Product problems at OSU project highlight CLT growing pains
As
“mass timber” methods for building taller wood structures gain momentum the
concrete industry is mounting opposition to proposed new international building
codes on the eve of an important upcoming vote by a construction industry
standards organization.
The
primary issues against code changes, as argued by concrete industry groups, are
fire safety and structural strength related to buildings constructed with cross laminated timber, or CLT.
Recent
setbacks involving construction of the new Oregon State University’s Peavy Hall
at the forestry school, and cancelled plans for a 12 story Portland building,
have raised questions about whether the rapid ascent of CLT adoption should get
a closer look.
The
concrete lobby also maintains that the environmental advantages often cited for mass timber over
conventional concrete buildings are reduced over the life of a building when
considering energy costs for heating, ventilation and air conditioning.
CLT is the method of gluing solid wood boards in
perpendicular layers which are then compressed by high compression hydraulic equipment to
form strong construction panels. CLT panels are typically two to 10 feet wide
with typical configurations up to 60 feet and 20-inches thick.
The
method is different from conventional glulam, also considered in the mass
timber category, but without the wood layers cross-positioned 90-degrees. Glulam is more often used for interior exposed posts and beams.
While
the IBC and individual states, including Oregon, are moving ahead to allow much
taller buildings using CLT, besides the concrete industry there’s been pushback
from various fire safety groups including firefighter unions and the
International Association of Fire Chiefs.
Their primary objections focus on the difficulty of suppressing blazes in buldings that could
reach 18 stories in some building types under the new IBC changes. The Oregon
Building Codes Division in August essentially reflected the proposed IBC changes when
it revised the state building code to allow tall wood construction up to 18
stories and 270 feet, depending on whether a structure is sprinklered and the type of occupancy.
In
March of 2018 a 1,000 pound section of a CLT floor at OSU’s Peavy Hall
collapsed and subsequent tests indicated that as many as 80 panels had gluing
defects, the Oregonian reported. The panels were manufactured by Riddle, OR
based DR Johnson, a legacy timber mill that had begun production of CLT a few
years ago with substantial support of state sponsored grants and various public
officials intent on boosting the state’s depressed timber industry.
The Peavy Hall Forestry School project is viewed as an important showcase of Oregon's effort to be a leader in CLT construction and call attention to new products for the timber industry. Bid criteria stipulated that the project's CLT producer had to within 300 miles of OSU, effectively eliminating the possibility of a producer from outside the state.
The Peavy Hall Forestry School project is viewed as an important showcase of Oregon's effort to be a leader in CLT construction and call attention to new products for the timber industry. Bid criteria stipulated that the project's CLT producer had to within 300 miles of OSU, effectively eliminating the possibility of a producer from outside the state.
In
September Engineering News Record-Northwest reported an investigation team
including independent engineers concluded problems had resulted when
panels were preheated in a cold temperature mill before application of glue, which subsequently
impeded bonding as the glue dried prematurely in the compression process.
Construction
resumed after several months delay for the investigation, and for DR Johnson to restart the production process in a temperature controlled environment. By some estimates
the 80,000 square foot bulding, intitially budgeted at $60 million, is on track
to cost $79 million.
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| A CLT press like the one at DR Johnson |
Whether
due to concern over the Peavy Hall problems or financial considerations,
developers of the proposed Framework 12-story building in Portland that would have used
CLT announced they would not proceed.
Ironically,
DR Johnson was the first producer in the United States to receive certification
from the American National Standards Institute to provide CLT for structural
uses in buildings. However, SmartLam of Columbia Falls, MT, less than 20 miles
from the southernmost entrance to Glacier National Park, was the first US
producer of CLT and has a much longer record of supplying products for
industrial uses such as job site matting and bridges.
SmartLam received Amercan Plywood Association certification to provide structural CLT in January of 2016. As demand has increased, the company is expanding Montana operations with a new Montana facility expected to be in operation early Spring of 2019 and has also announced plans for a new plant in Maine.
The new hardwood CLT product uses multiple species of low-grade Indiana hardwood that accounts for nearly 60% of the states hardwood harvests.
SmartLam received Amercan Plywood Association certification to provide structural CLT in January of 2016. As demand has increased, the company is expanding Montana operations with a new Montana facility expected to be in operation early Spring of 2019 and has also announced plans for a new plant in Maine.
SmartLam,
which estabished its reputation with softwood CLT, also recently gained recognition
as a supplier of hardwood CLT, an emerging technology, for a conversation
plinth designed by Bostons IDK design for the Cleo Rogers Memorial Library in
Columbus, IN, that complements a sculpture by Henry Moore. With support from Cummins
Engine for public buildings, the town south of Indianapolis has become a showcase
for internationally renowned architects, including the library’s designer, IM
Pei, and Eliel Saarinen who designed a nearby church.
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| Photo- IKD Architects, Boston |
The new hardwood CLT product uses multiple species of low-grade Indiana hardwood that accounts for nearly 60% of the states hardwood harvests.
Introduced
in Europe in the early 1990s, but invented some 20 years ealier, and later adopted
in Canada, CLT in the past several years has shown substantial growth as a
building material and method in the United States.
Brock Commons student housing in
Vancouver, BC at 174 feet and 18 stories, is currently considered the tallest mass timber building in the world,
combining CLT floors, reinforced concrete shear walls and glulam columns.
Carbon
12 in Portland is an eight story residential-office building that combines CLT
floor and roofs produced by Structuirlam of BC with glulam post and beams and steel
fame bracing. Although more than the five to six stories
in the IBC code, the building does not exceed the current IBC 85-foot height limit
for wood construction.
At
the federal Redstone Arsenal in Alabama, LendLease Corporation of Australia,
with decades of major construction around the world, has completed a Candlewood
Suites branded hotel to stringent government standards, which the company says involved laboratory testing for potential bomb blasts.
Thus
far most mass timber projects in the country have employed smaller scale use of
CLT combined with glulam and other materials in six floors or less. But the
recent emergence of a venture capital
financed startup in Silicon Valley has further raised the CLT profile and perhaps elevated the concrete industry’s conerns with
the code changes.
The code change debate has come to a head as the ad hoc
committee of the IBC spars with the concrete industry advocates,
in what might be termed a “they say, we say” dialogue over such CLT issues as fire safety, seismic and wind performance, and relative environmental advantages of the competing products.
The opposition effort is led by the Skokie, IL based Portland Cement Association
which lobbies for the concrete industry and has financed studies that raise
concerns about CLT.
One
thrust of the anti-CLT effort is pegged to the “Stop Tall Wood,” campaign, with
the same address as the PCA.
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| The campaign logo of the Portland Cement Association |
On
another front the PCA announced in mid-August that a study the organization
commissioned showed that 74% of Americans have concerns over “building stucture
and fire safety.” in wood construction.
In
a news release, PCA president and CEO Michael Ireland said, “It’s time
American’s (sic) were made aware of this threat, and that they can have a say
in whether the wood industry gets a fast-tracked path to being able to build
high-rise buildings across the country.”
A
bylined article distributed through Canada Newswire, a news release
distribution service, noted tha the OSU Peavy Hall problems “...raised questions
(again) about the risks of CLT.” At the bottom of the article was a link to the
Stop Tall Wood campaign. (www.stoptallwood.com) with the same Illinois address
as the Portland Cement Association.
The
International Code Council tallwood committee was scheduled to meet October 9-19 in Chicago, then hold public hearings on the first phase of changes in Richmond, VA the week of October 24-31.
The IBC committee addressed the issues in a report dated August 1,
partially titled a response to “...concerns raised on code proposals addressing
tall wood buildings.” Among participants, the committee said, were
engineers, architects, fire code and service officials and representatives of
materials and testing laboratories.
Half
of the 16 “concerns” addressed by the committee involved potential fire issues,
ranging from burn characteristics of mass timber to protection of sprinkler connectons and fire suppression response times.
In
its opening response of a 12-page report, the committee addressed “Concern 1”
that, “The changes are overreaching and lack true technical support for many
concepts proposed.”
The
committee responded that the proposed code changes resulted from “careful
analyis” of current codes, fire tests including those of the Alcohol, Tobacco
and Firearms laboratory and a “performance based approach to ensure that tall
wood buildings provide similar performance compared to current construction
types allowed by the code.”
In
particular the committee wrote that the code revisions took into consideration
performance of mass timber when tested similarly to existing construction
methods.
Only
in the past decade or less has CLT construction established a foothold in the
United States. Much of the early CLT materials came from Canada, where
Structurlam of Penticton, BC supplied a number of US projects.
In addition to Montana's SmartLam, the oldest CLT producer in the states, new entrants could include a mill in northwestern Washington, Vaagens, that announced it will begin CLT
production in the near future.
As
might be predicted CLT also attracted attention from Silicon Valley, as relative
newcomer Katerra entered the market with a reported $1.2 billion in financing only three years ago and ramped up panel
production at its original Phoenix facility while announcing a major new one planned in
Spokane Valley, WA. Permits were issued in late 2017 for a $35 million, 250,000
square foot that could employ 150. The company website said in October that the Spokane plant and
another with more than 500,000 square feet in Tracy, CA would come online in
early 2019.
Although
boasting a governing board of blue chip venture capitalists, recent published reports
from Silicon Valley media in August said Katerra, which had drawn top talent
from Tesla and other manufacturers, had experienced substantial executive
turnover. The reports noted that some managers had little construction
experience and the company faced production delays as well as delivery of
panels that didn’t fit design specifications.
Among
the most active Northwest supporters of CLT is Forterra, Seattle-based
environmental and conservation nonporfit which has sponsored numerous
conferences and reports on benefits of the production method.
The
state of Washington has also encouraged construction of new schools with CLT,
easing the way with a state law to expedite permitting. In its 2016 capital
budget the legislature provided $5.5 million for four classroom pilot projects
using CLT. DR Johnson of Oregon provided the CLT for those structures.
Although
CLT will likely continue to win support in the United States, some observers
believe smaller “short wood” buildings, such as the Washington schools and
buildings no more than five to six stories will lead the way in the near term.
With
the problems experienced in the OSU Peavy Hall project, there will also be
increased scrutiny by industry professionals and enhanced attention to quality
control as new producers work to establish track records.
But as mass timber producers and technology mature in the country, albeit with occasional glitches, few in the construction industry would expect that CLT will fade away.
But as mass timber producers and technology mature in the country, albeit with occasional glitches, few in the construction industry would expect that CLT will fade away.
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