and stacking volumetric units made by mobile home producers are explored as prospective collective housing methodologies. Larger Flagships like Z modular, Blokable, VBC and to a certain extent Katerra (now defunct) are using information technologies to transform design and building approaches. Integrating BIM and other supply chain management tools offer comprehensive solutions to assemble factory made boxes designed and produced specifically for high density residential, institutional, or commercial purposes.  The industry is set to grow quickly, and prefab's connotations are being reformed in favor of a modular building sector that is innovative, proactive, efficient, high quality and fully customizable.

From left to right : Rollohome mobile home, New Jersey test site (Descon / Concordia), Z modular's open volumetric building system

Prefabrication experiments - 383 - Global evolutions - 03 - Australia

 

Australia has a rich history of prefabrication. During the mid-nineteenth century gold rush, massive prospecting migrations framed a fertile environment for the delivery of moveable houses to set up temporary barracks and communities. Corrugated iron houses dispatched from Great Britain are the most notorious and the rolled iron sheet metal became a form of industrial vernacular in Australian modern architecture. Notwithstanding some of these emblematic traditions, prefab is still marginally applied in Australia with only about 3% of new construction deploying industrialized construction systems. With contemporary needs and challenges driven by ecological constraints along with increasing urban populations, Australia like other industrialized countries is directing policy and industry stimulating a renewed interest in offsite construction: achieving more, wasting less in a quality controlled environment. Further, inflation and a dearth of traditional trades have increased construction costs and made housing affordability a major obstacle. 

 

Pushed by lobby groups, the centralized hub of all things prefab in Australia, prefabAUS https://www.prefabaus.org.auis educating consumers, and government housing provision stakeholders towards greater knowledge sharing regarding potential systems and the advantages of prefabrication to reach a 10% market share; a 7% uptake that will require an concerted effort form all concerned parties. Modular volumetric, in particular, is being touted as a way forward for the Australian offsite construction sector. From completed flats, to utility rooms and bathroom pods, factory produced boxes intelligently assembled make quick work of any building type as they can be completed up to 70% offsite. Smart Base^TM and Fast Hook^TM strategies marketed by pod manufacturer Pacific Australia are showcasing how modern methods of construction can transform production from intensive site based management to efficient manufacturing methodologies. Austruss, Buildom, Dynamic Pods, Hutchinson Builders, Interpod, Platinum Pacific Australia, Podium Pods, Puda, Schiavello and Sync (Hickory Group) are companies supplying this type of functional unit in glass reinforced plastics, steel or reinforced concrete. Consolidating market forces is one of PrefabAUS’s greatest potential strengths and cross-pollinating industrial partners leads to a mature market place ensuring that a 7 % market growth doesn’t lead to another era of connoted prefabs but a robust alternative to onsite archaic practices.

From Iron Houses to Modern Methods of Construction