For many architects, and their clients, architectural prefabrication implies a rational and systematic approach: off-site construction, precise and standard material systems, efficiencies of production. The character and merits of prefabrication are here most commonly assigned to the design-to-fabrication cycle, with the impact of prefabrication on the project life cycle less examined – or at least less embraced.
In this essay, we turn our attention to the potential of prefabrication to enhance material and spatial flexibility – to reimagine our homes as adaptable systems that can be refined and developed over time. From the early design testing and co-design potential of 1:1 architectural prototypes, to consistent manufacturing tolerances, interchangeable units and systems of assembly, and conception of the architectural whole as a composite of modular units, prefabrication processes and products can make temporary or longer-term changes to housing more straightforward. Such an approach can enable cycles of uses and users of a home over the life of the building and can be especially beneficial for people who experience temporary changes to housing needs. And while the potential benefits may seem explicit, they are yet to be widely applied, at least in Australia. Two recent projects in Brisbane help illustrate the possibilities.
The flexibility of modular prefabricated housing is demonstrated in the work of Brisbane architectural practice Vokes and Peters, which has been working with prefabrication housing companies for more than a decade. Its most recent collaboration is with construction firm Blok Modular. Stuart Vokes explains that his contribution to this collaboration involves “the development of detached house plan typologies that will contribute to an à la carte menu of standardized floor plans” for the company. He highlights the opportunity for evidence-based inquiry through prefabricated methods that can be achieved through iterative experimentations. His house designs for Blok are a matrix of floor-plan drawings that constitute “an empirical study of pre-built typologies (similar to the pinboard of the entomologist) produced within a systemized and controlled method of construction.”
Chapel Hill House, located in Brisbane’s western suburbs, is an example of the 25 buildings that have emerged from this collaboration. The project was driven by the client, who is an occupational therapist, and their desire to showcase housing designed for aging in place. The house is created from seven prefabricated modules that wrap around a central courtyard. The uniformity of the modules’ size and scale and the structural design – which results in no load-bearing internal walls – gives the dwelling great adapt-ability. The house is both designed and constructed in a way that can respond to the changing needs of its inhabitants. Modules can be added or removed to expand or contract the footprint, while the interior of each module is easily refurbished according to individual requirements.
Another example is a three-bedroom home in Yarrabilba, south of Brisbane, designed by architect Luke Rowlinson to the Platinum Standard of the Livable Housing Design Guidelines. 1 Championed by Lendlease’s national sustainability manager, the house was conceived using a self-erecting system 2 that minimizes construction time on site and allows for spatial and material customization. The construction includes a panelized system and a metal fabricated frame. Rowlinson explains that for pre-fabricated systems to work on site, high levels of accuracy are required from the very early stages of the project – for example, site works, footings and slabs must be built to exact dimensions.
Prefabrication is a construction methodology that sits under the umbrella of Design for Manufacturing and Assembly (DfMA), an approach that appropriates fabrication processes and technologies from manufacturing industries. Prefabrication involves manufacturing tolerance, which delivers advanced accuracy for construction outcomes. The fact that the dimensions and tolerances are tightly controlled, creating knowable construction quantities, makes it easier to alter or add to prefabricated housing over time. They also assist in meeting accessibility needs through the construction of ramps, openings (such as doorways) and, especially, thresholds where there is a change of floor finishes. Achieving “zero thresholds” is especially difficult with on-site construction methods, but off-site prefabrication exhibits a level of control that cannot be achieved on site.
The design of accessible housing is about more than meeting technical standards; it is also about creating well-designed accommodation that people are proud to call home. Working with prefabrication allows for ongoing consultation and co-design with clients, where they can view and experience a design for a dwelling prior to it being procured or delivered on site. Rowlinson’s clients can visit a full-size prototype in the warehouse, safely and easily testing out the design and suggesting tweaks or small changes. Prefabrication also promotes continual product innovation for housing, including the development of products that meet the needs of everyone in the market.
A family’s or individual’s living circumstances can change quickly, unexpectedly and at any time. With a lack of accessible housing stock in Australia, the speed of DfMA enables the transfer of machine learning processes to the construction industry, resulting in processes that can respond quickly to sudden changes in families’ and individuals’ housing needs. Volumetric prefabricated housing modules can be completed in as little as four weeks. Prefabricated solutions include specially designed kitchen and bathroom pods as well as entire new living units (granny flats) that can be co-located with existing housing. However, while these solutions meet urgent needs, they are often only interim measures until more suitable housing can be found. The provision of living units separate from the main dwelling is often not an inclusive solution. Further, there are cost and installation issues associated with kitchen and bathroom pods. We need more design-led innovation in the development of prefabricated products, and architects have a significant role to play in creating better solutions for people who experience a sudden change in housing needs.
There are many benefits for architects working with DfMA. According to Vokes, “It feels like the procurement model of pre-built has entered a period of obvious relevance, with the offer of greater cost certainty, lower construction time frames, lower holding costs, greater control over waste minimization, a solution to alternative land tenure models, lower toxicity and impact on the local (site) ecology and site neighbours, portability of the asset, and a timely motivation to build smaller, smarter buildings.” In addition, the flexibility of the design and construction methods for prefabrication makes it a sustainable option through its capacity to adapt to an occupant’s changing needs. Prefabrication facilitates zero- or low-waste construction methods, better standards of construction for more energy-efficient housing, and safer construction worksites. Recent changes to the National Construction Code aimed at moving the construction industry toward a more sustainable, equitable and inclusive built environment are creating space for innovation; the challenge is to ensure that architects are involved and providing leadership in the process. A catalog of prefabricated solutions – like the à la carte menu produced by Vokes and Peters and made accessible through an open-source database – could be an invaluable asset.
— Francisca Rodriguez is an architect and research fellow at the School of Architecture and Built Environment, Queensland University of Technology.
— Kirsty Volz is a co-director of emerging design practice Toussaint and Volz, and a lecturer in architecture for the Queensland University of Technology.