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Results from two recent tests of cross-laminated timber panels, for fire resistance and flame spread, show that the mass timber product is closer to gaining recognition as an acceptable building material, proponents claim.

The tests were commissioned by D.R. Johnson, the only company in the country that is certified to sell CLT as a building product. Valerie Johnson, president of the Riddle-based company, said the tests are an important step forward for CLT.

鈥淚t’s really quite significant that our panel is of such quality that it’s flame-resistant,鈥� she said. 鈥淚t’s really a terrific omen for the process of developing mass timber for wood construction systems.鈥�

Tests of CLT and mass timber, or engineered wood, products have taken place in Europe for decades, Johnson said, and more will follow in the U.S.

鈥淲e had to go through rigorous structure strength testing just to be certified to sell panels as structural products,鈥� she said. 鈥淲e will also go through blast testing and high-wind testing. It’s a very strong product and when used well it has a tremendous amount of promise.鈥�

The flame spread test was conducted by QAI Laboratories’ office in Rancho Cucamonga, California, using the standard flame spread and smoke density classification tests in accordance with methods outlined by the American Society for Testing and Materials, according to a statement from D.R. Johnson. The test identified the rate of spread of fire across the material and gave it the highest rating, meaning there was 鈥渕inimal spread of fire across the building material over the test’s standard time period.鈥�

The fire resistance test was performed by the Southwest Research Institute in San Antonio, Texas, according to D.R. Johnson. The test evaluated the duration for which a building material will contain a fire or retain its structural integrity during a predetermined fire exposure time; the panel passed the test.

D.R. Johnson is the first CLT supplier to have a panel pass both tests in the U.S., according to David Barber, fire protection engineer and principal at engineering firm Arup in Washington, D.C.

鈥淚t’s good for them, but also very helpful for the (CLT) industry,鈥� he said. 鈥淪ome of the missing parts of the puzzle for using CLT was the lack of fire testing because most of the fire testing is carried overseas. This is part of the process where this product can be used more in the U.S. even though it’s been used extensively in other countries.鈥�

Meanwhile, other tests of CLT are being conducted by a team led by Thomas Robinson, founding principal of Lever Architecture, thanks to a $1.5 million grant it won from the U.S. Department of Agriculture. Those tests will evaluate fire, acoustical and seismic resiliency systems, and help facilitate construction of the 12-story Framework tower in the Pearl District; it is expected to become one of the country’s first modern timber high-rise buildings.

In June, Robinson explained that because current building codes don’t allow for a 12-story mass timber building, the tests will help the Framework tower meet basic code requirements.

Timm Locke, director of forest products for the Oregon Forest Resources Institute, said the recent tests are an incremental but necessary step for CLT to potentially stimulate the timber industry.

鈥淎ny new product needs to pass tests to meet safety requirements of buildings, and they passed and it’s helpful,鈥� he said. 鈥淲hen architects want to use it in a building, they can point to those tests and say those are the test results for that particular product.鈥�

Additional tests will give CLT more validity among builders, Locke said.

鈥淔ire and safety are the most commonly cited question marks, and people in the CLT and mass timber industry are finding answers for those products.鈥�

The use of CLT has drawn heavy criticism from the National Ready Mixed Concrete Association, however. Lionel Lemay, senior vice president of sustainable development at the NRMCA, told the 91视频 in May that the wood industry 鈥渄oes not like to cite scientific research because it doesn’t support their argument.鈥�

Kevin Lawlor of Build With Strength, a coalition of the NRMCA, claimed that despite testing, CLT cannot match concrete for fire safety.

鈥淚’m sure lab studies can show varying degrees of safety with different wood products, but I’d say no lab study can match the real life fire resistance of concrete products,鈥� he said.

Lawlor added that full-scale testing and fires in completed buildings 鈥渉ave demonstrated that CLT does not perform very well in fires.鈥�

But scientific testing will continue, Johnson said. Meanwhile, Oregon State University’s College of Forestry is testing inland tree species to see whether they can be used to produce CLT; currently, it’s made from Douglas fir trees.

鈥淚t’s exciting to see, as we get these positive test results, just what the potential might be,鈥� Johnson said.