CLT: A new building method makes gains in the Northwest

            If it’s natural, sustainable and has a small carbon footprint could a more than 20-year-old building system that began in Europe find a dedicated following in environmentally-conscious Oregon?

            The future of cross laminated timber, or CLT, as a structural component to mostly replace concrete, drywall and other materials will be tested with product from a southern Oregon mill and several projects underway in the state.

            By some estimates CLT could be poised to become a $4 billion national market in the foreseeable future.

            CLT technology relies on the additional structural strength derived from gluing an odd number of solid-sawn wood layers, three to nine for example, perpendicular to each other. Industrial presses then compress the layers into straight panels up to 12 x 60 feet and 20 inches thick depending on the manufacturing facility. In building construction CLT is used for roofs, walls and floors. 

CLT simplified

A Canadian developer is using primarily black spruce from boreal forests but CLT can combine spruce, fir, pine, cedar and other wood, including timber salvaged from wildland fires.

In Europe and Canada “tall timber” CLT structures, some more than 20 stories, are in the planning stages or under construction.

Among advantages of CLT most often cited are:

·        Use of a renewable resource with less environmental impact on climate change and pollution

·        Solid wood panels have the strength of concrete, but are five times lighter, and are 15 times lighter than steel

·        Thermal insulation is seven times greater than concrete and 500 times more than steel.

·        Fire resistance is greater than sheet rock

·        Construction can be faster with pre-fabricated panels and fewer tools required

·        Wood creates healthier interior conditions as the result of reduced toxic emissions compared to other materials

A leading CLT proponent is Vancouver architect Michael Green. With crusading zeal Green has carried the CLT banner to Ted talks and seminars, and is the designer force behind the Wood Innovation and Design Centre in Prince George, BC.

            The 6-story plus mezzanine and penthouse building, in cooperation with the University of Northern British Columbia, is a demonstration of CLT construction. It’s funded by more than $25 million from the provincial government and intended to be a linchpin of downtown revival in the largely resource-dependent city of north central BC.

BC's Wood Innovation and Design Centre

            In a 2013 Ted Talk, Green made the case for wood over conventional concrete and cement construction in an example of a 20-story building. http://goo.gl/DhP2aq

            “If we built a 20-story building out of cement and concrete, just manufacturing that cement would produce 1,200 tons of carbon dioxide. If we built it with wood, we’d sequester about 3,100 tons, for a net difference of 4,300 tons between the two scenarios. That’s the equivalent of about 900 cars removed from the road in one year,” Green said.

            The potential of  CLT was credited by Valerie Johnson, heir to the founder and now chief executive of D.R. Johnson Lumber Co. in Riddle, OR, with convincing her to guide the company toward CLT production after she heard a presentation by Green in 2010. The Johnson mill had been hard hit by the recession and needed an economic lift as did the timber industry dependent town in souteastern Oregon.

            In a published interview, Johnson said she an another executive decided to visit CLT manufacturing  facilities and projects in Austria and Germany. Following the tour and with existing capital and other funds including a $50,000 Oregon Best grant they added the necessary equipment at the company’s laminating production line.

In September of this year, Gov. Kate Brown announced that D. R. Johnson had become the first company in the country to be certified for manufacture of CLT for structural use.

With the APA/ANSI certification, by the American Plywood Association/American National Standards Association guidelines, the company currently produces CLT panel is sizes up to 10 x 24-feet in three, five and seven layers, primarily using either Douglas fir or Alaskan yellow cedar.

The company will also receive a $100,000 grant from Business Oregon, the state economic development agency, to offset costs of the CLT production line.

 CLT as a structural building technology had its genesis in Austria in the 1990s and there are many “tall-timber” buildings--residential and commercial--throughout Europe.

 What would be one of the world’s largest “wooden skyscrapers,’’ known as the HoHo is planned for Vienna, at more than 270 feet with a hotel, apartments, restaurant, a wellness center and offices. In Paris a 35-story CLT based apartment tower in the planning stages.

In Montreal, the Arbora mixed project in the city’s Innovation District will employ CLT material in three 8-story buildings totaling 597,000 square feet that will include 430 condo, townhouse and rental units and main floor commercial space.  Arobora will use black spruce from the northern forests of Quebec.

Arbora-Montreal's CLT mixed use community

            Manufacturing of cross laminated timber first migrated across the Atlantic to Canada in the early 2000s, buoyed by that country’s ample forest resources and receptive industry and government support.

            In 2012 the largest CLT facility in the United States began production in Columbia Falls, MT, about 10 miles from Whitefish and 15 miles to the West Glacier entrance to Glacier National Park.

            The Montana company, SmartLam, has a much larger plant than Oregon’s new CLT company. But as of early November. it had yet to receive certification for manufacturing structural CLT. The company has primarily provided  platforms at oil drilling locations, for heavy machinery support in wet soil areas of the southeast, and for bridges and other industrial uses.

            Mike Rossi, VP of Finance and Business Operations at SmartLam, said in a recent visit to the Montana plant in early November that the company is eyeing Oregon as a CLT market “far ahead” of other states in embracing the technology.

            SmartLam is gearing up for substantially increased production when it expands from it’s current 40,000 square foot facility to a new 160,000 square foot plant capable of processing 4 million board feet or 160 truckloads in a single month.

Until the D. R. Johnson mill in Oregon gained certification a Penticton, BC company, Structurlam, and Nordic Structures of Montreal, produced most certified structural timber in North America. In 2009 the BC government approved construction of six-story residential wood buildings, jump starting adoption of CLT with more than 50 Canadian projects and dozens more in the planning stage over the past few  years.

            A 2015 revision in the International Building Code has further opened doors for CLT construction in North America.

            Apart from the building code obstacles, which the IBC revision addresses on a large scale, early skeptics of CLT have questioned potential additional cost, fire resistance, the impact of timber harvests on the environment and the need for specialized building crews.

            In response, those promoting CLT note that costs are competitive with conventional construction and can even be lower with reduced foundation expense due to lighter loads, and faster construction times.

How CLT works-New York Times 2012

A 2014 study of alternative construction in the Northwest by Mahlum Architects and Walsh Construction, with Seattle and Portland offices, and Seattle engineering firm Coughlin Porter Lundeen concluded that CLT construction in a 10-story residential building could be 4% less expensive than conventional building methods. And  more savings could be realized by mixing wood frame and CLT, the study added.

            Some CLT advocates also maintain crews can be easily trained and that working with CLT panels is similar to traditional “glu-lam” construction.

            As for fire resistance, they cite the example of trying to start a campfire with large diameter logs. CLT mass timber acts more like concrete, they note, and when ignited tends to burn itself out.

            Regarding the harvest impact, statistics show that in the past 50 years the North American annual timber harvest rate was 2%, compared with an annual tree growth rate of 3%. Moreover CLT has the potential to make use of trees felled by beetle kills, which results in increased release of carbon during decay.

            In Oregon one demonstration of CLT’s future will be a 12-story mixed use building, to be known as Framework,  in Portland’s Pearl District. It will include ground floor retail, five floors each of work space and living areas and a rooftop “amenity” area.

Lever Architecture's CLT design for Portland

            The Oregon CLT movement gained momentum in January  of 2015 at the Oregon Leadership Summit with about 1,000 attendees and Michael Green was among the speakers.

            Not everyone in the design-build community believes CLT will emerge quickly in Bend.

An Bend-based architect who has offices in Bend and Whitefish, MT--only a 10 minute drive to the large CLT manufacturing facility in Columbia Falls-- points out that given CLT relies in part on timber harvest its claim to “green” is not completely assured.

            He questions whether the Bend building community will easily adopt CLT design and construction. Contractors and their subs are very busy in the currently active market and will not likely embrace something untried locally, he observes.

            Washington state appears to lag Oregon in design and building codes that open the way for CLT.

            In  mid-October CLT was the centerpiece of the Building for a Sustainable Future conference in Seattle that brought together an impressive list of 80 leaders in government, the design and building industry, business, tribes and the environmental community.

            Sponsored by Forterra, which began several decades ago as the Seattle-King County Land Trust, the conference identified outdated building codes, including those related to seismic and fire issues, and limitation of CLT  construction to six stories as obstacles to address.

8-story CLT apartment building in Finland

            Also noted was the extra time and costs for research, testing and demonstration to satisfy agencies involved in adopting and enforcing new building codes.

            “For Washington to grow a market for CLT/mass timber, incentives are needed to level the field with conventional building materials. Key demand points: building codes, education, incentives, public/government support.” concluded the Forterra post-seminar overview.

            Nevertheless, CLT has gained a toehold with smaller residential and commercial projects in Seattle with one of the more well-known efforts by Cascade Built. The company has finished several smaller CLT  homes in the city’s Madison Valley.

A CLT residence in Seattle

            In a June 2015 online article Cascade Built president Sloan Ritchie described his company’s work on a 1,500 square foot home for Seattle architect Susan Jones.

            The company built the home with panels manufactured by Structurlam of Penticton, BC in a combination of spruce, pine, balsam fir for the exterior and blue-beetle-kill lodgepole pine in some interior applications. Altogether construction required 67 panels in sizes of 2 x 10 feet to 8 x 35 feet and weighing 200 to 2,800 pounds.

            In assessing the experience, Ritchie explained that, “The overall lesson here is that the builder who has the opportunity to use CLTs needs to systematically think through everything. Given enough upfront planning, it’s a great system that creates a high-quality result.”