Home Building Technology, Part XV: The Rebirth of Wood

Issue #18320 - March 2026 | Page #10

By Joe Kannapell

Wood was not held in high regard in the truss drafting department where I began working. Our fabricator customers often wanted their trusses designed with “old lumber,” meaning the obsolete size of 1-5/8” x 3-5/8”, even though the 1.5” x 3.5” size had been in force for several years. Not only did this imply “cheating” to gain the 12% higher values for their truss designs, but it also made extra work for the draftsmen, causing them to remark, “One day the 2x4 will shrink to nothing.” This dismissive view of the product we staked our reputation upon was compounded by them having to rework designs due to the unavailability of the Douglas Fir lumber that customers had originally specified. Moreover, this situation was not likely to improve, as Congress had resoundingly defeated a 1970 bill to increase logging in national forests. None of the alternate species that fabricators suggested would work nearly as well, especially Spruce, which the draftsmen agreed was “junk.” As a last resort, fabricators would hesitatingly suggest Yellow Pine, which they feared “would go wild” as soon as they broke the bands on a unit. In short, if you listened to the cacophony at Hydro-Air Engineering in 1970, lumber was bad and getting worse. [For all images, See PDF or View in Full Issue.]

That made sense, since my structural engineering classes made no mention of wood, which seemed to be a relic of the past. Even though the workability of wood enabled settlers to erect great cities in record times, and was currently the staple of housing construction, its relatively low strength and its vulnerability to fire apparently outweighed its usefulness as a structural material. Most of my classmates wanted to work in the nice offices of a Civil or Structural Engineering firm, as I had at two firms during school. One designed mainly steel-reinforced concrete structures, while the other designed steel buildings. Apparently, that was where actual engineering was.

I got the same feeling when I had first reported for work in the dingy, industrial space occupied by Hydro-Air, a stone’s throw from a junkyard. I worked as a programmer behind a dozen men at drafting boards, near the back of a large open room, upstairs from a hydraulic machinery operation. Our one registered engineer and his two senior designers sat behind windowed partitions against the back wall of the room, chain smoking.

Later, I tested trusses in our basement stamping plant underneath the heavy wood beams and plank flooring of an early century mill building. This type of antiquated structure once housed the bulk of manufacturing and warehousing and was not required to have fire sprinklers. Nevertheless, our owner, Walter Moehlenpah, was deathly afraid that one of our workers would start a conflagration with a lit cigarette and we’d be out of business. That’s why he moved us to a modern concrete and steel bar joist building as soon as he had the money, in another, and ironic, deprecation of wood construction.

As housing starts doubled in the early 1970s, more lumber supply disruptions occurred, and along with them, more concerns about lumber quality arose. The specified moisture content of Southern Pine lumber was increased from 15% to 19%, which seemed to increase the propensity of bow, warp, and twist. As housing starts waned in the mid-1970s, fabricators sought commercial jobs and a few of them found themselves in litigation arising from first-generation fire treatments that corroded connector plates. Then, in 1977, a severe and sudden reduction of 2x8, 2x10, and 2x12 lumber values rocked the truss industry, creating even more skepticism around the product we were certifying. Fortunately, the lumber producers were beginning to address the challenges faced by our industry.

In the same year I started at Hydro-Air, Kay Kahus began working in the field for the Western Wood Products Association (WWPA). There he learned the ineffectiveness of visually graded lumber, and this experience prompted his later move to Weyerhaeuser to market a promising new product, machine stress rated (MSR) lumber. After several years of testing and evaluation, Weyerhaeuser installed its first MSR machine in 1979 to supply chord material for TrusJoist’s TJL product. Subsequently, I invited Kay to speak with Hydro-Air fabricators, and he was enthusiastically received. He also met separately with the Component Manufacturing Council (CMC), including Jack Littfin of Littfin Lumber and Dave Chambers of TruTrus, as well as other truss-related suppliers.

Although the engineering community waited in great anticipation for MSR to become widely available, only Spruce-Pine-Fir (SPF) from Canadian mills initially flowed into the U.S. The uniformity and stability of this product quickly won over component manufacturers and addressed many of the quality and strength issues that plagued Spruce and other visually graded species. Particularly significant was the fact that the lumber producers began to listen to the concerns of the truss industry in the 1970s. As reported by the MSR Lumber Producers Council, by 1979, some of the larger producers even sent field engineers to work with truss plants and truss plate designers.

While the development and successful deployment of MSR was a win for a minority of U.S. component manufacturers, it began to reverse some of the negative perceptions about the future of the product upon which our livelihood depended. Although there would be no quick return of lumber framing in heavy industrial structures, wood trusses were increasingly favored over steel joists in commercial and large apartment construction. This rebirth of our wood resource was made possible by the demands of the truss industry and the newly found desire of the lumber industry to develop products to supply those demands. And there would be much more to come.