Mass Timber is Changing Real Estate
Panel construction at a mass timber warehouse in Dallas, Texas by USAA Real Estate and Seefried Industrial Properties. Photographer: Erika Brown Edwards / courtesy Timberlab.
What is mass timber?
Mass timber is a broad term that encompasses various types of panelized and engineered wood products including columns, beams, and panels. Designed as an alternative to carbon-intensive building materials like concrete and steel, it has comparable strength and a lighter weight.
Mass timber provides both aesthetic appeal as well as the potential to contribute to the decarbonization of buildings.
What’s driving mass timber adoption?
Progressive building codes
New mass timber products
Innovative building systems
More designers and builders with expertise
Increasingly affordable products and systems
Interest in sustainability-driven building materials and designs
With the wide range of mass timber uses and applications, as well as the increased availability of new building materials on the market, wood is a preferred option for low-carbon, “green” construction.
Image: StructureCraft’s plant pre-fabricating custom board panels to be used at Hotel Magdalena’s exterior walkways in Austin, Texas.
Types of engineered wood:
Cross-Laminated Timber (CLT)
The most common type of mass timber for structural applications in construction is cross-laminated timber (CLT) – which is manufactured by stacking trimmed and kiln-dried boards of wood in layers with the grain in perpendicular orientations, glued together with strong adhesive.
CLT is well-suited for replacing concrete in walls, roofs, ceilings and floors.
Glue-Laminated Timber (Glulam)
Glue-laminated timber is made with parallel layers of kiln-dried, stress-tested wood bonded together with durable structural adhesives. The wood panels are positioned based on their stress results to ensure that the resulting beam can absorb stress proportionally. The panels are laminated using a hydraulic press and can be formed into members of different shapes including curves and arches.
Glulam is typically used for load-bearing elements like columns and beams.
Laminated Veneer Lumber (LVL)
Wood veneers are bonded under heat and pressure into large blocks called billets. Applications include beams, trusses, planks, and rafters.
Nail-Laminated Timber (NLT)
Lumber is stacked on edge and fastened with nails or screws. Applications include floors, ceilings, decking, roofing, and elevator shafts.
Dowel-Laminated Timber (DLT)
Similar to NLT, but instead of nails the panels are friction-fit with hardwood dowels. Applications include horizontal spans, flooring, and roofing.
Benefits of mass timber
Reduced carbon footprint.
A 2019 University of Washington study conducted a life cycle analyses of two similar buildings, comparing a hybrid CLT commercial building to a reinforced concrete building. It was found that the hybrid CLT building had a 26.5% reduction in Global Warming Potential.
Why? Because timber acts as a “carbon sink”, preserving carbon that is stored in the wood, preventing its release back into the atmosphere as carbon dioxide.
With sustainable forest management and manufacturing, timber can capture and store carbon for a building’s full lifetime.
Photograph showing a wood beam supporting twisted steel beams.
Prefabrication allows for quicker construction and minimizes material waste.
Engineered wood can be prefabricated to exact specifications in a factory, as opposed to cutting and assembly on-site.
This not only speeds up the construction process, but also reduces material waste because space for MEP, windows, and doors can be included in the manufacturing process.
Earthquake and fire resilient.
Timber is strong, lightweight, and highly ductile which makes it an attractive material choice in high-seismic regions. When concrete cracks due to seismic events, buildings typically require demolition and reconstruction. In contrast, wood-frame buildings can be designed to avoid damage to the primary structure and are thus more easily repaired.
Engineered wood is also very fire-resistant. In the event of a fire, the outer layers of the timber char at a predictable rate. The char layer acts as protective insulation to slow down combustion and the inside layers can retain their strength. Materials like steel are less predictable under combustion once they reach yielding temperature.
Source: Naturally Wood
Ascent, the world’s tallest mass timber building
The Ascent in Milwaukee, Wisconsin, is officially the tallest mass timber building in the world at 25 stories high.
The USDA Forest Service provided support for Ascent through the agency’s Wood Innovations program and Forest Products Laboratory fire testing. A wood innovations grant helped with engineering and design work, and the lab conducted critical fire testing of glued-laminated timber columns (glulam).
The burn test proved that oversized, yet unprotected, glulam columns do not lose structural integrity since outer layer charring protects internal layers. In fact, the lab’s glulam columns performed so well, they qualified for a three-hour fire resistance rating. Source: usda.gov
Aesthetics
Mass timber also makes for stunning wood interiors. Not only do the biophilic properties of exposed wood make spaces pleasant, building with timber creates an opportunity to use the structural materials as the finishes, reducing the total amount of material needed.
200K SF mixed-use campus in Marina Del Rey, CA
The two-story project uses mass timber, cross-laminated timber (CLT) and hybrid (wood with steel or concrete.) Project Team: Lincoln Property Group (developer); Holmes and Megan Stringer (structural engineers); Rios Clementi Hale Studios (architect); Eric McDonnell (mass timber technical lead).
“Steel and concrete will always have their place,
but we have much to gain by increasing the use of mass timber in our built environment. It’s green. It’s beautiful. It’s fast. And it’s safe.
While there are legitimate differences of opinion about the finer details of carbon accounting and life cycle analyses, any honest sustainability debate must acknowledge that we are better off using timber, a carbon-sequestering and renewable material, than materials which rely on permanent extraction and massive amounts of energy in production.
We owe much to those in the forestry industry who are committed to maintaining the health and stock of our forestlands; without sustainable forestry practices, the case for mass timber would be just another gimmick.”
– Tanya Luthi, PE, Vice President, Entuitive; Board of Directors, WoodWorks (source: Think Wood: Mass Timber Design Manual Volume 2)
Image: 1 De Haro, San Francisco, CA | Perkins&Will | Photographer: David Wakely
The future of mass timber?
Mass timber is a relatively new material, and research and testing are still in early stages. Timber buildings have become increasingly popular, especially in Canada and Europe over the past few decades, and building codes have responded to allow for more advanced wood structures.
As of 2021, provisions for up to 18 stories of Type IV-A construction have been accepted into the International Building Code (IBC).
Interactive Mass Timber Maps
Explore mass timber projects in the U.S and Canada.
This map of mass timber projects in Canada also features data on 20 solid wood manufacturing facilities across Canada, demonstrating the growing capacity of domestic producers.
