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.
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| 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.
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| 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.
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| 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.
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| 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.
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| 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.
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| 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.
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| 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.”
