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

Prefabrication experiments - 382 - Global evolutions - 02 - Sweden

Countries with a fertile timber industry also have developed a productive component-based building culture. Sweden has an engrained and proficient prefab building culture going back to architect Frederik Blom's movable houses in the early 1840s.  Sawmill mechanization and regulation of the lumber industry were central in enriching manufactured housing’s path. Siwers and Winneberg, a Swedish timber kit manufacturer, delivered prefab houses to the USA during the 1849 gold-rush, even showcasing them at universal exhibitions. The driving forces of industrialized construction in Sweden were first, sawmill mechanization and second, dimensional and process standardization of components, products and systems for the construction sector. Building codes, detailed pattern books and modular coordination underwrote high levels of normalization. The industry continued to mature in the latter half of the twentieth century thanks to government initiatives boosting factory production to one million dwellings between 1965 and 1975, largely articulated to timber frame construction. A large portion of Sweden's housing, 84% of detached single family dwellings, use prefabrication or integrated sub-assemblies such as panelized walls or floors finalized to varied degrees delivered onsite for assembly. 

 

The industry’s development has made it a world leader in terms of prefab market share of new housing starts. Highly skilled workforce, quality timber harvesting and a robust industrial structure make for a perfect storm in terms of off-site construction’s future potential. The Swedish industry with examples like Lindbacks and Bloklok is seen as a model for other contexts looking to increase prefabrication's uptake. Lindbacks, particularly, is a highly successful and integrated company with a business model based on an intelligent combination of standardization and customization. Their posited 80-20 mix leverages a comprehensive design manual, with standardized organisations, explicit joinery, assembly specifications for engaging with external architects early in the planning process. The company also controls their own general contracting subsidiary that understands and complements the company's workflow from offsite to onsite and avoids costly errors due to general contractor ignorance. The Ikea model inspired Bloklok (also owned by Skanska) that has been producing modular homes since 1996; Bloklok modular homes propose to offer comprehensive quality from procurement to pleasant living articulated to the Ikea vision of standardized design with an affordable price.

Bloklok house factory and typical development

Prefabrication experiments - 381 - Global evolutions - 01 - Japan

Arguably, Japan has the deepest history of factory produced housing. Massive post war rebuilds combined with significant investment in industrial progress, notably in automation, and with modular building traditions anchored in local vernacular to spawn a prefabricated building industry worth 21 billion dollars in 2021. Known for flagship companies Misawa and Sekisui, Japan's prefabricated builders include other well-known players, Panasonic Homes, Toyota Housing Corporation and Tamahomes that share the market. Sekisui's (14000 units / year) model based on a skeletal dimensionally coordinated volume defines the basic concept of standardization leveraged toward varied aggregations. Other recent experiments including companies like MUJI partnering with well-known architects demonstrate the industry's willingness to propel new trends. With 15% of all new homes being prefabricated, Japan remains a strong force of house manufacturing.

 

While industrial development and reconstruction forged the industry, high-technology narratives in the 1960s drove a unique outlet for Japanese prefabrication. Metabolist architects imagined mass-produced housing pods or capsules plugged-into vertical collective infrastructure. This dynamic form of urbanism would comprehensively reform city building. The recent deconstruction of Kisho Kirukawa's Capsule Tower in the spring of 2022 formally put an end to this futuristic vision. 

 

Beyond metabolism in architecture, Japan influenced global manufacturing with the most successful and comprehensive theory of production which continues to inspire efficiencies in the construction industry: the Toyota Production System. The theory, developed by Eiji Toyoda and Taiichi Ohno, proposes to reduce waste at every step of a process and led to Toyota becoming the most proficient car producer in the World. As disruptive as Henry Ford’s model was, the Toyota collaborative model outlined principles that were applied in other sectors and are now sometimes referred to as lean manufacturing or construction. Manufacturing parts or subassemblies for buildings can follow similar principles of elevating teamwork and eliminating waste. 

 

Ageing population is a structural probable that will affect prefab construction as well as housing demand in Japan. Declining national needs have encouraged producers to look outward to conquer other Asian markets with increasing housing demand. Japan’s sector uses some of the most advanced manufacturing techniques and continues to be a model for other countries looking to increase prefab’s uptake.

Three key ideas of Japanese industrialization applied to building

Prefabrication experiments - 380 - State of the Art - 10 - Plant Prefab and the smart house

Our contemporary lifestyle is comprehensively connected. Smart phones oversee every part of our lives from efficiently organizing our workdays, downtime, to our interactions on social media. This connectivity outlines immeasurable data sets containing what we want to eat, what we search for, where we want to vacation or what products we crave. Amazon epitomizes how our shopping habits are dictated by our online profiles responding to behaviors and even ordering products for us as they are required. Alexa, Amazon’s intelligent home device has taken the smart phone from the palm of our hands effectively linking our private spaces: Playing music, turning on lights or controlling indoor temperature and climate. The smart home was the next frontier for Amazon. Looking at housing supply as the next sector for development, the company invested close to 7M$ in Plant Prefab, a design and fabrication company, in 2018. 

 

Combining virtual design and construction with manufacturing principles, Plant proposes customized building kits based on modular panels, volumes, and cores: The Plant Building System. The company isn’t providing techniques that have not been employed before but is adapting and packaging them in a sophisticated way. Leveraging interest in modular construction and a growing need for sustainable building practices, the company’s process distills any home design to a complete kit using their 3 sub-assembly levels: panels, modules, cores. The modular and prefab system is advertised to be 50% quicker than conventional construction as systems are built in a controlled setting and can be manufactured concurrently to site infrastructure and foundations. This task overlap is responsible for time and cost savings.    

 

Plant proposes architecturally designed homes to democratize current aesthetic values. Uniting manufacturing with architecture and Amazon’s global brand creates a potential framework for marketable prefab that addresses any latent prejudices. Further, installing intelligent doorbells or providing other gadgets, the home of the future will not only be produced as a commodity but will include real-time monitoring. The disruption in the way we live will come not from the materials and building systems (hardware) but from the software preinstalled in these homes, potentially censoring every aspect of a user’s life, for better or worse.

Excerpt from https://www.plantprefab.com/architects-and-designers

 

Prefabrication experiments - 379 - State of the Art - 09 - Platforms, Kits, Industrialized Building Systems

 

Since the publication of Bridging the Gap Between Construction and Manufacturing by UK firm Bryden Wood in 2017, there has been a theoretical shift in the offsite construction industry; Architectural design driven by virtual modelling and data management has initiated a new era for industrialized construction based on a theory of platforms. Platforms relate to both software and hardware. Software circumscribes a project's centralized data management strategy and real-time cloud-shared content among all shareholders. Hardware as described by the authors of the now famous report, points to a kit-of-parts methodology imagined to produce buildings that share architectural, material and functional characteristics. Like many ideas in prefabrication, while discussed as innovative, this kit-of-parts, open source, collaborative form of industrialized building is hardly new. Architects like Walter Segal, Ezra Ehrenkrantz and theorist N. John Habraken argued for similar approaches, systemically layering for Ehrenkrantz' School Construction Development System, the separation of supports and infill in Habraken's case, and shared building methods for Segal. All can be deemed early applications of platform theory in architecture.

 

Arguably one of the most ambitious uses of platform theory before it was titled as such was Renzo Piano's Rigo Quarter in Corciano Italy, designed and built from 1978 to 1982. Based on rigorous modular coordination and repeatable parts, Piano's work used a combination of systemic layering and separating structure and infill to produce a large-scale urban development scheme. Co-designed through workshops with future occupants, the organization is based on a 6m. grid for arranging plans, section and topological aggregations.  The kit included precast concrete components for party walls (supports) that divide the landscape into cellular 50 - 120 square meter flats. Internal elements, off the rack posts, service cores, joists and girders along with curtain wall elements made it possible to adjust designs based on basic elements. Piano's design at Corciano is a very impressive scheme of platform construction that freely adapts to a terraced landscape. Adapting to site has not always been a strength off offsite construction, Piano's work shows an imaginative way of achieving site specific standardization.

Above: Platform by Bryden Wood ;
Below: Rigo Quarter by Renzo Piano

Prefabrication experiments - 378 - State of the Art - 08 - Covid field clinics

 

Crises can propel innovation in construction. Wars, pandemics, natural disasters, and political refugee migrations, have all commanded systems to expedite sheltering or rebuilding processes. The recent Covid-19 pandemic defined a need to erect adaptable clinics, hospitals and even morgues to either expand hospitalization capacity or in more acute cases to isolate and quarantine patients. Beyond the treatment of infected patients, separate testing and vaccination centers increased the strain on healthcare infrastructure. Arenas, congress centers or large gathering spaces were requisitioned to be momentarily transformed. Modular construction of popup hospitals was effectively displayed in the pandemic’s early phase; the two-story 1,000-bed Huoshenshan hospital was completed in 10 days. The overlapping of module production while preparing a site for construction, the main advantage of offsite construction, can lead to substantial time savings as demonstrated by the field facility in China.

 

Another example, STAATMOD (Strategic, Temporary, Acuity-Adaptable Treatment), developed by multidisciplinary American design firm HGA and produced by the Boldt company, is a pop-up multi-use modular volumetric field hospital. Each container-like volume integrates state-of-the art medical equipment and mechanical amenities to achieve the same level of care associated with conventionally built facilities. Designed for flexibility and adaptability, the boxes can be used as stand-alone clinics or clustered into dynamic organizations growing or shrinking the hospital as required by changing needs and conditions. Each basic building block unit is a modular 12.5 foot-wide x 40-foot-long x 10-foot high standard ISO sized volume. Many aggregations and assemblies are possible. The H-plan, repeatable, pattern illustrated by the architects proposes to build field facilities in isolatable wings to reduce contagion. Units can be delivered and set on exterior lots on permanent or temporary foundations or fitted into converted convention halls. The self-contained STAATMOD modules are a completely manufactured and hermetically sealed box. Their factory production is more conducive to quality control. Attaining a sterilized medical environment that is delivered quickly, inspected in a controlled workshop, and commissioned on delivery are other advantages of offsite construction as modules can be finished, and individually wrapped before being plugged in to keep them completely sanitized. 

Modular Field Hospital - design by HGA

Prefabrication experiments - 377 - State of the Art - 07 - Delicate Adaptive Reuse

Neglected stone dwellings, barns, and other derelict buildings have always been objects of romanticized architectural adaptations; the dream of transforming a ruin into a house for next to nothing and reviving it for a new era or use is of particular interest in an age of resource conservation.  In degrading old towns and regions, structures can be purchased for cheap by assuming the responsibility of rehabilitating the buildings, to breathe new life into demographically challenged communities. Renewing an old house requires the delicate touch of knowing what to get rid of and what to preserve that harnesses the spirit of place embedded in weathered stones. Prefabrication and industrialized building have little to do with vernacular building techniques, however, the creative interaction between old and new sometimes elevates both, providing an image of how classic building systems and modern methods of construction can complement one another in unique adaptive reuse strategies.

 

Nauman Architektur practise epitomized this idea by transforming an 18th century pigsty into a refined 21^stcentury showroom. Extensively damaged in the second world war, the building’s existing aged materials and shapes are framed beautifully by a precise timber panel system composed as a prefabricated prosthesis inserted into the existing stone structure. The planar timber structure is arranged as a type of autonomous volume, pre-assembled, lifted and slid into place. The internal form duplicates the arbitrary patterns of existing openings and serves as a background for stone bearing walls that clearly express their tectonic link to place. The plywood insert is capped off with a slick pitched roof detail amplifying the material dualities of old and new, thick and thin, light and heavy, craft and industrial production, stacked and surfaced, evident from every point of view. The prefabricated sleeve envelopes a flexible space that could be used as a multi-use living space. Turning a low road accessory farm building into an inhabitable modern space showcases the adaptability of architecture not only from a theoretical perspective but as a hands-on way of conserving and reviving history. Prefabrication in this case speaks to its potential for sensitive intervention reducing site disturbance to a minimum. 

Exploded axonometric and volume being inserted, project by Naumann Architektur

Prefabrication experiments - 376 - State of the Art - 06 - Add-on Componentization

 

Componentization is a direct consequence of industrialization. Parts, pieces, anchors, or assemblies are mass produced and include innumerable catalogued variations to create bespoke buildings. Modern buildings are all, in a way, kits composed of these manufactured parts. Design for Assembly was one of modernism's canons that conceptually defined component prefabrication’s applications. Assembling edifices from coordinated parts inspired dimensional coordination but parts remained disparate: interfaces and systemic coordination were rarely considered in parts production. Instead, romanticized harmonious detailing of diversely manufactured parts in building construction guided the architect's role in providing instructions for coherent integration. Applying Lean production principles, BIM modeling and even DfMA principles to component manufacturing is currently reforming the sometimes disjointed and entangled relationship between design, fabrication and construction.  

 

Componentization can be further enhanced by modularization, creating coherent dimensional, joining and production parameters, to produce elements designed to fit into or added-on to buildings. Premade bathroom pods, elevator frames, staircases, precast wall panels and manufactured balconies are all large sub-assemblies becoming common as offsite production is understood as an efficient and productive alternative to archaic and wasteful onsite construction.  Sapphire, a company based in the suburbs of London, produces balconies as a type of coordinated chunk devised to simply slide onto a building's structural system. The prefabricated balcony is an assembly of two main parts; the prism (deck and rails) is conceived with two framed openings that glide the floor onto extending brackets cantilevered from the building structure like the two extending forks of a forklift. These outstretched members can be bolted to steel beams or cast in concrete slabs. The two contact points reduce thermal bridging associated with continuous balcony slabs. The module is flatpacked, delivered on site and craned to be set at a specified height.  The floor «cassette» is lightweight and includes material choices for glass guardrails and decking. The company takes modern technology even further with their configurator «coach», an on-line tool deployed to customize designs from predetermined rules and dimensions. Details can then be downloaded and specified. This type of online catalogued part and process streamlines the relationship between design and fabrication through a type of preprogrammed personalization.

Sapphire balcony being lifted into place

Prefabrication experiments – 375 – State of the Art – 05 – MTP_Multi-trade Prefabrication

 

As buildings became more complex throughout the twentieth century, integrating an assortment of services, systemic entanglement came to characterize the construction industry's fragmentation. Piping, wiring, air distribution and conditioning designated a patchwork of trades competing for space, paths, and channels for distribution. Trade coordination, or lack of thereof, is at the heart of scheduling and cost overruns in building construction. Prefabrication and industrialized construction promised to reform construction by defining and manufacturing building systems streamlined for onsite assembly. Most systems have limited their scope to structure, as is the case with partial panelized and modular volumetric construction, mechanical coordination remains a challenge in harmonizing multiple stakeholders to produce a coherent network of services. 

 

Combining the advantages of prefabrication, primarily a controlled work environment, concurrent onsite and offsite progress, with the one-off architectural designs, Multi-Trade prefabrication mandates trades to collaborate, in a factory, to assemble chunks or parts of a building that will subsequently be delivered and completed on site. The multi-trade component is an co-creative/constructive process outlined by contractual documents that identify methods, materials, place of production, tools and responsibilities for each trade brought together to construct optimized sub-assemblies. This process rationalization increases efficiencies, reduces waste, and most notably has the potential to eliminate costly coordination errors. The idea has been deployed on complex projects by industry leaders like Skanska and has even inspired a segment of production: Multi-Trade Rack Prefabrication is specifically linked to mechanical distribution chunks that are fabricated offsite in modular formats to facilitate both design and construction. 

 

BIM (building information modeling) is the main driver and facilitator for this type of prefabrication. Digital twins provide fundamental documentation and information sharing tools to organize spatial and functional criteria, specify, design, and identify coherent routes for trade interaction. Virtually designing and assembling mechanical systems before they are built makes it possible to apply both rigorous organizing principles and a high level of standardization by modularizing mechanical racks. The success of MTP hinges on an integrated process and contractual clarity imposing a comprehensive overhaul of traditional procurement methods.

Base4 Modular prefabricated MEP racks