It has been more than 80 years since a tree species in the Northeast has been added to the list of those meeting construction industry standards, but that list has just grown by one. Lumber milled from Norway spruce was approved this fall by the National Lumber Graders Association.
Norway spruce is not native to the United States, though it may feel that way, as about three billion of these trees were planted by the Civilian Conservation Corps in the 1930s, mostly in Maine, New York, Wisconsin, and Pennsylvania. Since that time, Norway spruce has only been used for pulp, because it had never been tested and graded for its strength and structural integrity as is required by building codes.
“Testing is federally mandated by building codes to certify that lumber is of sufficient quality,” explained Stephen Shaler, director of the School of Forest Resources at the University of Maine. “Norway spruce had been tested in Europe, but we can’t use that data because we have different climate and soils, and our trees may be a different genetic strain.”
Shaler led a team of staff and students in conducting an extensive series of tests on Norway spruce during the winter of 2015–2016. The evaluation included bending 1,200 boards to their breaking points and gripping an additional 600 boards at either end and pulling them apart. The lumber they tested was milled into 2x4s, 2x6s, and 2x8s from trees selected and graded by the Northeast Lumber Manufacturers Association from sites in four states.
“We put each board into a testing machine, attached electronics to measure their flexion, and then bent them until they broke,” explained Shaler.
After each board was broken, graders from the Lumber Manufacturers Association examined the pieces to determine where and why they broke. Not every piece was the same, of course, so there was a lot of statistics involved in calculating whether Norway spruce wood is safe for use in construction, Shaler said. He submitted a report last winter to the Lumber Graders Association, which made its final decision in September.
Based on the tests, Shaler was confident that the national agency would agree that Norway spruce measures up to all the other construction-approved species in the Northeast. The agency’s approval “means that landowners will have a new market for their Norway spruce, that sawmills will have another source of material they can process, and that the mills will have access to a lot of good-quality, large trees they didn’t have before,” he said.
The University of Maine was selected to conduct the testing because its testing laboratory is accredited by the International Accreditation Service, so its results are accepted by state and federal building codes. The facility, called the Advanced Structures and Composites Center, of which Shaler is associate director, is involved in finding new uses and markets for wood. It is currently conducting studies of cross-laminated timber, wood-plastic composites, bioenergy, and applications for nano cellulose.