For many architects, and their customers, architectural prefabrication implies a rational and systematic approach: off-site construction, precise and standard material systems, production efficiency. The character and benefits of prefabrication are most commonly associated here with the design-to-manufacture cycle, with less study—or at least less consideration—of prefabrication’s impact on the project lifecycle.
In this paper, we turn our attention to the potential of prefabrication to enhance material and spatial flexibility—to rethink our homes as adaptable systems that can be refined and evolved over time. From the early design testing and co-design potential of 1:1 architectural prototypes to consistent manufacturing tolerances, interchangeable units and assembly systems, and conceptualizing the architectural whole as a composite of modular units, prefabrication processes and products can be temporary or make longer-term relocation easier. Such an approach can allow for cycles of uses and users of a home over the life of the building and can be particularly beneficial for people experiencing temporary changes in housing needs. And while the potential benefits may seem obvious, they have yet to be widely applied, at least in Australia. Two current projects in Brisbane illustrate the possibilities.
The flexibility of modular prefab homes is evident in the work of Brisbane architects Vokes and Peters, who have worked with prefab contractors for more than a decade. The latest collaboration is with the construction company Blok Modular. Stuart Vokes explains that his contribution to this collaboration includes “the development of single family home floor plan typologies that will contribute to an a la carte menu of standardized floor plans” for the company. He highlights the possibility for evidence-based investigations through ready-made methods that can be achieved through iterative experimentation. His house designs for Blok are a matrix of floor plan drawings that represent “an empirical study of ready-made typologies (similar to the entomologist’s pinboard) made in a systematized and controlled manner of construction”.
Chapel Hill House in Brisbane’s western suburbs is one example of the 25 buildings that resulted from this collaboration. The project was driven by the client, who is an occupational therapist, and their desire to showcase age-appropriate housing on site. The house consists of seven prefabricated modules that wind around a central courtyard. The uniformity of the size and scale of the modules and the structural design – which entails no load-bearing internal walls – gives the home great adaptability. The home is designed and built to respond to the changing needs of its residents. Modules can be added or removed to increase or decrease floor space, while the interior of each module can be easily renovated to suit individual requirements.
Another example is a three bedroom house in Yarrabilba, south of Brisbane, designed by architect Luke Rowlinson to the Platinum standard of the liveable housing guidelines. 1 Under the auspices of Lendlease’s national sustainability manager, the house was designed with a self-assembly system 2 that minimizes on-site construction time and allows for spatial and material customization. The construction includes a panel system and a frame made of metal. Rowlinson explains that for pre-engineered systems to function on site, a high degree of accuracy is required early in the project – for example, sitework, foundations and slabs must be built to exact dimensions.
Prefabrication is a design methodology that comes under the umbrella of Design for Manufacturing and Assembly (DfMA), an approach that appropriates manufacturing processes and technologies from the manufacturing industry. Prefabrication involves manufacturing tolerances that provide greater accuracy for the build results. The fact that dimensions and tolerances are tightly controlled, creating verifiable build volumes, makes it easier to modify or add to prefabricated dwellings over time. They also help meet accessibility requirements by building ramps, openings (e.g. doors) and especially thresholds where floor coverings change. Achieving “zero thresholds” is particularly difficult with on-site construction methods, but off-site prefabrication exhibits a level of control that cannot be achieved on-site.
Designing barrier-free living space is about more than meeting technical standards; It’s also about creating well-designed accommodations that people can be proud to call home. Working with prefabrication allows for ongoing consultation and co-design with clients, allowing them to see and experience a home design before it is sourced or delivered on site. Rowlinson’s customers can view a full-size prototype in the warehouse, safely and easily test the design, and suggest tweaks or small changes. Prefabrication also encourages continuous product innovation for home construction, including the development of products that meet the needs of everyone in the market.
The circumstances of a family or an individual can change quickly, unexpectedly and at any time. Given the lack of accessible housing stock in Australia, the speed of DfMA allows machine learning processes to be transferred to the construction industry, resulting in processes that can respond quickly to sudden changes in the housing needs of families and individuals. Volumetric prefabricated housing modules can be completed in just four weeks. Pre-engineered solutions include purpose-built kitchen and bathroom pods, as well as entire new living units (granny flats) that can be co-located with existing dwellings. But while these solutions meet urgent needs, they are often only temporary measures until more suitable housing can be found. Providing housing units that are separate from the main residence is often not a comprehensive solution. Additionally, there are cost and installation issues associated with kitchen and bathroom enclosures. We need more design-driven innovation in the development of prefabricated products, and architects have an important role to play in creating better solutions for people experiencing sudden shifts in housing needs.
There are many benefits for architects working with DfMA. According to Vokes, “The prefab procurement model appears to have entered a phase of obvious relevance, with the offering of greater cost certainty, shorter construction timeframes, lower holding costs, greater control over waste minimization, a solution to alternative land tenure models, reduced toxicity and impact on local ( Site) ecology and site neighbors, asset transferability, and a timely motivation to build smaller, smarter buildings.” Additionally, the flexibility of prefabrication design and construction methods makes it a sustainable option as it adapts to changing needs of a resident can be adjusted. Prefabrication enables zero-waste or low-waste construction methods, better building standards for more energy-efficient homes, and safer construction sites. Recent changes to the National Construction Code, aimed at moving the construction industry towards a more sustainable, equitable and inclusive built environment, are creating room for innovation; the challenge is to ensure that architects are involved in the process and take the lead. A catalog of ready-made solutions – like the a la carte menu produced by Vokes and Peters and made accessible through an open-source database – could be invaluable.
— Francisca Rodriguez is an architect and research fellow at Queensland University of Technology’s School of Architecture and Built Environment.
— Kirsty Volz is Co-Director of up-and-coming design practice Toussaint and Volz and Lecturer in Architecture at Queensland University of Technology.