Sustainable Building Effort Reaches New Heights With Wooden Skyscrapers (knowablemagazine.org) 26
The University of Toronto is constructing a 14-story building using mass timber, one of the largest and most recent projects to employ this innovative building technology. "Mass timber is an appealing alternative to energy-intensive concrete and steel, which together account for almost 15 percent of global carbon dioxide emissions," reports Knowable Magazine. "Though experts are still debating mass timber's role in fighting climate change, many are betting it's better for the environment than current approaches to construction. It relies on wood, after all, a renewable resource." From the report: Today, the tallest mass timber building is the 25-story Ascent skyscraper in Milwaukee, completed in 2022. As of that year, there were 84 mass timber buildings eight stories or higher either built or under construction worldwide, with another 55 proposed. Seventy percent of the existing and future buildings were in Europe, about 20 percent in North America and the rest in Australia and Asia, according to a report (PDF) from the Council on Tall Buildings and Urban Habitat. When you include smaller buildings, at least 1,700 mass timber buildings had been constructed in the United States alone as of 2023. [...]
In principle, mass timber is like plywood but on a much larger scale: The smaller pieces are layered and glued together under pressure in large specialized presses. Today, beams up to 50 meters long, usually made of what's called glue-laminated timber, or glulam, can replace steel elements. Panels up to 50 centimeters thick, typically cross-laminated timber, or CLT, replace concrete for walls and floors. These wood composites can be surprisingly strong -- stronger than steel by weight. But a mass timber element must be bulkier to achieve that same strength. As a building gets higher, the wooden supports must get thicker; at some point, they simply take up too much space. So for taller mass timber buildings, including the Ascent skyscraper, architects often turn to a combination of wood, steel and concrete.
In principle, mass timber is like plywood but on a much larger scale: The smaller pieces are layered and glued together under pressure in large specialized presses. Today, beams up to 50 meters long, usually made of what's called glue-laminated timber, or glulam, can replace steel elements. Panels up to 50 centimeters thick, typically cross-laminated timber, or CLT, replace concrete for walls and floors. These wood composites can be surprisingly strong -- stronger than steel by weight. But a mass timber element must be bulkier to achieve that same strength. As a building gets higher, the wooden supports must get thicker; at some point, they simply take up too much space. So for taller mass timber buildings, including the Ascent skyscraper, architects often turn to a combination of wood, steel and concrete.
No thanks (Score:2)
I live in a three story wood frame building and the cheapness and lightness of this structure worries me daily. The whole building rattles when the outside door closes. My dishes clink together when people go up stairs. You can hear everything.
Sure, if you build an experimental structure with no cost accounting and take your time to build massively, it might work.
In the real world, as soon as you let the unsupervised "free market" build these things, you'll have every corner cut and end up with toothpick st
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Sounds like you live in the ElCheapo version there.
Re: No thanks (Score:1)
In the People's Republic of Quebec, housing construction is unsupervised. As a buyer you look at the plans and you have to understand that no one gives a fuck what the plan says.
Re:No thanks (Score:5, Interesting)
Are you talking about mass timber or just traditional wood construction? Mass timber commonly involves thick beams of cross-laminated timber (CLT) forming entire walls, not just a wooden frame "skeleton".
I live in a newly built CLT house. It's only one story (though tall), but it's in an intensely windy location, which gets hit by hurricane-force storms usually multiple times per year, and where one year I had a storm with cat-5 strength gusts lift up and toss around a steel shipping crate (full of steel beams, timber, cast iron stove, glass, etc etc) like it was a child's toy (it's now anchored in place with boulders). The house is like concrete. Doesn't budge a bit, or even creak, in the strongest winds. You could drive a truck into it and the truck would get wrecked, not the house. My main concerns in the wind are the windows (either blowout, shattering from impact, or - commonly - being sandblasted by debris). The walls are going nowhere.
Here's a picture [naturallywood.com] of such a building going up (not mine) (and another [rezult-timber.com], and another [katus.eu]). All the wood that you see is solid all the way through to the thickness you see. Zoom in on the edge of those panels and look at the number of laminations. Each layer is oriented 90 to the previous layer, making use of the highly orientation-dependent strength of wood to give it strength on all axes. It's immensely strong. Remember also that breaking strength rises with thickness squared, and resistance to bending proportional to thickness cubed (which is why I-beams are shaped as they are).
The pieces arrive precut on flatbeds, are hoisted into place by a crane, and are attached together by frequent zigzagging bolts; assembly can be done in as little as a few days. I did the finishing on my own house; the main challenge (apart from a few bolts that penetrated through and had to be cut off and then filled as best I could) was that while the panels fit together amazingly well for prefab, generally under a centimeter, and sometimes just a millimeter or so off... that still means a huge amount of planing and sanding work to hide the seams, and there's a seam every meter or so on every wall and the roof. And then after that there was a LOT of wood to seal ;) And a lot of gaps to fill (sometimes sizable ones at the sealing), and bolts to hide. But the effect is lovely. Because it's real wood, not like particle board or something. One thing I actually found kind of touching was, the wood was so fresh, that there were some spots where it exuded little droplets of resin - felt like a personal connection to the trees themselves, and I left the resin droplets as a reminder.
There is of course no drywall and the walls are not hollow, so it does change how you have to build. In my place, it means that the wiring and plumbing is in the foundation and outside the walls (but under the insulation and roof cladding). I'm not sure what the typical approach for multistory houses is. For certain things like sinks and showers they had to put a groove in the wall for the pipes (but this was then hidden by tiling or fixtures). On the upside, everywhere is "a stud"; you can anchor huge amounts of weight anywhere you want on the walls and ceilings.
The wood has such a high mass to surface area ratio, and such a thickness, that it's not very flammable. It's still wood, and can still burn, but isn't prone to very aggressive fire spread, with panels usually being rated for 30, 60, or 90 minute exposures, and (unlike steel) remains structurally stable at high temperatures (its damage is through ablation). The outside chars and then insulates the thick interior. With traditional wood framing, beams have
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** at the ceiling.
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I want to be clear, I don't think mass timber is some sort of universal replacement for steel. You're not going to be building 100 story CLT skyscrapers. But it's a pretty impressive new product (it was only introduced in the 1990s, which is a blink of an eye in the famously change-resistant construction industry), and its usage is spreading pretty quickly. For good reason, IMHO.
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I live in a three story wood frame building and the cheapness and lightness of this structure worries me daily. The whole building rattles when the outside door closes. My dishes clink together when people go up stairs. You can hear everything.
That's called "living in the projects".
Re: No thanks (Score:2)
but one woodpecker (Score:3)
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The Japanese have been building large wodden structures for centuries, in an area prone to large earthquakes. They are actually more durable as the ability to move helps them survive the shaking. A lot of of them don't even use nails.
Fire (Score:1)
Wood has a teensy problem as a building material - it burns. Sure, you can inject it full of fire retardent but given long enough t'll still catch light. If its a 2 or 3 story building not a problem, you'll be able to get out in time. In a skyscraper? I'd rather not take my chances thanks.
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See the above [slashdot.org] about CLT (last paragraph).
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Steel and concrete lose strength in fire, too. The Twin Towers didn't come down on 9/11 because airplanes smacked into them; they fell because the ensuing fires weakening the steel. The Grenfell tower in London - made of concrete - was a veritable death trap when it burned in 2017 [wikipedia.org]. Some materials handle fire better than others; but that's no guarantee - proper design counts for a lot more.
If you had bothered to actually read the article, you
Nice gimmick, but very ambiguous. (Score:2)
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The Stave Church at Urnes is still on its original structural beams from the 12th century, and even contains some wooden elements fro the earlier church that stood before it. Ground beams, sills, corner posts, wall planks, aisle wall plates, roof, and various other elements are all original. The exterior cladding has certainly had to be maintained, but thick wood, properly protected, can last ages.
This is unlike most modern concrete, which contains a veritable time bomb. CO2 steadily soaks into the concret
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I don't have the specialty knowledge to speak on any of those numbers. One thing though: It was my understanding that CO2 leaks from concrete, not in
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As we all know, nobody tests construction materials and building designs for fire safety standards before approving them, right?
*eyeroll*
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14 floors? Pffft! Amsterdam did 20+ (Score:1)
This energy-positive timber-hybrid tower will strengthen community in an under-construction Amsterdam neighbourhood [mvrdv.com]
In Amsterdam, a wooden residential tower by MVRDV and Space Encounters [domusweb.it]
The two firms join forces to design a tower of 22 stories featuring a wooden structure and a positive energy balance.
https://hautamsterdam.nl/en/ [hautamsterdam.nl]
I would so paint the last 3 floors red (Score:1)
Giant match!
14 Stories (Score:3)
Is 14 stories really a skyscraper?
Re: 14 Stories (Score:2)
Concrete is renewable, though (Score:2)
Its laid out ever so succinctly here :
https://youtu.be/tTJVbSEIqzE