Prefabrication experiments - 522 - Rebel DfMA - The «Over-the-Wall» Problem

Each major advance in manufacturing techniques spawned experiments for bringing the same efficiencies to building construction. DFMA - Design for manufacturing and assembly is a management methodology related to breaking down the barriers between designers’ visions and fabrication parameters. Cited as the «over-the-wall» problem, authors Boothroyd, Dewhurst and Knight (1983) from the industrial design field, described a framework to reduce waste as well as to streamline tasks through an optimized production process synchronizing supply chains and design with production criteria. Reducing the number of pieces and parts in an assembly is the conceptual basis for this lean industrial design strategy. 

 

Recently conceptualized for building construction, DFMA or construction-DFMA rewires conventional construction practices through maximised use of offsite manufactured sub-assemblies to facilitate the onsite erection of any type of edifice harnessing the already well documented advantages of prefabrication. Platform DFMA (another conceptual variant) offers further gains by centering the design of diverse buildings on similar components and their shared details. 

 

Rebel DFMA is an American company with a value proposition articulated to digital modelling as a fundamental part of an integrated DfMA process. Virtual modularization, high-level-of-detail modelling, streamlined shop drawing generation along with the production of onsite user-friendly assembly manuals outline the company’s services. The highly detailed models encapsulate segments, modular and coordinated parts that can be contracted to factory partners and delivered just-in-time to building sites to be put together according to precoordinated processes. DfMA brings the designers to the factory floor before design so that initial design ideas account for their manufacturability. 

 

DFMA requires advanced planning and systematization of tooling, materials, methods and supply chains making this process applicable to any building. BIM has provided an inflection point for digitization to reform construction. It has also provided a wave of interest for new prefabrication theories to emerge. Although DFMA certainly provides a lean framework, it can be argued that it has become just another catchphrase for shedding the archaic connotations associated with prefab, manufactured building or industrialized construction. 

Image from Boothroyd, Dewhurst and Knight (1983) 

Prefabrication experiments - 521 - A Third Emerging Business Model - Project Specific Prefab

 

Industrialized construction is and has always been linked to standardization and repetition. This was undoubtedly the case for post-war, low-cost construction strategies that sought to leverage mass production. Previous blog posts examined vertical integration (post 518) and digital integration (post 520), both harnessing some type of replicable process or product parameters to scale and regulate factory resources. A third emerging business model examines offsite construction not to repeat projects but to mitigate some of the coordination concerns and conflicts in conventional construction; Onsite construction continues to be hindered by lagging productivity linked to systemic entanglement, labour shortages, rising management costs, and overall trade fragmentation. 

 

A growing number of general contractors are exploring the promise of digital processes and tools like BIM (Building Information Modelling) to facilitate factory production for preselected, agreed upon and coordinated chunks of singular buildings. They aim to synchronize design with project management, trades, materials, their delivery and assembly onsite to avoid the costly errors associated with traditional builds. Flying factories, multi-trade coordinated contracts for distributing responsibilities, and near-site prefabrication are all variations of this virtual design and construction business model. Project components and their interrelationships are precisely outlined, modularized or panelized, as large sub-assemblies fully coordinated in an up-to-date, well-equipped and controlled setting. 

 

Project-specific prefabrication is less concerned with replicable standards than with repeatable processes, making it possible to design and construct unique buildings. Digital coordination and file-to-factory-to-site management propose the same overlapping of tasks that speeds up construction while resolving coordination bugs in advance of their discovery on site. 

 

Age-old narratives associated with factory production are being swapped for the high-quality potential of a general contractor / integrator managing on as well as offsite elements along with their systemic synchronization, attributing them to sub-contracted trades and producing them through manufacturing methodologies.   Multinational builders like Skanska and Turner Construction are adopting similar approaches redefining their role of management specialists to include lean manufacturing and efficient onsite assembly facilitators to prefabricate everything from mechanical modular rooms to hospital bed walls and everything in between. 

Temporary production facility set up by Skanska for the Miami Valley Hospital

Prefabrication experiments - 520 - Digitally integrated business model

The introduction of CAD and eventually highly detailed modelling in architecture and construction has favoured the virtual planning of buildings ensuring the proper alignment and disentanglement of their systems. This digital-twin approach outlines a file-to-factory workflow that is driving a configure-to-order business model in offsite construction. A common interoperable CAD-to-CAM methodology decentralizes production offering multiple manufacturers in different contexts the opportunity to make and deliver project components where they are needed according to pertinent locus-based supply chains. 

In lieu of the heavy upfront capital investment that comes with managing a traditional vertically integrated factory with its design to manufacturing supply chain, a company can instead present a design system or platform (hardware and software) conceived for configuring projects in line withmanufacturing affiliates. Project FROG founded in California (2006) articulates this business model by harnessing the power of multiple suppliers and factories to deliver FROG-designed parts and processes specifically for classrooms. Once architects have designed the component-basedbuildings, FROG partners receive orders and through a synchronized design-to-manufacturing organization, supply FROG recognizable projects in any serviced setting.  Founded on digital cloud-based tools and their process integration, this contract manufacturer model multiplies capacity as IP and purchasing parameters can be shared among a network of factories. 

The now defunct Canadian company BONE Structure, one of the most advanced, digitally integrated home builders in North America while it operated, used a similar M.O. Projects were designed and documents prepared for manufacturing and then transferred to partners who fabricated site specific kits-of-parts. The cold-formed steel structure and other building parts were supplied by licensed fabricators. The system's uniqueness was not linked to a central factory but rather to a digital platform methodology identifying BONE homes from a central architectural direction and production framework. While this model reduces costs associated with a vertically integrated factory, it requires maintaining and cultivating partnerships with a stable pipeline of projects to maintain supplier loyalty and a best price management model. 

ps. Bone structure closed in December 2023, after the tragic death of its owner Marc Andre Bovet who was not only a great innovator but also a great friend.

Contract manufacturing decentralized production

Prefabrication experiments - 519 - Modlines

 

Modular volumetric construction is characterized as both a quick and efficient way of erecting multiple building types with scalability linked to repeatability. Residential units, hotels, student lodging, tract housing that can use similar designs from one project to the next offer important exponential procedural potentials for applying mass production principles to stacking factory-produced boxes. Chiefly determined by transport criteria which can vary according to cities and countries, factory-made 3d modules can be aligned, aggregated and multiplied as long as loads are rigorously controlled through vertically aligned bearing elements.

 

Aligning sections, corners and modlines is the rudimentary assembly strategy that regulates an efficiently engineered design-to-manufacturing process, as lining up boxes both horizontally and vertically simplifies construction and avoids costly position-based structural modifications, often proposed the name of architectural variability: angles and cantilevers are two design elements that require module specificity and complexify the production process’ necessary replicability from one module to the next. Variations rapidly increase costs and limit the common-sense approach. Organizing repetition in these elements can also help reduce manufacturing-to-onsite stitching headaches. 

 

Projects with a greater module consistency factor will streamline supply chains and production, conceivably leading to reduced costs. Showcasing or camouflaging modlines is therefore the basic design question. Showcasing modlines and boxes often enhances the connotations limiting greater uptake of modular volumetric construction as buildings are qualified as normalized or too standardized lacking architectural personality. Modlines are the vertical and horizontal geometric contours where the boxes meet and are attached; Boxes’ surfaces can create some structural redundancy as they increase material use when compared to conventional onsite systems.

 

Simply stitching these modlines on site creates an architecture that speaks to modular volumetric while other strategies include stitching and covering these lines by completing cladding on site to erase any visual links to the production process. Architectural design whether conventional or modular is a function of revealing or hiding a project’s underlying construction processes, modlines can be used as devices to nuance, illustrate or camouflage these architectonic ideas.

Modlines and modular sequencing

Prefabrication experiments - 518 - Business models: vertically integrated - configured-to-order

 

The marginal application of comprehensive factory-assembled and industrialized building systems has taught us that while mass production increased efficiencies in other commercial sectors, architecture and construction's resistance has been bogged down by values based on artisanal singularity. These fragmented processes have led to the making of unique, original, and beautiful public buildings and should be valued for this - even with all the underlying challenges.  However, when it comes to building types that are highly repetitive - collective housing blocks, primary schools, and light commercial properties - it would make sense to harness some of the economies that come with mass manufacturing ecosystems.

 

Harmonized supply chains, bulk material orders, systematized management, pre-assembly in a controlled environment, and reduced waste are just some of the elements that could help rationalize a well-conceived manufacturing-to-building process. Further, current digitally integrated value propositions are evolving from repetition toward variable organizations generated from a set of predefined parameters. Certainly not new in the industrialized construction space, modular volumetric manufacturers are endeavouring to espouse a customizable stream based on skeletal or stick-framed prisms directed toward a large number of potential configurations. The configured/engineered-to-order production methodology is reforming the manufactured house on a steel chassis model defined by predetermined designs that came to symbolize factory housing. 

 

Architects can work closely with manufacturers to personalize designs fitted to modules’ strict dimensional criteria and a company's standards. Balconies, hallways, and any other type of required space can be built into the overall dimensions, put together in the factory, delivered and set on or attached to adjoining modules. Completed to a high degree indoors, on-site work could conceivably be limited to infrastructure and mechanical connections. Modular volumetric companies, for the most part, follow a vertically integrated production model. Volumes are pre-assembled according to a network of suppliers from raw components to complex sub-assemblies. Windows, doors, flooring and all other required parts are purchased in bulk, organized and sequenced in the factory with assembly line precision. This integrated purchasing to production process replicates just-in-time production framed by increased agility to respond to client demands.

Z-modular steel framed modular platform

Prefabrication experiments - 517 - Three «Platform Oriented» Business Models

Ways of doing business in offsite construction are being reformed by digital practices and platform thinking percolating into the construction sector, both fostered by advances in parallel industries. The highly repetitive, standardized production methodologies that accompanied the Second Industrial Revolution (mass production) introduced product families and design catalogues with little to no variability. Mobile home or kit-of-parts house manufacturers proposed products within a set of constraints and components.

 

Today, the Fourth Industrial Revolution (mass customization) is providing the prevalent configured-to-order ideology of variable architecture from a library of digitally organized parts. Current literature points to three business models in the industrialized construction field: the first is vertically integrated, the second is a digitally driven delocalized production model, and the third is related to spinoff factories set up to facilitate an integrated process for the conventional general contractor. 

 

A design platform is the overarching umbrella theory infiltrating all three where chunks or sub-assemblies share similar components, criteria and parameters. The modular volumetric producer, spawned from the evolution of the manufactured housing company is a suitable representation of the vertical integration model. Planning and production are articulated to a dimensionally coordinated prism - the basic chassis (the platform) of any modular project. Supply chains, design possibilities and project management are tuned through a central company which coordinates production from bulk material orders to delivery along with building assembly. 

 

Both the second and third business models are defined by a delocalized process and precise virtual design models that can be modularized and spilt into parts made in non-proprietary factories which are then delivered to site. Supply chains can also be comprehensively managed by a core company, however there is not necessarily one centralized location for production – projects are engineered to specific requirements including place, regulatory frameworks and architectural variability. This type of kit-of-parts approach configured or engineered-to-order relies on standardized details, harmonized supplier and core company relationships, flexible integrated project delivery methods, and upfront planning. These are all geared toward the assembly of interrelated parts common from project to project - simplifying coordination, supported by efficient rationalization and creating economies of scale based on sharing elements and methodologies.   

Three business models: Left: Modular volumetric centralized production (Champion Homes); Center: Digital platform delocalized production (Project Frog); Right: Flying factory for bespoke building (Skanska)

Prefabrication experiments - 516 - Predictable demand - scaling capacity

 

As the housing crisis deepens, shortages are accumulating, construction costs are rising and offsite approaches are being encouraged at policy levels to increase productivity in construction. For prefabrication and industrialized building systems more specifically to be adopted and work on all cylinders, demand must be systematized as a streamlined pipeline of similar types to enable manufacturers’ existing methodologies to be deployed successfully. 

Innovative application of technologies within the industrialized construction space, panelized or modular is difficult as current project demand, which is required to plan a company's viability are simply not at predictability levels conducive to adopting or investing in production strategies that bolster capacity. Government programs in certain countries are directing initiatives to frame both current and future demand guaranteeing long-term commitments giving manufacturers confirmation that any investments will not be in vain; stability encourages both growth and technological reform.

For the manufactured housing sector this type of secure demand is critical as profitable fabrication of homes in a factory is based on continuous supply chains and normalized requirements. Promoting specific building systems like modular volumetric building with stacked standardized units has proven challenging as in the single-family dwelling market - the sector's bread and butter at least in America - pipelines are articulated to simpler conditions when compared to the collective housing blocks.

Collaboration with professionals, code requirements, energy metrics along with performance criteria, logistics and project management in dense urban areas are just a few conditions that showcase collective blocks’ complexities in relation to business models derived from single-family dwellings. Without predictable orders that provide the capacity to study, implement and deploy integrated manufacturing processes, most companies lack the financial robustness and resilience to support fragmented project orders. Automation, in particular, has been difficult to implement, at scale, in housing manufacturing where demand doesn’t justify substantial upfront investments. 

Pipelines for conventional construction are developed on a project-by-project basis and are not conceived for scale. They are geared toward an imagined / perceived bespoke quality. Successful application of industrialized construction points to a reformed model of mass production where stability in demand supports a customizable uniqueness through scalable systems.

Toyota Homes factory production - capacity of 5000 units per year