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Inside Innovation: Potential for off-site construction is prefab-ulous

John Bleasby
Inside Innovation: Potential for off-site construction is prefab-ulous

The term “prefabrication” is used to describe many off-site building processes, such as modularization, panelization and kits. In all its various forms, the concept is gaining traction.

It’s a logical evolution for an industry that lags most others in productivity growth. A McKinsey Global Institute Report on construction published in 2017 says, “Globally, construction sector labour-productivity growth averaged one per cent a year over the past two decades, compared with 2.8 per cent for the total world economy and 3.6 per cent for manufacturing.”

Most industries rely heavily on various forms of factory manufacturing — few are as bespoke as home and ICI construction. What is holding construction back? Many feel the problem is both instinctive and cultural — a fear of change combined with a lack of knowledge.

Yet prefabrication is not new at all. Think back to the low-cost prefab homes made popular in the 1960’s and 70’s. Even the largest construction projects have included some form of pre-made componentry. After all, steel beams are not cut to length on site.

The fact is that until recently, the construction industry has regarded off-site manufacturing as a sidebar to the main process. However, with the increased digitisation of construction, from design through to execution, attitudes are beginning to change.

The potential for standardization and repeatability is most noticeable in the hotel industry. Strip away the exterior facades and one recognizes that the bare bones of the structures are remarkably similar. Global hotel chains like Hilton and Marriott have already recognized that prefabrication means a lower start-to-finish time for new projects. That time saving means “heads in beds” sooner, and a quicker ROI.

Standardized, prefabricated building components can be used successfully for schools, hospitals and office buildings as well. Finished modular bathrooms, wall and floor assemblies, and in certain cases, entirely pre-made boxes (i.e. rooms), can be lifted and literally stacked in place.

However, off-site manufacturing and onsite assembly challenges traditional building methods, blurring the lines of responsibility between design, engineering and construction. As a result, the methodology increases the importance for the early inclusion and coordination of architects, contractors and trades. For example, building envelope specialists and mechanical/electrical trades need assurance that their teams will have access to areas requiring routing and installation work.

Likewise, owners and designers must adjust their creative thinking. At some point, designs must be frozen, and components sent to manufacturing, after which changes become extremely expensive, perhaps impossible.

The solution to meeting these challenges is technology. BIM has advanced to the point that owners can consider and confirm material and finishing choices using 3D virtual walkthroughs before fabrication. Comprehensive digital visualizations of the structure can calculate the precise measurements required for prefabrication, with details handed over to key sub-trades in advance.

BIM also makes possible the modelling and pre-testing of individual components and assembled systems. And because prefabricated components and modules can be more accurately priced during the design phase, there is improved cost certainty for both contractors and owners.

In addition, prefabrication addresses important issues like safety, material waste and labour efficiency.

Simply put, the fewer workers on the work site, the lower the potential for injury. Fully or semi-automated factory environments likewise require fewer people and are therefore safer. They are also less wasteful of materials and can, in most cases, deliver higher quality components than can on-site fabrication.

Furthermore, quick on-site assembly reduces overall GHG emissions, an increasingly important consideration for the construction industry. There is less impact from weather on the building process as well, resulting in faster close-in times and more efficient labour deployment at a time of skilled labour shortages.

The 2017 McKinsey report concludes that, added together, the safety improvements and various efficiencies gained through the adoption of more advanced manufacturing processes like prefabrication could result in an overall industry productivity hike of five to 10 times.


John Bleasby is a Coldwater, Ont. based freelance writer. Send comments and Inside Innovation column ideas to

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