Cross-laminated timber is a hot topic in the A/E/C industries. Its strength could make wooden skyscrapers a reality. Its simplicity makes for incredibly quick construction. It could provide a use for otherwise unusable wood, including 60 million acres of forests that have suffered from pine beetle infestation. It could breathe new economic life into rural communities that have suffered from declines in the timber industry. And it could provide a more environmentally friendly alternative to carbon-intensive building materials like concrete and steel.
DCI Engineers has always been at the forefront of industry trends and new building technologies – look no further than our collaborations with CollinsWoerman on the Sustainable Living Innovations standard or many examples of successful modular construction projects. To that end, we had a big presence at the Mass Timber Conference presented by Forest Business Network and WoodWorks March 22-24 in Portland, Oregon. Dean Lewis, from DCI’s San Francisco office, and Greg Mercurio and Adam Jongeward, from our Portland office, were all on hand.
Here’s what Lewis, a project manager in San Francisco, took away from his time at the conference:
- “CLT is getting all the headlines, but there’s more to mass timber than just CLT. ‘Mass timber’ refers to a wide variety of composite wood materials, some of which we already widely use in our projects. Laminated Strand Lumber, Laminated Veneer Lumber, Nail Laminated Timber, Dowel Laminated Timber and Tongue and Groove Decking all provide some of the same benefits as CLT, though each comes with their own sets of plusses and minuses as far as cost, constructability and efficiencies.”
- “Mass Timber projects don’t have to be made entirely of wood. Lots of our projects meld wood, concrete, steel and other construction materials, utilizing the advantages of each material. It was really cool to see a DCI project – the Bullitt Center – used as an example in a presentation of a ‘Mass Timber’ building even though it had steel-braced frames and a concrete core.”
- “People are starting to recognize how much better wood construction can be for the environment. The US Green Building Council recently announced that using responsible, legal sourcing of wood could garner projects credit towards LEED certification. The industry is putting more and more thought into what building materials we use and the environmental impact of their production.”
- “CLT and other mass timber products still have to overcome some skepticism from building officials, who are concerned about fire ratings, moisture build-up and sound ratings. Right now, most jurisdictions require that a CLT or mass timber project use alternate means and methods compared to conventional building code standards. With projects and offices across the country, DCI has a long history of working with different jurisdictions and using alternate means and methods to design our projects. But this is all changing quickly as we start seeing more examples of successful CLT projects – in 2015, CLT was added to the International Building Code and Portland recently approved plans for Carbon12, an eight-story CLT mixed-use building.
- “This is still a developing technology, and the supply chain is not as established as it is for heavy timber, much less concrete or steel. Many of our cost studies on CLT and mass timber are old or obsolete, and developers and architects are eager to get a better handle on the costs and production time. With the increasing popularity of CLT, there are now production facilities in Oregon, Montana and British Columbia, so cost and delivery schedules should start to become clearer in the near future. In Europe, where CLT is more widely used, it’s roughly the same price per cubic meter as glulam. America isn’t there yet but there’s no reason to believe we couldn’t get there.”
- “A collaborative approach is key for mass timber projects. In many wood projects, the structure IS the architecture and there is no telling where the architecture ends and the structure begins. Mechanical needs to strategically place their utilities in order not to block the ceiling with large ducts; structural needs to provide sleek connections to show off the timber; and the architect needs to develop cladding and finishes that enable the structural members to be shown off. One of DCI’s strengths is the way we collaborate with architects, owners and sub-contractors throughout the design and construction process.”
About the Author
Dean Lewis is a project manager in DCI’s San Francisco office. He’s been privileged to work on a wide array of projects with large and small scales, from private to public, schools, residential, commercial, hospitals, industrial, and transportation. His combination of technical design, project estimation, construction cost, and customer service experience has made him a key part of the DCI team.