Cross-laminated timber (CLT) turns 100

Cross-laminated timber (CLT) turns 100

By Dan Roche • August 23, 2023 • Architecture, News

Cross-laminated timber is commonly believed to have been invented in Europe in the 1990s, a mistruth. (Oregon Department of Forestry/Flickr/CC BY 2.0/Edited by AN)

CLT (cross-laminated timber) is a buzzword these days. Architects and building industry leaders tout it as a more environmentally-sound alternative to steel and concrete that can be used to make a variety of building types: big and small.

In 2019, architects marveled at Norway’s Mjøstårnet by Voll Arkitekter, the world’s largest CLT tower at the time, which according to the CTBUH was recently surpassed by Ascent, a 284-foot tower in Milwaukee, Wisconsin designed by Korb & Associates Architects. Since then, even more CLT high-rises have sprouted up in Singapore, Vancouver, Melbourne, Rotterdam, and other cities.

Regardless of CLT’s seemingly recent popularity, the technology itself is a century old, and just celebrated its 100th birthday this August. And despite general consensus that CLT was invented in the 1990s in Europe, the technology was in fact first conceived in the good ole U.S.A.

The first patent application for CLT was submitted on March 17, 1920. (Courtesy U.S. Patent and Trademark Office)

On March 17, 1920, two residents of Tacoma, Washington, Frank J. Wars and Robert L. Watts, filed a patent application for a “new and useful improvement in Composite Lumber.” The application by Wars and Watts stated: “The strips or boards thus formed are then cut into suitable lengths and such lengths are then superimposed one above the other so as to form a plurality of layers, with the grain of the wood in one layer running at an angle to the grain of the wood in the adjacent layer.”

The patent application by Watts and Wars was approved on August 21, 1923. It’s unclear whatever came of the business partners, but the long deceased Tacoma industrialists may take comfort in the fact that CLT usage is expected to triple by 2030, according to Quince Market Insights . Market analysts note that CLT is presently a $1.66 billion industry in the U.S. but in just seven years, that number could be $4.24 billion.