As technology has advanced, so have the mechanics of building. However, prefabrication—which has been increasing as of recent—has been a staple in the building community for decades. The term “prefabricated” is given to an array of buildings and fabrication methods that are manufactured off-site and then relocated to the construction site for final integration and assembly. In the case of structural engineering firm KL&A, prefabricated design is a “completely digital- and computer-driven process where [the design team] works [together with the construction team] to build complete virtual models,” explained Greg Kingsley, PhD., president and executive officer of KL&A. “Those models are used not only to create drawings but to drive the digital equipment that cuts the pieces, so it's extremely accurate. [By] building virtually first, when the pieces show up on site, there's nothing to do but set them in place.”
And when it comes to prefabrication, wood is leading the pack. “The movement towards mass timber construction is really intimately connected to the idea of prefabrication,” said Kingsley.
KL&A's current project, Platte 15, will be the first prefabricated wood-construction office building in Denver, Colorado.
Having previously built a two-story wooden office building in Boulder, Colorado, the developer, Crescent Real Estate LLC, approached OZ Architecture, Adolfson & Peterson Construction and KL&A to design and build the four-story Platte 15. “The owner perceived a value in using wood,” said Kingsley, citing the natural beauty of wood, the ease of use, and biophilic properties.
1,300 miles away in Seattle, Washington, John Morefield, AIA, architect at Jackson|Main Architecture, P.S., has been designing the anticipated Cubix Othello project. A 6-story, 85-unit apartment building made primarily of volumetric modular prefabricated wood construction on a concrete base, this project is the second modular collaboration for developer NexGen Housing Partners and Jackson|Main.
While wooden construction is more common in the Pacific Northwest, the use of prefabricated wood (in this case volumetric modular) in the Othello project goes beyond aesthetics, offering a more robust building envelope, simplified onsite construction and added environmental benefits.
While modular buildings have been around for decades, their prevalence is increasing thanks to advancing technology and a growing awareness among builders of the advantages they can offer: eco-friendly, faster, more economical construction, year-round construction and lower labor costs, higher quality finishes and minimal patching requirements along with an overall boost in project efficiencies.
Having worked with prefabricated wood for more than 15 years each, KL&A's work on Platte 15 and Jackson|Main's Cubix Othello are beautiful examples of these advantages.
Speed of Construction
In many prefabrication processes, each piece of the building is designed virtually using Computer Automated Drafting software, then wood is cut using a CNC machine. The precise nature of this technology means that every detail is perfected and expertly measured.
With prefabrication, materials are precisely designed and cut offsite according to exact technical drawings. Sections are then documented, delivered, and put together like a jig-saw puzzle.
Building in this way and with complete modular boxes can reduce construction time tremendously, with Morefield estimating they are cutting six to eight months on the site.
Craig Mitchell, Director of Innovative Solutions for the volumetric modular construction company Metric Modular, elaborated: in building 40 modular units to create the 70 apartments, his team was able to construct each suite in the factory in 17 days.
When building begins, Seattle can expect to see this mid-rise go up at a tremendous pace—the result of careful planning. “What may look like 20 days of high-flying crane antics is the culmination of years of planning,” said Morefield.
Ability to Create Complex Designs
Having previously used prefabricated wood on the intricate structure of the Aspen Art Museum, Kinglsey and the KL&A teams are aware that the limits of complexity in architectural designs can be pushed beyond conventional construction methods. “All of the complicated work was done virtually,” Kinglsey explained. “When [the pieces] showed up on site, it all just went together. It wasn't just convenient; it would have been impossible to do any other way.”
Similarly, Platte 15 didn't skirt the details, utilizing CAD and CNC capabilities to produce a design that will fit into the locale as architecture that Denver can be proud of.
Mitchell elaborated for the design of Othello. With a 40-year history of exclusively fabricating wooden modular structures, Metric Modular prides itself on creating units that lose modular construction's disparaging stereotype of the past. “[Modular] doesn't have to be limiting.”
Sustainability
“A lot of the conversation around [prefabrication and] modular [building] has been cost and time,” explained Morefield, “but I think 'greener' is a big component. The sustainability [aspect] of modular construction is already there, it just needs to be highlighted and pushed forward.”
The sustainable benefits of prefabricated buildings are varied. Cutting materials precisely from a digital rendering and—in the case of the Othello modular design—eliminating the need for vertical sheer walls meant even less material waste. And because this form of construction often requires smaller crews onsite, less transportation of materials and a shorter project schedule, the overall demand for resources can be optimized and reduced.
Prefabrication can also play a role in cutting carbon emissions. Morefield points out that in a study by the University of Alberta, a modular project showed a dramatic decrease in carbon emissions when compared to an identical site-built project. “The factory-built project had a 43-percent reduction in carbon emissions. It was exactly the same building—same envelope, same material, everything. From a transportation aspect alone, from a reduction of construction time [and travel distance of labor and materials] alone, it was a 43-percent reduction.”
Cost Savings and Efficiencies
Along with cutting waste and reducing carbon emissions, prefabricated architecture has been shown to cut costs and boost efficiencies across all aspects of construction. By working smarter rather than harder, prefabricated architecture produces less material and fuel waste and decreases the amount of time that can be lost in the construction process due to weather or other unforeseen events.
As dependence on accurate metrics continues in the architecture and building industries, prefabricated lumber buildings will only increase as well—a trend all three experts have already seen exploding across North America. The building industry is now embracing digital tools such as 3D modeling, building information modeling (BIM) and computer numeric control (CNC) machines, making prefabrication amongst building professionals easier.
And as Ryan Smith, author of Prefab Architecture: A Guide to Modular Design and Construction recently observed, “the capacity of prefab to deliver buildings that respond to time, change and reuse/recycle may be its greatest benefit toward total lifecycle sustainability in the future.”
To learn more about how you can use wood for your next prefabricated project, contact Think Wood.