Cross-Laminated Timber Could Be The Next Big Thing In Construction
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Rising labor and material costs have many developers and contractors looking to new ways to build their projects. One emerging material is cross-laminated timber or mass timber, which is a prefabricated wood system that creates a dense wood panel. It requires less labor and helps decrease construction costs.
While it has been used in Europe for two decades, it has become a popular material in the Pacific Northwest after timber died off due to disease. After the timber industry became depressed, the government wanted to find ways to use the timber and began funding research on CLT and mass timber on high-rise construction, according to KPFF Managing Principal Marc Press.
“What started in the Pacific Northwest is fighting its way to the rest of the country,” Press said during a recent Bisnow event in San Francisco.
Lendlease first started to use CLT in Australia, the company's original base. Lendlease has since used CLT on multiple products and is using it to develop a 100-unit hotel outside of a military base in Alabama, according to Lendlease Senior Vice President Bruce Berardi. Lendlease has used it to build offices, multifamily and public buildings.
CLT was used for Oregon State University’s student center, an office project in North Portland called Albina Yard and other projects throughout Portland, according to Press. It also is being used to build a train station in Tacoma, Washington.
Berardi said CLT requires half of the on-site labor needed and saves 30% of time on the construction schedule.
Do The Benefits Outweigh The Challenges?
CLT offers benefits over other materials beyond just its quicker project delivery. It performs better seismically than typical wood buildings, which have undergone criticism lately after a spate of fires at under-construction projects. CLT stands up better than steel buildings during a fire, according to Press.
“The thermal and acoustical performance is superior to stick-frame,” Berardi said.
The floor assembly also is thinner than wood-frame and can be as thin as six inches and as thick as 8.5 inches, which can add up to six inches of floor height on each floor, according to Berardi.
CLT can be left exposed and does not need gypsum board over it. CLT also allows for prefabrication, and Lendlease has used it to create prefabricated stairs and bathroom pods that can be dropped into a building, Berardi said.
While CLT is faster to build with than metal stud and concrete, it is heavier than regular wood and requires the right soil conditions and geometry to maintain its seismic resilience, Berardi said.
The biggest challenge to more common use of CLT, especially in the Bay Area, is the slow permitting process. Since it is a new material, each building department needs proof that the material will stand up for a long time, Press said.
Press said he anticipates CLT will become a part of the building code system by 2021 so it will be much easier and more cost effective to use it. It currently requires a special permit process.