Why Mass Timber Makes Sense – and Saves Dollars
HKS is a firm committed to exploring new building methods and materials, community health, design excellence and sustainability. That’s why we are a major proponent of the advantages of mass timber construction. Even though mass timber buildings represent only a fraction — less than .000189 percent — of the country’s commercial buildings, there are many reasons why this building type is a smart choice.
While some claim mass timber can be as much as 5 percent less expensive than steel and concrete construction, additional cost savings are possible through shorter construction time of prefabricated panels, less labor required for installation and in lower foundation costs due to less structural weight than in the material itself, which can cost as much or slightly more than concrete per square foot.
Mass timber also sequesters CO2 and its manufacture is far less carbon intensive than either concrete or steel. In addition, mass timber has a high strength-to-weight ratio that allows it to perform well during seismic activity, and its fire resistance properties meet or exceed most code requirements.
Mass Timber Buildings Have Health Benefits
There are also considerable health and aesthetic benefits of mass timber construction.
Research shows a link between exposed wood structural elements and greater workplace satisfaction and productivity. Studies also point to a growing body of evidence that natural materials, plants, natural light and access to nature relieve stress, the underlying cause of many forms of physical and mental illness. Variations in color and texture of wood and its tactile qualities can be both healthful and beautiful.
Health facilities have been wary of mass timber due to the need for infection control. Because mass timber is engineered, its surface is smooth, free from cracks and knots seen in raw wood. It can also be coated creating a surface that can withstand industrial cleaning agents. Unlike other building materials, it also has reduced off-gassing, which translates into better air quality.
HKS Principal Kirk Teske notes the advantages of bundling underfloor air distribution (UFAD) with mass timber.
“Because UFAD doesn’t mix the air in the occupied zones like traditional forced air systems, it’s healthier,” Teske said. “UFAD also allows you to keep the HVAC ducts, electrical conduits, and data cables under the floor leaving the wood structure exposed. Done correctly, you feature the biophilic aspects of the wood structure with only the sprinkler piping and lighting systems remaining as a part of the ceiling structure.”
Considering the post-pandemic state of the commercial office market, Teske believes this combination would provide that sector with a unique niche offering that is especially attractive to corporate users that value environmental sustainability and healthy alternatives for their employees.
The Flexibility of Wood
Our practice spans a multitude of building types from senior living to commercial mixed use, education to hospitality, health to sports and more. Regardless of the building type, our clients are interested in creating spaces that are highly functional, adaptable, affordable and celebrated by users and the community-at-large.
Mass timber products, which come in a variety of sizes and forms, can help fill the bill. Cross Laminated Timber (CLT), is a wood panel system that uses wood stacked crosswise at a 90-degree angle and glued into place. Its strength, dimensional stability and rigidity make it suitable for use in mid-and high-rise construction. Nail-Laminated Timber (NLT), is dimensional lumber placed on edge with individual laminations fastened with nails or screws.
Dowel-Laminated Timber (DLT), panels are stacked like NLT and friction-fit together with hardwood dowels. Its strength comes from friction of the dowels, so it doesn’t use adhesives, nails or screws making it more sustainable, easier to mill and attractive for exposed structures. Glued-Laminated Timber (Glulam), is a structural engineered wood product commonly used for beams and columns. It allows for long spans of exposed framing as well as curvature.
So, Why Aren’t There More Mass Timber Buildings?
While hailing the energy-saving features of mass timber, some skeptics have expressed concern for deforestation due to wood’s increasing popularity.
“Most of the wood used in mass timber comes from trees that can be sustainably managed through responsible forestry practices,” explained Teske. “With smart design and planning and collaboration with knowledgeable manufacturers and contractors, we can mitigate any possible downside to using wood. A 2014 study stated that using wood as a building-material substitute could save 14%-31% of global CO2 emissions and 12%-19% of global fossil fuel consumption. The positives greatly outweigh any negatives.”
Another reason cited for not using mass timber is that it is not as cost effective as its purported to be. According to Ryan Ganey, HKS Structural Engineer who has worked on several mass timber buildings in the states of Washington and Texas, selecting consultants with experience in mass timber construction can help alleviate cost concerns.
“It’s important to work with a contractor who has had some experience in mass timber to recognize the full benefits,” Ganey said. “Some contractors price mass timber higher because they have not had as much experience with it and they want to cover themselves. But as it becomes more popular, contractors better understand the cost of materials and labor and can price more accurately.”
Another possible reason for not using timber is building codes. But in 2019, the International Code Council (ICC) approved a set of proposals that would allow tall wood buildings as part of the 2021 International Building Code (IBC). If design meets these code requirements, buildings can be built up to 18 stories.
But what about fire safety?
In a fire, heavy timber chars on the outside while retaining strength. That slows combustion and allows occupants to evacuate the building. According to David Barber of Arup, in recent fire testing, a seven-inch wall of CLT lasted three hours and six minutes — one hour longer than code requirements.
A few years ago, the only mass timber manufacturers were in Canada or Europe. Today there are about a dozen scattered across the United States making sourcing easier and further reducing the carbon footprint of the material by eliminating importing and shipping. In addition, mass timber can be beautiful and might make a significant difference in the speed of leasing or sales of commercial, mixed-use and residential space.
As of December 2020, 1,060 commercial mass timber projects had been constructed or were in the design phase across the U.S., according to Woodworks — Wood Products Council. Developers, investors and corporations are embracing the idea that mass timber may give them an edge in the leasing or sale of real estate and in recruiting and retaining top talent. We can’t wait to help them achieve their goals.