32 | SUMMER 2019 ADVANTAGE STEEL Helping to realize the potential of prefabricated prefinished m STRUCTURAL STEEL By Tom Greenough and Matthew Smith, Entuitive FEATURE INTRODUCTION Prefabricated prefinished volumetric construction (PPVC), sometimes referred to simply as modular construction, is a process whereby buildings are planned and designed to allow for discretization and standardization of 3D volumetric structural units that allow for efficient off-site manufacture and rapid on-site assembly. The fabrication and manufacture process results in a partially to fully fitted out module built under controlled conditions. Prefabrication in the construction industry is not new;curtainwallmanufacturershaverealizedthe benefits of off-site construction for many years. Repeatable, labour-intensive components of larger buildings, such as washrooms, have also enjoyed the benefits of off-site construction1 . These non-structural modular units are then placed within a site-built structure. Purpose-designed and built pre-engineered buildings have also been around for centuries. The total prefabrication of large contemporary buildings is seeing increased attention by clients as they look for opportunities to reduce project schedules and achieve a greater degree of cost certainty. The ability for the construction industry to respond to this opportunity is made possible by advances in Building Information Modelling (BIM), investments in prefabrication facilities, and modern building materials and methods. The benefits of this approach to building construction are reduced construction time (Figure 1), reduced cost, consistent quality, increased worker safety, and a cleaner, quieter construction site. The ability to manufacture the modules concurrently with on-site foundation and podium work is one of the huge advantages of modular construction which allows for significant time savings. The construction industry is often regarded as ripe for innovation2 , with PPVC being one such opportunity that can improve productivity3,4 while keeping a workforce increasingly short of skilled tradespersons engaged. PREFABRICATEDMODULARCONSTRUCTION The design and construction of modular buildings comes with unique challenges compared to site-built construction that all project stakeholders must be aware of for the project to be a success. These peculiarities are outlined below. Project Team Organization The fragmentation of the design and construction process has limited the effectiveness of collaboration and often resulted in an adversarial construction culture much to the disadvantage of all stakeholders. Furthermore, buildings are often conceived as unique projects every time and employ temporary teams, unlike the manufacture of consumergoodsinotherproductionindustries. The advantages ofa consistentteam havebeen realized by some design-build entities who continually engage with the same consultants andsubcontractors.Bycontrollingtheworkflow in much the same way, PPVC manufacturers can keep a consistent team. This requires early engagement of a modular manufacturer and this aspect is often regarded as essential to project success. Once engaged, the modular manufacturers may manufacture for a general contractor or contract directly with owners to provide modular solutions and fulfill the role of general contractor. Modular manufacturers may also have internal architects and engineers that can assist throughout the design and manufacture process. Design Considerations The decision to go modular needs to be made early on (schematic design or earlier) to ensure the building is developed with FIGURE 1: Possible schedule savings with modular construction. Adapted from Introduction to Commercial Modular Construction by Modular Building Institute.