Can they really build office buildings out of wood? Science Cafe will find out!

  • A rendering of 90 Arboretum Ave. at the Pease Tradeport, which will be the state’s first engineered-wood building. Courtesy SGA Architects

Monitor staff
Published: 11/19/2019 8:32:08 AM

At Science Cafe we often discuss the cutting-edgiest of cutting-edge technology. That’s why on Wednesday we’re going to talk about making buildings out of – wait for it – wood.

What a concept!

OK, enough levity. The latest of our monthly geeky-conversations-in-a-restaurant sessions will be taking questions from the crowd about a new way of using trees to make buildings that goes by a variety of terms including mass timber, cross-laminated timber and, my favorite, engineered wood. 

Instead of using discrete pieces of single trees, like a 2x4 or something from a post-and-beam home, engineered wood glues together smaller pieces of lumber to build large items that can replace steel beams, flooring, or concrete.

There are plenty of advantages to this approach (and, yes, some disad vantages) said Matt Formicola of SGA Architects, project manager for what will be the first engineered-lumber building in New Hampshire, 90 Arboretum Drive at the Pease Tradeport. Here’s a big advantage that us non-developers wouldn’t think of: Time.

“The main difference is the speed of construction. We are able to put this building up a lot quicker,” said Formicola.

An example: The walls of the elevator shatft and stair shaft are made of cross-laminated timber rather than poured concrete. “It takes 3 or 4 days to put that up, compared to a couple weeks for a concrete shaft,” he said.

Since time is money, this speed goes a long way toward covering the generally higher cost of engineered lumber, which is so new in North America that few places are making it. 90 Arboretum will be built with wood made in Canada.

Creating pieces of wood by gluing together smaller pieces isn't new, of course, but we’re not talking about plywood and that crummy wall covering known as particleboard. Engineered wood uses a variety of technologies and designs to create beams or sheets that are very strong, fire resistant and can have many different shapes. It is already being used as framing and for internal components in mid-rise buildings in Europe, some as tall as 14 stories.

The technology has gotten so good that building codes around the world are being updated to allow more use of mass timber. New Hampshire, as is often the case with regulation, is behind this curve, since we only just decided to adopt national building codes from 2015. 

Formicola is not just project manager for the 3-story, 72,000-square-foot office building at Pease, he’s one of the panelists who will be on hand at Makris Lobster and Steak House to answer your questions Wednesday. Science Cafe NH is nothing if not timely.

Chances are that you, like me, had hardly heard of mass timber a year ago. These days its profile is much higher.

That’s mostly due to the climate crisis, which has raised interest in a major benefit of mass timber: It takes the carbon in trees and locks it into midrise and highrise buildings for decades. By contrast, steel and especially concrete release carbon by the boatload during their manufacture. Switching construction to mass timber is often cited as one of the big steps that we need to take to keep climate change from becoming even worse than it is proving to be. 

There’s another benefit for New Hampshire, since mass timber promises to create a new market for our logging industry. Two forestry folks will be part of the SCNH panel for that reason.

Formicola makes it clear that CLT isn’t magic. 

“Acoustically it’s a pretty good material, but in terms of vibration – walking on it – that can be an issue. You usually want to do an acoustic mat” as part of the layers, he said.

Weight is another issue – or, rather, lack of weight compared to steel or concrete.

“The building is very light, so we had to have a pretty heavy foundation to hold it down for wind loads,” he said. “Shear is also a concern – don’t want the building racking back and forth … we have to design for that.”

Ad then there’s the fact that you can’t drill holes in wood beams once they’re installed, because that harms their weight-bearing ability. So you have to design the building really well in advance to make sure you’re got a place for all the pipes and wires.

And what about fire? That was probably your first thought when you heard about high-rises made of wood.

My house would burn fast because its frame is made of skinny pieces of wood – 2x4s and 2x8s and 3x6s and the like. These have a very high surface-to-volume ratio, so there are lots of places for oxygen to fuel flames.

Engineered wood beams, on the other hand, are huge – as much as three feet thick, so the ratio is much smaller. As a result, they char slowly rather than burst into flame; properly designed, they have a one-hour fire rating, which is more than suitable for tall buildings.

But don’t take my word for it. Show up Wednesday and ask people who actually know. You might be getting in on the ground floor – ha! get it? – of a big new trend.

(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)

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IF YOU GO BOX

Science Cafe NH will talk about mass timber, a.k.a. engineered wood, at its monthly session Wednesday. Among the panelists will be the project manager of the first mass timber building in New Hampshire to answer questions about this method of building wood structures that can fight climate change as well as help the logging industry. Reservations are required, 225-7665, with seating preference for those who buy $18 buffet dinner. 

Where: Makris Lobster and Steak House, 354 Sheep Davis Rd., Concord.

When: Wednesday, Nov. 20, 6 – 8 p.m. Buffet dinner is served starting at 5 p.m.

For more information: ScienceCafeNH.org.

 




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