Interlocking Cross Laminated Timber Could Use Up Square Miles of Beetle-Killed Lumber, and Look Gorgeous, Too

itac/Promo image

The Mountain Pine Beetle is killing trees across North America, including up to 44% of Colorado's forests. If there was any infrastructure investment to be made right now, I would have thought it would be to set up a pile of cross-laminated timber factories fast, and put people to work churning out panels at a standard size and stockpiling them; CLT is strong, fire-resistant, it sequesters carbon dioxide and it makes very pretty buildings.

At the University of Utah's Integrated Technology in Architecture Center, (ITAC) they are working on a modification of the design of CLT for the American market, namely figuring out how to make it cheaper. (See full team credits at bottom) Ryan Smith of ITAC writes:

Unlike other solid wood panel systems, ICLT utilizes no fasteners and no adhesives. Cross-laminated timber (CLT) for North American markets has historically not been feasible due to relative high cost of fabrication, however, developments in CNC technology and sourcing waste and beetle kill standing dead pine from the intermountain region presents a viable option for creating solid wood technology. ICLT is a cost competitive technology for the 3-9 story commercial structures replacing concrete and steel construction, reducing ecological footprint, and increasing indoor air quality of future buildings.

Instead of using expensive and possibly VOC-heavy glues or expensive stainless steel fasteners, they use tongue and groove joints, shown above on the end-to-end pieces or dovetail joints, on the crossing pieces, to hold it all together. They don't need fancy presses like they do for the glued CLT either, and it can be "disassembled at end of life to be repurposed in the building material supply chain." It is evidently simple enough to do that "standard mills and timber fabricators looking to diversify their product offering may produce ICLT with existing infrastructure and equipment.

I would not have thought that it would be as strong as conventional CLT, but it was. In fact it was stronger that CLT and even insulated concrete form walls.

Ryan Smith of ITAC says that "ICLT is currently in the development, testing, and code acceptance research phase in preparation for market acceptance in the next three – five years." That's a shame; I want it now.

Full credits:

ITAC University of Utah
Euclid Timber LLC and Hundegger USA
Brigham Young Civil Engineering
Acute Engineering
U.Idaho Forest Products
USDA Forest Products Laboratory