Mass Timber is in for massive change

Making a panel
CC BY 2.0 Lloyd Alter

We talk a lot about the wonders of wood construction but really, the industry is just getting started.

Mass Timber is all the rage in the construction industry and many magazines and websites are full of headlines like “first mass-timber building constructed in Minnesota” or wherever, when in fact, people have been building with mass timber for centuries; just about every funky old warehouse in North America is mass timber, built of 2x8s or 2x10s on 2 inch spacing, nailed one to another. That’s now known as NLT or nail laminated timber. I was blown away by a presentation a few years ago by engineer Lucas Epp of StructureCraft in British Columbia, showing how the company is doing amazing things with it, so I went out to visit.


Installation of StructureCraft Office and Shop - Time Lapse (part 2 - new footage) from StructureCraft on Vimeo.

StructureCraft recently opened a new factory in Abbotsford, British Columbia to make a different mass timber product, Dowel Laminated Timber (DLT). The factory itself is a bit of a wooden wonder; it is built out of prefabricated components and after the foundations were finished, the wood section was assembled in just five days. It does things that I wouldn’t have thought were possible in wood; the wall panels support glue-laminated beams that hold up prefabricated roof panels. The walls and columns are strong enough to support 10 ton travelling cranes.

DLT machineDLT machine/ Lloyd Alter/CC BY 2.0

Inside, half the factory is used for manufacturing DLT panels; lumber is finger-jointed together into lengths up to 60 feet, run through a milling machine to get the desired finish, then stacked up side by each to be drilled and dowelled with very dry hardwood dowels, which then expand as moisture equalizes and then hold the panels together. The other half of the factory is used for fabricating other complex timber structures.

acoustcDLT with acoustic absorption/ Lloyd Alter /CC BY 2.0

The DLT is impressive stuff; it can be milled to a number of different profiles with different architectural properties, depending on aesthetics or acoustics. It can have that look of the old warehouse, or a different, modern finish. But unlike the old NLT or mill decking, it is a consistent, planed product. The panels can be huge (12’ x 60’). Structurally, DLT is more efficient than CLT for floors and roofs with one-way spans between beams, but it is not as flexible as CLT for two-way spans or cantilevers; however, it is quite a bit cheaper to manufacture, easier to engineer and get approvals because it has been in the building codes since there were building codes.


Michael Green Talk – The Future of Wood & Dowel Laminated Timber from StructureCraft on Vimeo.

NLT was used in Michael Green’s T3 building in Minneapolis, but DLT is the new NLT; it is not as labor intensive to make, it can be milled on a CNC machine and recycled more easily because there are no nails in it. But DLT is not intended to replace CLT – rather it is just another option in the mass timber toolbox.

Lucas EppLucas Epp/ Photo Lloyd Alter/CC BY 2.0

When they built their factory, StructureCraft didn’t build it out of their CLT or NLT or DLT products; they built it out of prefabricated panels built up out of wood studs- they are simpler and cheaper and use less wood. CLT may be fashionable, but as Lucas Epp noted, “sustainability is about using as little material as possible.” (That’s why I go on about what they are doing in Sweden with panelized, computerized, roboticized wood frame). You pick the right tool for the job.

Inside factoryInside factory, not the DLT side/ Lloyd Alter/CC BY 2.0

My understanding before visiting the factory in Abbotsford was that StructureCraft was in the wood business; in fact, they are in the engineering business and the DLT is part of their toolbox. The company was founded by Gerry Epp, formerly of Fast + Epp, because nobody was around who would be willing to produce and install the timber components they needed for the designs they were engineering for architects like the late great Bing Thom. Gerry’s son Lucas spent years in the UK with Buro Happold working on projects designed by Zaha Hadid and Norman Foster. Lucas is using the same tools that Gehry or Zaha used for parametric design, like Rhino and Grasshopper, to build totally amazing things out of wood, which Lucas says is still one of the least understood building materials. They are pushing it to its very limits.

Dome for China© StructureCraft

They are building giant domes in China, swoopy ceilings in Calgary for Snohetta, and re-thinking the way one designs with wood.

complex assembly© StructureCraft/ there is incredible complexity buried in that wood

Even what look like relatively ordinary buildings have incredible complexity in today’s world where buildings have to withstand seismic, fire and wind loads. Epp notes that prior to the Christchurch earthquake, buildings were designed for life safety and most did what they were designed to do- protect the occupants. But then the buildings were tilted or otherwise useless and had to be taken down; now, timber engineers like StructureCraft are designing buildings to be resilient; to rock and roll and recover from the earthquake instead of just stay up. This is incredible, invisible engineering.

roof in china© StructureCraft

We go on about how wood from properly managed forests is the most sustainable building material, being renewable and storing carbon for the life of the building. But good engineering is about using materials wisely, and using as little of them as possible. Fast + Epp and StructureCraft engineered the roof of the Richmond Olympic Skating Oval out of a bunch of beetle-damaged 2x4s and StructureCraft is now designing 300 foot wide domes in China that seem to be built out of air rather than wood. This truly is the building material of the future.

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