Oregon State University is pointing to a manufacturing glitch as the culprit in the failure of a cross-laminated timber panel in a campus construction project last month but says the problem has been fixed and installation of CLT panels will resume in the next few weeks.
A 4-foot-by-20-foot section of subflooring gave way and fell March 14 in the George W. Peavy Forest Science Center when the CLT panel reportedly delaminated at one end.
No one was hurt in the incident, but general contractor Andersen Construction put a hold on installing any more of the massive slabs of laminated 2-by-6’s pending an investigation of what went wrong.
On Thursday, the university announced that an evaluation of the manufacturing process showed the DR Johnson plant in Riddle had used preheated wood in assembling some of the panels for the project. That resulted in premature curing of the adhesive and poor bonding between the layers, ultimately causing one panel to fail.
KPFF Consulting Engineers, a Seattle-based company hired by the university, participated in the investigation along with Andersen Construction, DR Johnson and the American Plywood Association, which is involved in certifying and setting performance standards for CLT panels. DR Johnson is an association member.
An American Plywood Association statement issued last week said the problem was introduced by a process change and that DR Johnson has now corrected the issue and implemented additional quality controls.
Production of additional CLT panels for the project will begin immediately using the improved process and Andersen Construction is expected to begin installing them over the next few weeks, the university said on Thursday.
In portions of the building where CLT panels had already been installed, work will remain on hold until core sample testing is complete.
“They’re looking for any evidence of delamination,” OSU Vice President for Marketing and University Relations Steve Clark said. If a problem is found, he added, “the project engineer would recommend a project fix that would provide for the safety and reliability of the building.”
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Clark said completion of the three-story, 80,000-square-foot laboratory and classroom building has been set back by about three months, to the summer of 2019. OSU is shielded from any additional costs caused by the delay by a guaranteed-bid construction contract with Andersen.
The project was controversial long before the March 14 mishap.
The George W. Peavy Forest Science Center, the first phase of a planned three-building Oregon Forest Science Complex, will become the new home of the OSU College of Forestry, which used to reside in Peavy Hall.
Many of the college’s faculty and students objected when plans were announced to tear down the old Peavy, which they said could have been renovated for far less money.
The Oregon Forest Science Complex has been dogged by delays and cost overruns, with the project’s budget ballooning by more than 30 percent from $60 million to $79 million. Much of the cost increase is being borne by the college, which has had to borrow money from university accounts, ramp up logging operations on college-owned forests and go back to donors for additional cash.
Peavy is also viewed as something of a litmus test for cross-laminated timber and other engineered wood products used in mass-timber construction. Proponents say CLT panels can be assembled quickly on-site and are strong enough to be used as structural elements in midrise and even highrise buildings.
If the technology takes off in the United States, it could be a boon for Oregon’s wood products sector, but questions about reliability could be a setback to those hopes.
Clark said OSU remains committed to completing the project and insisted it has strong support within the College of Forestry.
“It’s still a very essential project to the university and will be a testament to the wood products industry in the Pacific Northwest, so they are very excited,” he said.