We get so excited about Cross-Laminated Timber (CLT), the fancy plywood on steroids that we talk so much about on TreeHugger. But in fact, there is a much older technology for building with wood, that warehouses and factories were built out of 150 years ago with a fancy new name: Nail-Laminated Timber, or NLT. It used to be known as heavy timber or mill decking and is drop-dead simple: you just nail a pile of lumber together and voila.
Lucas Epp of Structurecraft stunned the audience in a presentation at the Wood Solutions Fair in Toronto, showing extraordinary projects built out of the stuff. Because while CLT is great stuff, it's pretty new in North America, it's expensive, and it's not fully understood by the building inspectors. Whereas if you are doing a simple span, NLT does the job just fine, It's a lot cheaper, can be made by anyone with a hammer and has been in the building codes forever. As Structurecraft explains:
In much the same way as tongue-and-groove wood decking, NLT is sanctioned by building codes in both Canada and the USA (NBCC and the IBC). NLT qualifies as Heavy Timber as long as it is "well-spiked together" and the depth is at least 64mm for a roof and 89mm for a floor (see NBCC 18.104.22.168 4b/6b and IBC 602.4.6.1). As such, it does not require an "alternative solution" application.
It's now being used in a 210,000 square foot, seven storey office building in Minneapolis, where the developer, Hines, wanted "the warmth of wood and the embrace of green construction techniques and materials" to attract the tech and creative sector of the market. It also goes together much faster than a conventional steel or concrete building.
The teams’ decision to go with NLT (nail-laminated timber) was formed on a number of factors including aesthetics, structural advantages, lower cost, and faster procurement times.
Heavy timber office and warehouse construction fell out of favor early in the 20th century after major fires in a number of cities caused the switch to concrete and steel noncombustible construction. The development of effective sprinklers has reduced that risk, and concerns about the carbon footprint of concrete have made renewable wood look a lot more attractive.
Designed by Mr. Tall Wood himself, Michael Green, the wood itself is a lot more attractive to look at too. And it's not just for simple flat spans like in the Hines T3 building;
This swoopy roof is was built for a pavilion in China; no special made-up panels were imported, they just went to the lumber yard and bought what they needed.
This roof over Chilliwack Secondary School looks so good because they used two different sizes of wood.
This panel gets held up by the clever use of universal joints.
This school got assembled in five days.
This cantilever stays up thanks to carefully engineered diagonally placed nails.
Really, I am not exaggerating when I say that the audience was stunned by Structurecraft's Engineering and 3D manager Lucas Epp's presentation, to see such amazing work all made from a bunch of dumb planks nailed together. What a remarkable comeback for a great old technology. More at Structurecraft.