7 reasons for wood's popularity in midrise housing
Engineered wood is arguably the fastest-growing structural product solution for midrise multifamily buildings. Most U.S. raised wood floors are now made with I-joists, priming the use of laminated veneer lumber (LVL), according to industry data.
New all-wood, podium-style residential structures are popping up from California to Virginia, too, using wood structural panels, glulam and LVL beams, and open-web wood trusses, reports Architectural Record. Wood shear walls and structural insulated panels (SIPs) add new resistance against seismic shear and wind uplift forces in buildings from three to seven stories and taller.
Yet the reasons for the surge of wood innovation go beyond the physical properties of products. Here are seven of the most important:
1. Green building and wellness. Think of the multipronged benefits of wood for green building and occupant health. A seminal study by Oregon State University concluded that wood “uses less overall energy than other products, causes fewer air and water impacts, and does a better job of the carbon ‘sequestration’” to help address global climate challenges. A decade later, engineered wood is central to environmental design, nowhere more prominently than in mixed-use housing.
2. Practical innovation. Driven by midrise market needs and architectural innovation, construction methods using glued engineered wood have translated from ambitious R&D programs to widespread best practices in just a few short years. Cross-laminated timber (CLT) panels have come of age, with a widely cited standard and a mini-explosion of residential and commercial uses. Glulam’s reputation and strength outstrip those for steel, pound for pound, offering bigger spans and greater stiffness than comparable sections of dimensional lumber.
3. Midrise multifamily markets. Consider the kinds of projects driving urban and suburban residential developments today. The first floor often has commercial and retail uses, plus the housing units often compete on such features as ceiling height and finish quality. In response, architects have embraced all-wood podium solutions that allow for higher ceilings and increased interior clear heights, with attractive interior finishes of exposed structural members, architect Blake Jackson said. Approaches include gypsum-concrete-topped wood structural panels on I-joists and glulam beams, as well as open-web wood trusses and LVL beams below plywood and OSB floor sheathing.
4. Life benefits. There’s more for real estate agents to boast about regarding their all-wood condominiums and apartments. Housing has traditionally relied on wood, and for good reasons: It has inherently excellent acoustics, so homes are more serene. Wood offers good thermal resistance, further improving homeowner comfort. Plus, engineered wood meets or exceeds every fire safety code, too, for peace of mind.
5. Cost effectiveness. Developers like it, too. Whether on material first costs and construction scheduling or for its life-cycle cost advantages, all-wood structures are highly competitive for typical midrise multifamily projects. Compared to the hybrids of wood frame atop a concrete base, the all-wood podium cuts both project costs and total construction time, say architects like Michael Malinowski, who has used the techniques in the Sacramento region.
6. Seismic codes. For seismically active zones like California, many engineers advocate all-wood podiums. The structural frames are less massive, reducing lateral design loads, according to Designing for Earthquakes. Engineered wood can allow for faster-built, more economical and sustainable seismic solutions as compared to common concrete podiums.
7. Embodiedenergy and life-cycle energy use. A nonprofit alliance of 15 research universities confirmed findings dating as early as 1976 (by the National Academy of Science) with a seminal analysis of wood’s energy benefits over steel and concrete. For a residential project in Minneapolis, steel framing demands 17 percent more energy than wood, with a 26 percent higher global warming potential (GWP). In Atlanta, the group concluded that equivalent housing projects of concrete require 16 percent more energy and yield a 31 percent higher GWP.
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