What are prefabricated wood building systems?
Any building that contains significant sections built off-site, in a factory, and then assembled on site, is taking advantage of prefabricated construction. In some cases, distinct portions of a structure may be prefabricated and in other cases nearly all the components may be factory-built. Wood’s versatility, lighter weight, and ease to work with make it well-suited to prefabricated construction methods. Such buildings are generally constructed using one of two approaches—as a kit-of-parts or as an assembly of finished modules.
Prefabrication facility | Photo credit: Metric Modular
Wood prefabrication as a kit-of-parts
Prefabricated wood building kits are made up of prefabricated components delivered and assembled on site, much like life-sized Lego. This is most often achieved using prefabricated panels that can form entire sections of a building such as roofing components or structure (ceiling, decking and beams), building structure (wall panels, beams, columns and shear panelling) and even glazing packages (walls with built in windows and entrances). Panels can be open—a preassembled wall that is later fitted with insulation, weather barriers and cladding—or closed, such as a total preassembled wall panel complete with windows, doors, plumbing, electrical and finishes.
Brock Commons Tallwood House | Photo credit: KK Law
How to realize the full benefits of prefabricated wood construction
Factory-built construction could reduce the time to complete a construction project by up to 50 per cent and cut costs by 20 per cent or more, according to several studies. And prefabricated technologies—using both light-frame and mass timber—are offering a nimbler, quicker and more integrated way to construct today’s buildings. Sophisticated 3D modelling and digital software give design teams the ability to simulate the assembly of a building from concept and design to excavation and construction, meticulously planning each phase to completion. But how do teams take full advantage of these opportunities? In this report, you’ll learn what you can do to expand the use of prefabricated wood building systems in your next project.
Wood prefabrication as modular construction
Finished modular construction is factory-built three-dimensional modules, shipped to the site complete with plumbing, electrical, paint, flooring fixtures, cabinets and appliances. This turn-key approach means units can be craned into place with little onsite assembly required. Once the modules are in place licensed building professionals (electrical, plumbing, mechanical and structural) complete the work.
This form of construction is growing in popularity and is particularly well suited to buildings such as student residence, hotels, staff accommodation and in instances when site access is limited or in remote regions.
Kelowna hotel | Photo credit: Metric Modular
Building systems used in prefabricated wood construction
Prefabricated wood systems are made from either conventional light-frame construction or mass timber systems, and finished construction often involves a mix of both.
Light-frame
Conventional light-frame wood construction—when dimension lumber and materials are delivered to site and then cut and installed according to a prescribed blueprint—still makes up the bulk of construction. Typical light-frame construction is built of repetitive wood framing to form rafters or trusses using standard dimension lumber. Oriented strand board (OSB) and plywood form roof decking, floors and walls. This same construction can be completed in a controlled environment, built as nearly completed modules—with plumbing and finishes—that can then be delivered to site for installation.
Mass timber
Mass timber products are thick, compressed layers of wood that serve as the load-bearing structure of a building. Because these products are lighter than other construction materials, they lend themselves well for prefabricated wood building systems allowing a speedier and more efficient process. Cross-laminated timber (CLT) is a popular mass-timber product because of its versatility. CLT is used to build floors, walls, elevator shafts and roofs. Glue-laminated timber (glulam) is often used as headers, beams, columns, trusses or in load-bearing arches. There are several other engineered wood products used in prefabrication, including nail-laminated timber (NLT), dowel-laminated timber (DLT), laminated strand lumber (LSL), laminated veneer lumber (LVL), and parallel strand lumber (PSL).
BC Passive House Factory | Photo credit: Ema Peter Photography
How prefabricated wood construction can make housing more flexible and versatile
Prefabricated wood modules can be assembled and disassembled, modified or relocated making it well-suited to the rising demand for flexible housing, a trend that is giving residents the ability to change the size and composition of a home over time, boosting affordability and value. Modular wood construction is an ideal material for flexible systems such as interior walls that can easily be reconfigured to expand or shrink the size of a dwelling depending on the occupants’ needs. Smaller units could be combined when a family has children, or a three-bedroom unit could be split up when a child leaves for college.
Abbotsford Supportive Housing | Photo credit: Metric Modular
Factory-built wood buildings deliver value and cost-savings
Trinity Western University in Langley, saved time and money when they assembled a student housing building with 90 wood-built modules. Jacobson Hall was built in just nine months adding beds for another 220 students. Each dorm room takes 14 days to complete, a process the fabricator says is approximately 50 per cent faster than conventional construction.
Photo credit: Metric Modular
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The Confluence | Photo credit: Matthew Bolt Photography
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