DECEMBER -2021CONSTRUCTIONBUSINESSREVIEW.COM8In my 20 years as a structural engineer with Arup, I've been lucky to work on a range of projects that challenge construction industry conventions. In 2009, I was asked to join one such project. A developer had hired a team to design a volumetric modular system suitable for implementation on an unprecedentedly large-scale, fora 32-story apartment tower in Brooklyn, New York. Despite encountering some challenges along the way, the viability of the systems used on that project eventually proved out. I've been a true believer in the potential of volumetric modular ever since.In my opinion, no technique has more potential than volumetric modular to bring the efficiencies of the manufacturing sector to the construction industry. Deployed at scale, it could help answer some of the most pressing challenges our cities face, from shortages in affordable housing, to the scarcity of skilled construction labor and the resulting escalation in conventional construction costs for large urban projects. When we started the Brooklyn tower ten years ago, our team assumed, as many still do, that the biggest challenges we'd face with volumetric modular would be technical. How could we make a modular system withstand hurricane force winds in a high-rise configuration? How could we develop fire protection strategies that met code compliance standards without UL listed assemblies? How could we connect modules together on site without ruining the finishes that had been so painstakingly completed in the factory? All these technical challenges were actually solved with relative ease. We found that the real obstacles to more widespread adoption of volumetric modular are not technical. Instead, they have to do with the scalability of production capacity and the incompatibility of standard procurement processes with the needs of modular.Modular manufacturers are currently well set up to deliver single family homes, 2-5 story student housing, workforce housing, military barracks, and other relatively small-scale projects. Many of these projects lend themselves to the use of dimensioned lumber structural modules. However, lumber modules aren't code compliant for projects over six stories or those with specialized program types that necessitate the use of non-combustible construction materials. You might assume then that the higher cost of steel modules is the main obstacle to adoption of modular techniques for larger urban projects, but, in fact, we found that the costs of producing and erecting a steel modular structural system were comparable to the costs of a site-built concrete flat slab system. Instead, it is the constrained production capacity of manufacturers that limits the size of projects considered viable for modular.Consider that a single crane can easily set 10 or more modules a day, and 100 modules in a matter of weeks, while most modular fit out factories are set up to produce only 2-4 steel-framed modules per week. The current level of output is fine on a smaller job (<~40,000sf), because the factory can begin producing modules about the time site work starts and have them all ready within 4-6 months by the time the foundations and plinth are complete. But when projects get significantly above 40,000f2/100 modules, most modular suppliers start to encounter difficulties. The number of modules steeply increases, but the time required to complete foundations and site work stays roughly the same. Given sufficient lead time, modular manufacturers could, of course, produce the required number of units, but IN MYOPINIONSCALE ­ THE KEY TO UNLOCKING MODULAR'S POTENTIAL FOR HIGH DENSITY URBAN PROJECTSBy David Farnsworth, Principal, Arup
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