Prefabrication experiments - 462 - Panelization principles

 

Panelization, assembling buildings with wall or floor factory produced panels, has succeeded more than other industrialized building strategies in becoming commonplace and widely used in construction projects. Framing on site is time consuming and generates large amounts of waste. Fabricating wall, floor or roof surface sub-assemblies in factories is an efficient way of erecting a building's structure without the more complex wrapping, transport, lifting and setting required in modular construction. Further, lightweight panel systems come with design freedom as their dimensions and parameters are less constrained by delivery prerequisites.  The advantages of panelization also include their low impact on conventional construction culture; Specifically for open panels used for framing, their implications for systemic coordination are minimal.

 

Timber panels are straightforward construction elements organized as stressed skins, composites, or even as hollow box-beam formats. While they range in configuration, the building method remains a standard lightweight timber platform construction. Beyond their onsite flexibility, their manufacturability and relatively simple tooling has made panels effective: A framing table with an insulation or sheathing table in a shed, organized in a linear sequence where elements can be cut, framed and then finished at arms' length is a prevailing factory arrangement. As compared to modular volumetric which offers its own advantages in terms of offsite systemic integration, panel-making reduces the number of trades, systems, components and logistics required in a factory. 

 

The single line setup with framing and sheathing tables is an affordable path for panel production:  The drawing accompanying this post shows a cut-off saw that prepares timber stock according to design documents. The cut timber elements are then carried to framing tables with conveyors reducing human effort required to carry materials. Using non-automated tools reduces important upfront costs but limits factory output. Weinmann is a well-known manufacturer of panel-fabricating equipment that has developed completely automated lines for increasing output. With this type of relatively affordable democratization of computer-controlled tools, tables equipped with panel bridges to place, cut, nail, lift and perform any number of programmed tasks are becoming common.  

Weinmann framing table and bridge + Simple linear panelization process

Prefabrication experiments - 461 - Miracle Truss

Designing coverings, bridges or other large spanning structures is central to both structural engineering and architectural conceptions. Industrialization and its application in building construction drove the development of many material and compositional innovations. Trusses in steel, concrete and even in timber highlighted the relation between spans and material distribution defining efficient geometries by precisely placing material to resist loads within its effective strain limits. Beam effect underscores these assemblies by modern engineers who fashioned trusses in every scope and scale to respond to the new architectural demands of the machine age; train stations, airports, ports, bridges, all implied optimally spanning space utilizing minimal material with maximum structural performance.

 

Combining the efficiency of trusses with the form resistance of compressive structures, like vaults, A-frames or Butler frames, the Miracle Truss Buildings company supplies a kit-of-parts truss for cruck-framing small buildings. The basic unit, a modern archetype, a Butler type portico frame is assembled from four onsite bolted components delivered separately to maximize transport capacities. The frames are adaptable to industrial as well as residential requirements. Leveraging the success of large metal buildings, pre-engineered-to-order according to site and contextual criteria, the Miracle Truss building can be designed using an on-line configurator aligned with its fabrication and supply chain logistics.

 

Bolted to standard strip foundations, the linear arrangement’s length is boundless with both gable ends free of any structural constraints. Each composing part, vertical elements and oblique rafters, is profiled according to lines of stress. A rigid frame in cross section, simple tension braces stabilize the frames laterally. Steel angles fixed to the trusses make it a simple task to add timber purlins to construct discrete envelope systems. This complete separation of structure and skin also leads to the structure’s potential disassembly and reassembly multiplying potential service lives optimizing resource use and reducing total carbon footprint of the steel's initial production. A multifunctional framing platform, the Miracle Truss reinterprets the modern ideal of truss effect and providing off the shelf building kits readily available for any context.

Miracle Truss building during construction

 

 

Prefabrication experiments - 460 - Notes in passing - 05 - Platforms for Life Timber Kit-of-Parts

 

The affordable housing crisis affecting many is pressing stakeholders to assess the lagging productivity of conventional construction. For building new dwellings or for retrofitting aging 20th century building stocks, traditional trades and procedures lack the required swiftness, optimized resource management and takt times that the present state of housing development economics requires.  Planning, permitting, financing, approvals and contracting are all time-consuming stages that can be facilitated by kit or platform approaches. Using predetermined processes, components and parts outlined to streamline procurement increases production capacity aligned with offsite construction potentials.

 

The Platforms for Life design system initiated by the Intelligent City project https://intelligent-city.com/urban-housing-product/ proposes a comprehensive building system that uses mass timber components in rationalized, standardized, modular and flexible configurations adapted and modelled for any site. Articulated to optimized spans in relation to flat dimensions, the online metrics configurator expedites preliminary feasibility studies that encompass all project criteria; ready-to-go from the initial planning meetings. The manufacturable parts facilitate everything from gaining city approvals to architectural detailing as projects repeat identical chunks, stitching and joinery. Each site-specific project is distilled as a digital twin integrating the design, fabrication, assembly and construction processes through BIM software.

 

Iterative studies are adjusted and tweaked in real time without losing their integrated manufacturability as grid-based aggregations all deploy the system's underlying DNA. Once confirmed, the parametric models include capacities for detailed design or even analysis. A prime example of digital based integration of the design and construction processes, each building is devised with the same parts, then sequenced and delivered to the construction site to facilitate assembly. The nimble industrialized building system includes criteria for reducing energy consumption, span optimization and topological diversity. This type of union between design, fabrication, assembly and adaptable just-in-time delivery exemplifies how DFMA and offsite construction are leveraged to respond to high demand by organizing a supply chain of stakeholders, professionals and products through centralized design devices harmonizing normalized hardware and software components.

Platforms for Life artist rendering

Prefabrication experiments - 459 - Notes in passing - 04 - LEGO® blocks as an example of platform theory

 

Platform theory and its relevance for building construction has been suggested as potentially harmonizing design variables with fabrication, construction and furthermore to facilitate a circular approach in construction as pieces used for multiple buildings would be designed as modular and interoperable. Hardware commonalities exist in construction as steel buildings, prefab concrete components, and a myriad of other assemblies are normalized to be used across diverse organizations using repeating parameters within singular designs. Using platforms for building construction is often compared to the automobile industry: cooperating manufacturers share dimensional and material components of their products’ underbellies. An equally interesting analogy to platform theory directed to making is LEGO® plastic toy brick variability; standardized toy blocks are dimensionally compatible, can be clicked and composed into an infinite number of designs.

 

Since the late 1970s and the LEGO®  patent’s expiry, the same type of toy brick expanded commercially where other companies, Mould King, Sembo, Cobi produce compatible products. The toy bricks have expanded to include software platforms developed to create and virtually construct a LEGO®  model, visualize its completion, categorize its required components and potentially even create a purchase order or a bill of materials that is coordinated with producers – an idealize vision of applying DfMA in architecture. 

 

LEGO® Digital Designer, Mecabricks, and BrickLink studio are three configurators that offer users similar capacities to test their designs and share them with an online community of plastic brick architecture designers. Linked to online sharing sites, these configurators, a type of LEGO®  Information Modeling, communicate modular coordination principles, automate take-offs, facilitate cloud sharing and distribution. On-line communities also use these platforms to buy and sell, new, repurposed, or vintage pieces that multiply design potentials. 

 

This approach to crowd sharing and interoperability could be directed toward building design and fabrication. A configurator for personalized designs from a catalogue of interchangeable pieces based on bulk purchasing, automated estimating, working drawing packages and shop drawings frame a formidable strategy from which users create buildings of any scope and scale from a regulated and categorized number of predetermined subassemblies.

LEGO® blocks

Prefabrication experiments - 458 - Notes in passing - 03 - Transatlantic sharing - Alvar Aalto's timber houses

 

 

Spreading knowledge globally about new systems was instrumental in bringing industrialization principles to the normalized construction of massive amounts of housing during the postwar era. The impetus for standardisation to increase housing supply was directed by the diversification of production. Everything from framing materials, to doors and windows, all of which had been produced in artisans' workshops were now being made in a factory setting. This novel approach to making was suggested by production methods promoted by parallel industries sustained by new tools and materials. Mechanization influenced global construction methods and, in some way, even inspired architects to become protagonists in their own countries to showcase industrialization’s potentials.

 

An interesting case study in this globalized cross-pollination is the impact Alvar Aalto had in bringing American framing models to Finland. Collaborating with forestry vertically integrated giant Ahlström, Aalto was familiar with the company’s understanding of oversees innovations concerning sawmills and dimensional mass production. To push this collaboration further and because of his growing reputation, Aalto was invited to teach at MIT in 1940 where he also learned from the Bemis Foundation, a pillar of research toward building standardisation in the USA. Albert Farwell Bemis, the research foundation’s founder partnered with the MIT to explore modernising construction methods, specifically through dimensional coordination. 

 

Aalto’s time in USA was short but intense while MIT and outlined timber framing standardization principles for affordable housing. When he returned to Finland, he continued his partnership with Ahlström developing a series of AA houses based on the principles he had learned in his transatlantic mission. Finland was undergoing a housing crisis as many new towns had to be built to accommodate displaced populations from ceded territories. The transformation of Finnish building culture from onsite intensive craftsmanship to high levels of prefabrication differed from the American model in as much as it contributed to inventing a new player in the Finnish context: the integrated home builder.  The American model remained highly fragmented divided up amongst multiple stakeholders. The AA system deployed technological dimensional coordination principles, identified as flexible standardisation as the homes could be serialized as well as lightly customized though repeating underlying framing systems, details and components.

Alvar Aalto's AA type houses

Prefabrication experiments - 457 - Notes in passing - 02 - Customization and industrialized building

Demand in line with scaled production with little or no changes in manufacturing processes is industrialization’s recipe for offering quality products at low prices. Mass customization yields these advantages without compromising replicability through manufacturing a product offering that can be diversified by purchase options. In cars, shoes, boats, or smartphones this diversity is often limited to colors, aesthetic add-ons, and performance options. Selected modifiers adjust production processes marginally. Spreading branding, design, planning and investments over a stable client pipeline demand is the basic principle of effective manufacturing. As it relates to industrialized building, variety challenges and difficulties lie in how to frame choices or options. Consumers have grown accustomed to the high level of fragmented trade-based personalization in the built environment.

 

In the prefab sector many companies relay individualization as a strength; Customizing options include everything from exterior materials to faucets and flooring materials. While this certainly leads to a distinction in the final product and an ability to sell prefab as, just as customizable as conventional construction. Many options are counterproductive to a successful business model. Harmonizing supply chains for bulk purchasing implies a sameness through projects to reduce costs. As the prefab industry has often been compared to the automobile sector, it would seem ridiculous for clients to demand a particular steering wheel or an analog dashboard in lieu of a digital one. Options are limited to what is manufacturable within the same optimized processes tweaking them minimally for product differentiation.

 

The same type of standardization would be required to elevate offsite construction to the status of industrialized construction at least for it to be profitable and affordable. Making multiple products the same doesn't only revolve around dimensional sameness as has been the case for prefab for decades; Repeating products, patterns, finishes, materials, and methods is instilled in a building manufacturer’s genes. Does the drive to please consumers oppose the need for replicating models ? Companies like Boklok, founded by Skanska and Ikea, have directed personalization to interior lifestyle choices within an identical shell gearing repetition as a selling point. 

Housing development by Boklok (Skanska and Ikea)

 

Prefabrication experiments - 465 - Notes in passing - 01 - Brand Equity

 

Several rebranding efforts throughout the 20th century from prefabrication to manufactured housing to factory-built and to offsite have struggled to shed biases against prefab. Digital technologies frame DFMA and platform theory as the latest labelling and a reenergized position for industrialized building systems. Virtual design tools, coupled with housing crises, labour shortages, climate change and a better grasp of modern methods of construction potentials to address the cited challenges add up to a fertile era for factory-built architecture.

 

Prefabrication still deals with postwar connotations which have impeded a more generalized use. Even with companies using robust marketing, buy-in from architects and consumers remains tenuous. Katerra's meteoric rise and subsequent equally quick demise is a case in point. Even with massive investments supporting it, the once flagship of innovation failed. Was it bad planning, bad branding, or too big too fast ? Certainly, a combination of many factors led to its shutdown. 

 

While branding yourself as an innovator elevates your position as a potential disruptor in a slow-to-move construction industry, it also supports the idea of being off the mark, unconventional and risky for an industry mired in perennial habits. Some see brand equity as a solution to the bias problem for offsite construction: In acquiring a large portion of Stack Modular, a North American modular volumetric producer, Bird construction has incorporated an offsite solution to its service list. 

 

As a general contractor Bird understands the role and responsibilities of construction as a service coordinating many offsite produced components and onsite trades. Merging this integrator capacity with the speed and efficiencies of modular volumetric elevates both parties with an idealized business proposal based on their strengths. Being associated with Bird's 100-year history in the construction space, modular volumetric gains instant credibility as a relevant construction method. In turn, being associated with Stack Modular's innovative manufacturing methodologies elevates the general contractor to an agile innovator capable of adopting new business models as they become available and applicable. Uniting onsite services with offsite production in a seamless manner creates a formidable business model to develop and build projects of any scope. 

Bird and Stack Modular - brand equity

Prefabrication experiments - 455 - Dodecahedron Dwellings

In the interest of reducing production and construction costs, architects have been fascinated by simulating dwellings using geometric shapes. Along with modern tessellated patterns, the fundamental links between architecture and geometry are deep rooted; circles, triangles, golden rectangles are all part of a compositional repertoire since the beginning of a formalized academic education and earlier as vernacular building approaches used geometry to anchor buildings. Modernism’s thirst for newness emphasized geometry as part of systemic solutions with grids and modular shapes in tune with the rhetoric of industrialized construction. 

 

Buckminster Fullers’ use of the octet truss and icosahedron, Zvi Heckers personal brand of modular geometry along with Gerard Caris’ deployment of regular pentagons all undertook the challenge of demonstrating efficient spatial organizations from unit-shapes.  Caris’ aggregated dodecahedrons embraced the same conceptual undertones of the megastructure movement along with modernism’s obsession with manufacturable units into an exponential multiplication of unique housing landscapes. 

 

Dodecahedrons are composed of twelve regular pentagons with 5 equal length segments. The Pentagonism explored by Dutch artist Gerard Caris in the 1970s as sculptural form, patterned the same massing geometry as architecture. Juxtaposed sliced half solids could be set on any flat surface and used as an autonomous shelter or clustered in a radiating pattern of rooms by matching their planar surfaces. Unique in their underlying shapes, Caris' experimental models remained conventional in their planning articulated to a two-dimensional separation of day and night spaces which filled the volumes without exploring either their spatial or geometric potential to develop innovative interior architecture.

 

Marginally applied, these geometric experiments showcase a representational obsession of fractal and serial artistry. The seemingly simple to arrange shapes and their mathematical connectability proved awkward articulated to overly complex juxtaposition details suggesting spaces that are difficult to inhabit. Unlike Fuller’s octet truss based on equilateral triangles to simplify a structural complexity with a robust shape, pentagons implied a flatness and planar fields that when constructed with conventional means bring no structural advantages and remain an experiment in textural form rather than structural or architectural form. 

Half dodecahedrons set flat on any site

 

Prefabrication experiments - 454 - Digital paradigm shift

 

Digital design and construction have initiated a new paradigm in building production. While edifices remain prototypes, generally built only once, making them in a virtual environment before assembling them onsite, makes it possible to identify and eliminate costly coordination and systemic entanglement errors that would habitually be addressed on site. This type of digital twin approach facilitates prefabrication and potentially transforms conventional building processes by placing all stakeholders, including manufacturers in the planning stages of a project. A significant shift from the design-bid-build model toward an integrated collaborative and streamlined process from design to fabrication and to assembly, virtual coordination is also seen as a driver for increasing factory production in architecture as it lines up with DfMA and Lean management principles. 

 

Lessons learned from past paradigm swings in construction have often touted the promise of prefab but offsite construction’s share of construction remains marginal. Today, proponents are demonstrating the inflection of a personalized design and fabrication process which include manufacturing parameters from design genesis. Subassemblies for floors, walls, mechanical systems, and other building requirements can be produced as parts or as complete large-scale chunks to be packaged, sequenced and delivered for assembly onsite. Contingent to greater preparation, precise models and a deeper knowledge of supply chains, lead times, manufacturing challenges, reduces waste at every step.  Working together on a virtual model stakeholders can relate to issues from design to construction management in real time, agreeing to any reworkings before anything gets put together. 

 

Digital twins introduce a novel way of looking at prefabrication which is very different from industrialized construction of the past as each project remains a prototype using factory production to make things better, in a controlled setting and on time without the seriality of mass production. While many feel that this type of virtual construction will lead to greater offsite uptake for the construction industry, it does not address the fragmented industry and will not necessarily lead to lowering costs. Perhaps this new take on custom prefabrication will, however, make it a far less scary word for sensitive architects worried about affirming their creativity. 

 

Bryden Wood's digitally informed façade kits

Prefabrication experiments - 453 - Prefabricated Aluminum Shell Houses (1951)

 

Achieving a maximum form/space relation with minimal resources was a fundamental topic in modern dwelling design along with its potential industrialization. Vaulted Quonset huts, panelized A-frames, shotcrete sprayed domes, all symbolize the quest for an optimal tuning of materials with shapes to assemble walls and roofs, seamlessly. Vaults, shells and simple triangular trusses can be built with any material but mass production and later the military industrial complex underwrote innovative use of plastics, plywood, steel and aluminum. All progressed during the first half of the 20th century and paralleled architectural modernism's aim of maximum affordability. Using resistant geometries to create coverings coveted by many modern architects required materials with the capacity to be shaped while maintaining their strength and durability. 

 

Aluminum perhaps above all represented the newness and lightness associated with aviation. Combined with simple aerodynamic forms, its possibilities inspired a construction system, designed my modern master Jean Prouvé : a small scale airplane wing deployed as a curved shed roof. Outlined through industrial collaboration with aluminum manufacturers in France, Prouvé presented the «shell houses» or the Maisons Coques at the 1951 Salon des arts Ménagers, an exhibit showcasing advances in domestic functions, trades and crafts. The small houses were made from stressed skin aluminum elements curved to create a type of awning component supported on either end by similar vertical stressed skin bearing walls. 

 

Employing the architect's usual 1-meter grid, the panels, composed in a linear arrangement, for walls and roofs could simply be juxtaposed, assembled and later disassembled. The process could be industrialized using the same technology Prouvé had deployed with architect Bernard Zehrfuss for a shed saw-tooth roof structure for The Mame Printers at Tours. The solar and light reflection potential of aluminum stressed skin surfaces was valued for both exterior and interior applications. Vertical louvres used as shades positioned on the sun-facing wall conceived as moveable wings also provided an example of  Prouvé’s talent for shaping lightweight metals, into industrializable components. This same system was used for building schools as it was basically just a wide spanning shell for any architectural space. 

 

Shell Houses in front of exhibit venue photo  https://strabic.fr/Jean-Prouve

 

Prefabrication experiments - 452 - Vaulted concrete innovations

Modern materials and methods revolutionized building construction. Reinforced concrete specifically evolved though many varied experiments during the 19th century into a material associated with multi-unit residential typologies as the artificial stone is composed of widely available resources, it’s also solid, durable, affordable, and fireproof. These characteristics make it the most used man-made substance on earth. Its important advantages are somewhat offset by a high weight to span ratio. With an approximate mass of 2400 kg/m3, concrete slabs, beams, columns, and other components contribute to structure’s significant dead weight. 

 

Inspired by Gothic vault stone fan or rib spanning systems, Vaulted AG’s cambered concrete floors employ similar geometric lines of force to reduce material use and capitalize on concrete’s compressive strength. While this type of ribbing used in waffle slabs or onsite produced void slabs is a first step to weight reduction, vaulted slabs exploit curved geometries to further increase structural efficiencies. Vaulted AG makes it possible to assemble efficient floor systems from industrialized parts that are bolted together to facilitate their assembly and disassembly. The arched voussoir-like fragments support lightweight floating mechanical floor plates shaping an open void network for distribution ducts, piping and other systems.  The vault’s extrados surface is hidden within the floor composition, while the intrados creates a beautiful gothic-like ribbed arched ceiling. Vaulted AG is a spinoff from research undertaken at the Block Research Group of ETH Zurich by professors Dr. Philippe Block and Dr. Tom Van Mele. Their prototypes were first exposed at the Venice biennale in 2016. 

 

A typical prototype square floor grid is assembled using 4 irregular pentagonal fragments supported by corner columns. An 8-sided central square concrete compression component locks all elements into place akin to an arch's keystone. Each pentagon’s ribs radiate from a thick intersection at the column junction and angled toward the central keystone exploiting a symmetrical arrangement. Perimeter tension members resist horizontal loads. According to inventors, optimizing compressive forces makes it possible to employ 80% less steel and 70% less concrete in a floor composition 65% lighter than a conventional one. Responding to the basic structural idiom of maximum span with minimal materials Vaulted AG revives historic building strategies to further modernize concrete construction.  

Floor system prototype

 

 

Prefabrication experiments - 451 - Micro-units designed for adaptive reuse

 

Adapting vacant, underused, neglected commercial buildings to respond to the affordable housing crisis can potentially be to today’s procurement challenges what the mobile home and cheap prefabs were to interwar and postwar 20th century housing production. Intensifying use of deserted central neighborhoods also leads to less sprawl revaluing derelict spaces. Many have suggested that adapting existing buildings to new functions is complex and costly, even arguing that new construction is cheaper. Considering its complicated logistics redeploying existing infrastructure offers environmental benefits by reducing, reusing and recycling components and materials.

 

Implanting systems for private kitchens and baths can certainly be expensive and structurally complex as most commercial building floor plates were not designed to service multiple flat layouts. Imaginative co-living patterns provide opportunities for sharing services; appartements can offer autonomous private spaces with wet core services placed to be shared among many occupants, reducing mechanical distributions. This type of micro-unit community was projected by London firm SHED. The tiny units can easily be slipped into any building. The no frills living standards offer a safe and private place to live, sleep and work. They also help revive buildings that otherwise would slip further into disrepair. 

 

Tim Lowe, an architect from Studio Bark, the founder of the SHED project sees their approach as a win-win low rent strategy. Conceptually, the integrated furniture units are a type of Ikea kit framed within a streamlined supply chain; The modular volumes’ components can be produced serially to efficiently distribute low-cost micro-dwellings.  All elements including wall panels are designed to be assembled or even disassembled using a mallet and a screwdriver in a day. Insulated for acoustic and thermal comfort, interiors would include a small space for working along with a closed area for sleeping. All other dwelling requirements are shared.

 

In a typical central core office layout, the central core could be adapted to include common kitchen and baths using the existing vertical ducts with the living pods being distributed freely on the open floor plate. While admittedly not a total solution to solve housing shortages reusing existing infrastructure does substantially diminish massive material extraction required by new edifices.  

Moveable unit in an existing building