CORVALLIS, Ore. (AP) — The completion date for the new College of Forestry building at Oregon State University has been pushed back another three months.

the university is now looking to have the building finished by fall 2019.

The three-story, 80,000-square-foot building was originally targeted for completion in the fall of 2017, but that timeline has been repeatedly modified amid rising construction costs and other issues.

Construction was slowed in March after a large section of subflooring made of cross-laminated timber gave way, and the university brought in outside consulting engineers to determine what went wrong.

The issue was traced to a glitch in the manufacturing process at a mill in Riddle, where preheating of 2-by-6 boards resulted in improper curing of adhesives holding the cross-laminated layers of wood together.

Though the manufacturer fixed the problem, inspectors had to evaluate the CLT panels that had already been installed.

Before the panel failure, the target completion date had already been pushed back to spring of 2019.

In late May, when general contractor Andersen Construction began removing some of the massive CLT panels for replacement, it was revised to summer. The testing-and-replacement process has taken longer than expected, prompting the new estimate.

Clark said 40 faulty panels have been replaced and another 45 have been identified for replacement.
Analysis of test data and quality control reports is still being done on some of the remaining panels, a process expected to take about two more weeks.

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A section of subflooring failed last week during construction of the $79.5 million new Peavy Hall at Oregon State University in Corvallis.

A 4-foot-by-20-foot cross-laminated timber (CLT) panel, made up of five layers of 2-by-6 Douglas fir boards glued together in a crisscross pattern, delaminated at one end and fell from the third floor to the second on March 14, according to Steve Clark, OSU vice president of university relations and marketing. No one was injured, he said.

“There was no one in the work area at that time,” he said.

The CLT panel that fell was manufactured by D.R. Johnson Lumber Co. of Riddle, the Corvallis Gazette-Times reported. Representatives of D.R. Johnson declined Wednesday to comment on the incident, referring all queries to OSU officials.

Construction at the site involving CLT installation has been suspended by general contractor Andersen Construction, Clark said, but other work on the building is continuing while an investigation into the collapse is carried out.

“That’s what we understand (happened),” Clark said, referring to delamination. “We have a third-party engineering firm evaluating what happened and what caused the failure. And we’re hoping that the investigation by the third-party firm will be completed next week.”

The damaged panel, which was prefabricated off-site, was replaced within 36 hours of the initial collapse, Clark added.

“All the (CLT) panels in the building were braced with shoring, which is a standard practice with concrete and steel, but in this case we did it as a safety precaution,” he said. “In construction, even using conventional methods, from time to time there are issues. And contractors, engineers and designers, they identify solutions and implement that solution. We’re identifying the cause of the failure and we’re identifying any other components that may be compromised.”

The three-story Peavy Hall is replacing the original Peavy Hall on the same site. It is intended to become the centerpiece of the College of Forestry and a demonstration of contemporary timber-based building techniques.

The new hall is also being built using a so-called “rocking wall” intended to dampen seismic vibrations and render the structure able to withstand an earthquake and protect its occupants.

Clark said it is too early to know how much it will cost to repair the damage. When asked whether OSU officials have any reservations about further use of CLT in the building, he responded, “We have none whatsoever.

“We’re committed to CLT and we believe it’s been demonstrated across Europe and Canada as a safe construction method,” he said. “Actually, this university has helped bring CLT to testing and documentation and been a champion of it, so we’re completely in support of it.”

For mass-timber buildings, solid wood panels are used to frame walls and floors, including the roof. CLT is meant to replace concrete for those uses, thereby saving weight and cost. The construction method only recently has begun to gain acceptance in the United States.

Many industry professionals asked Wednesday about the incident were hesitant to offer any insight into the panel collapse. Several said it was too early to speculate and there are too many variables to sort through to identify a cause. One representative of a manufacturer of CLT products lamented the incident could be “disastrous” for the fledgling mass-timber industry, while others in the industry shied away from the topic altogether.

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