At the left-hand end of a short shelf of my books on prefab is House Out of Factory by John Gloag and Grey Wornum, published in 1946 in the UK. It examines all the values of prefabrication.

The 30 books to the right, published in the 70 years since, all have identical arguments, albeit with more photos on better paper with more modern fonts. But identical in argument.

Tone on Tuesday: On Prefab

But prefab has never taken off, at least in Australia. How is it that something that most architects think is a great idea has proceeded so slowly? At first glance it has massive upsides. Quicker, better, safer, greener. Why wouldn’t you make every building that way.

Let’s unpack each of those ideas of prefab’s upside.

Firstly, prefab speeds up the time taken for construction: the main body of the building can be built in a factory whilst the footings and infrastructure are done on-site at the same time. And time is money, no more so than in construction.

Secondly, the quality of the workmanship will always be better in a factory, with stable conditions, than on a site, where it's open to the weather. Albeit heavy materials like concrete and brick can only be laid on site.

Thirdly, it is safer for workers to build in a factory, on a stable floor, not at height and with better safety controls than on a site. The workers, and particularly materials handling, for rooms or units destined for upper levels are far easier to manage if they are first assembled on a factory floor. Lunchrooms, toilets and first aid rooms are all better when permanent in the factory than on a muddy site.

Lastly, and most importantly now, it is greener in many ways: material usage and inputs are better controlled and waste can be more efficiently recycled; transport is reduced: all the subbies tools are in the one secure place rather than being driven all over the city in vans and utes; workers can catch public transport to a convenient location, rather than driving every day to various sites.

These positive ideas have remained constant for 70 years and yet prefab is still niche and not mainstream, particularly in Australia which has one of the lowest proportions of high-quality prefabricated buildings in the western world.

Where prefab flourishes in Australia is at the bottom end of the market: site sheds, mining dongas and transportable homes in mobile home parks (which are never mobile). In the last 10 years some niche contractors have set up in in Melbourne, designing and building higher end homes, but the NSW industry, located around Gosford, remains focussed on the cheaper and recreational market.

More promising for prefab at scale are the fledgling attempts to make prefab for medium to tall apartment buildings: Unitised Building (UB) in Melbourne, founded by architect Nonda Katsalidis and others, has built 57 apartments in 63 modules in 11 days which you can see here: (https://www.youtube.com/watch?v=Fz2t8JUI5V4).

Units can be made totally sealed, such that they are only opened by cutting protective plastic wrapping once every unit has been craned into place, for instance in motels developed in Sydney by MBS (Modular Building Systems). Theoretically they can have linen on the beds and cutlery and crockery in the drawers: the entire room is ready to use once installed.

Unlike Australia’s understanding of prefab being a cost-driven alternative, in the US prefab is promoted to build complex, finely wrought homes which would be impossible to achieve on a site-built construction, and they come with construction costs to match. Architects such as Michelle Kaufmann and Marmol Radziner have played a leading role, but the complexities of financing, the limited number of high-end clients and the global recession drove the early innovative players from the industry. Living Homes in Los Angeles however continues to build an expanding number of exquisite high-tech homes, as it has over the last 13 years (https://www.livinghomes.net).

Prefab start-ups often imagine that shipping containers are an easy entry point, given that containers are made in high-strength anti-rust Corten steel. They resist extreme weather and can be stacked six to eight high, essential characteristics for prefabrication. But they are a terrible dimension for rooms being less than 2.4 meters in width and either 6 or 12 meters in length. Great if you are looking for student dorms, backpacker or emergency housing (https://www.theguardian.com/cities/2015/oct/09/living-steel-box-shipping-containers-future-housing).

Not so good for regular housing though. One of the best exploratory firms, Logical Homes in LA, gave up trying to build using shipping containers when the twin problems of needing to cut so much of them up to make decent spaces, and authorities requiring unreasonable certification (to drive them containers out of the market), made the venture untenable. Environa Studio in Sydney discovered the limitations too when they built a house of the future for the Year of the Built Environment as a display home at the Sydney Opera House. Except for the strength of the four corners, it would have been better to start from scratch.

One of the problems with all these prefab solutions is that you have to move a lot of air: architecture is space and moving space is cumbersome and expensive. What if you could prefab just the container parts, and not the contained? Make whole parts of the building and then ship those ‘flat-packed’ to site.

This is an extension of the current use of small factory-made components such as windows, doors and joinery into larger elements that can be trucked flat to site and assembled by crane and bolted together. You can make entire walls with windows, large areas of floors or the compact complicated rooms such as bathrooms. Did someone say Meccano?

This is the principle behind ‘flat-pack’ IKEA (who are now doing prefab houses BTW). But what material can you use when heavy weight concrete, terracotta, brick and block – the staples of Australian construction – are not viable? The answer is CLT – cross laminated timber. Well known in Europe, it has now arrived in Australia via NZ company X-Lam with a factory in Wodonga, and a CLT fabrication company developed by Lend Lease.

CLT is essentially giant laminated plywood, with 40mm+ plys making up 200-300mm thick componentry, pre-routed and pre-drilled, ready for assembly by the use of steel brackets and bolts. Using CLT Lend Lease have built ‘Forte’, an experimental apartment building in Melbourne, the ‘Library at the Dock’ by Clare Design and a low-rise office building at Barangaroo by Tzannes, now exploring many innovative uses for CLT. As time goes on, more and more of the timber surfaces are revealed in each building.

Where to for prefab? Most likely houses and small residential will continue to be made in whole units, and CLT will be increasingly used, but the most interesting developments will be in automation of components that are ‘assembled’ rather than ‘built’. The key guide here is The Machine that Changed the World, a 1991 book by MIT based on a five-year study of the future of the automobile. The essential story is how Toyota invented a whole new way of diverse-sourced and high-quality assembly, replacing the old idea of a production line.

Prefab has been seen the same way since House out of Factory in 1946, but this is a radically different approach of having separate factories making key components that go together precisely in a just-in-time framework to make a whole building in less time but with unheard-of micro tolerances and high quality. Just how that works has to be the subject of a future instalment.

The views expressed are solely those of the author and are not held or endorsed by A+D. Disclosure: Tone Wheeler is the principal architect at Environa design mentioned above, and consulted for a brief time to Lend lease on CLT.

Tone Wheeler

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