wooden skyscrapers
October 20, 2016 9:41 PM   Subscribe

New techniques mean that wood can now be used for much taller buildings - "Wood has many attractions as a construction material, apart from its aesthetic qualities. A wooden building is about a quarter of the weight of an equivalent reinforced-concrete structure, which means foundations can be smaller. Timber is a sustainable material and a natural 'sink' for CO2... Using wood could reduce their carbon footprint by 60-75%, according to some studies. There are two main concerns about using wood to build high. The first is whether wood is strong enough... the second worry: fire."
posted by kliuless (30 comments total) 9 users marked this as a favorite
 
Previously
posted by the man of twists and turns at 10:34 PM on October 20, 2016 [1 favorite]


The last link goes to a metafilter post about Churchill, nothing about wood skyscrapers.
posted by octothorpe at 3:31 AM on October 21, 2016


Fire is my main concern. How are they going to address that?
posted by oceanjesse at 4:55 AM on October 21, 2016


Forget fire.

Earlier this week, there was a very large gas explosion in Portland. The explosion happened somewhere between a 3-story wooden building and a 5-story concrete apartment building.

The concrete building was heavily damaged, but is still standing. By contrast, there is nothing left of the wooden building. (Amazingly, nobody died)
posted by schmod at 5:48 AM on October 21, 2016


You should hear this story I know about three little pigs who built skyscrapers.
posted by XMLicious at 6:22 AM on October 21, 2016 [5 favorites]


Wood, Jerry! Wood.
posted by stevil at 6:46 AM on October 21, 2016 [2 favorites]


I assume they handle earthquakes OK.
posted by ZeusHumms at 7:32 AM on October 21, 2016


Fire is my main concern. How are they going to address that?

Article mentions covering wood with a thin layer of concrete, which provides fireproofing and sound dampening. Areas where the floor is supported by pillars receives extra concrete. In the test described in the article, it exceeded expected loads.
posted by ZeusHumms at 7:41 AM on October 21, 2016 [1 favorite]


Fire sprinklers should take care of fires.
posted by My Dad at 8:11 AM on October 21, 2016


Well you can only have so many years in a row where our number one export to China is scrap steel before you need engineers to come up with solutions like this. Fires, earthquakes, termites, and longevity are serious concerns here but there are experts to worry about these things. And then there are people like us worrying about those experts... I guess when you have a society that repeatedly makes massive long-term blunders for an immediate payoff (see U.S. economic policy) it's pretty healthy to be skeptical of something so challenging to common sense as a skyscraper with wooden girding. In the 90s I remember hearing scary stories about China building very tall buildings with bamboo frames. That was before we swapped our middle class for slightly cheaper doodads and gadgets.
posted by Locobot at 8:33 AM on October 21, 2016


There's also the risk of fire during the construction phase.

In my city a local developer fudged the building code rules and built a 144 unit, five story student housing apartment complex using wood construction (officially the building is four stories tall because the ground floor is slightly below grade).

As construction progressed locals started calling it "the Tinderbox". Then it actually caught fire.

There was a mass evacuation of the area and a dramatic helicopter rescue of the crane operator who was trapped above the flames. One hundred and twenty people were evacuated from their homes and dozens were made homeless or were unable to return to their homes for months. A two-block evacuation zone remained around the site for five days because of the threat of the fire damaged crane collapsing. The crane operator spent several months in hospital recovering from burns to his legs, buttocks and right hand and announced he would be retiring from his profession.

The developers were eventually fined $74,000 by the Ministry of Labour, but the cause and origin of the fire were never determined. The apartment complex was rebuilt using the same design, despite local protest.
posted by Secret Sparrow at 9:07 AM on October 21, 2016 [5 favorites]


My major worry would be the impact that a higher demand for wood would have on deforestation and illegal logging. The long, large beams that would be needed to support a wooden structure could only come from mature trees. If a developer can get their materials slightly cheaper, no one's going to ask too many questions about the swathes of forest that were clear-cut.
posted by Pallas Athena at 9:23 AM on October 21, 2016


Not necessarily true, Pallas Athena. Many fast-growing temperate softwoods make excellent beams, and you can do some really amazing things with engineered wood these days as well. I've never heard of a modern building with hardwood framing, in fact; it's all done with conifers. Hardwoods are typically used only for finish materials like trim, decking, flooring, etc rather than as structural material.
posted by Anticipation Of A New Lover's Arrival, The at 9:55 AM on October 21, 2016 [4 favorites]


Why would the beams need to come from one piece of wood? They can now make beams out of smaller pieces of wood laminated together (glulam). Similarly, I know it is pretty common for floor joists here (Ontario) to be made of plywood sandwiched between two 2x2s.
posted by any portmanteau in a storm at 9:55 AM on October 21, 2016


Wood apartment buildings up to about seven stories seem pretty common around here lately. So far there haven't been any fires but I'd still be pretty leery about living in one.
posted by octothorpe at 9:55 AM on October 21, 2016


I was going to say if they're going to use wood, they would definitely be using engineered wood, which is pretty amazing stuff.

I'm rebuilding an old car and have almost finished making the wood body. Wood is a pretty amazing material.
posted by maxwelton at 10:00 AM on October 21, 2016 [1 favorite]


any portmanteau in a storm is pretty much right on. Even in typical residential construction, if you want to span an opening in a load-bearing wall that's wider than about five feet, you're going to do it with an LVL. Structural beams of all shapes and sizes are made from Glulams. Large ceilings like you might find above a garage or a great room are typically made with I-joists nowadays rather than two-by stock. These are all engineered wood products that are made from pretty shitty wood, with excellent performance characteristics.
posted by Anticipation Of A New Lover's Arrival, The at 10:02 AM on October 21, 2016 [1 favorite]


maxewelton, that's awesome; do you have pictures?
posted by Anticipation Of A New Lover's Arrival, The at 10:05 AM on October 21, 2016


I've gotta admit, the prototype looks great.
posted by non canadian guy at 10:47 AM on October 21, 2016


On a recent trip to Finland (Helsinki suburbs, Espoo, etc.), I was struck by the amount of wood framing being used in road construction (bridges and overpasses). I'm no expert in construction techniques, but I've driven past a lot of road construction sites in the US, and my untrained eye in Finland was like, Wow that's a lot of wood! Can anyone comment on these kinds of structures and whether the use of wood is different in various countries?
posted by Tandem Affinity at 10:50 AM on October 21, 2016


One of my favorite ongoing mental experiments is to imagine what the world would be like if people were smaller. Like, what if we were a quarter the size we currently are but everything else was the same?

It never occurred to me before now, but one consequence might be that we would use a lot more wood in construction. If we were 1:4 scale, buildings wouldn't need to be as tall and therefore we could get away with using materials with lower strength:weight ratios much more easily than we can in real life. Also, since the buildings would be smaller, they wouldn't take up as many trees as a full-sized building does for a given number of occupants.

(One of the big benefits of shrinking people is that we would use fewer per-capita resources in general.)
posted by Anticipation Of A New Lover's Arrival, The at 11:18 AM on October 21, 2016


Timber is a sustainable material and a natural 'sink' for CO2..

Not when it is in buildings!!!!
posted by Burn_IT at 1:12 PM on October 21, 2016 [1 favorite]


Secret Sparrow: "There's also the risk of fire during the construction phase. "

This is a weirdly sweep under the rug risk. Here in BC we just recently relaxed restrictions on wood building heights extending them to 6 stories from 4. People are taking advantage of course but still I don't see much in the way of mitigation for fires after they start. It would seem to be a simple thing to supply at least partial temporary fire suppression in the same way as we supply temp power.

I'm envisioning a tree at the nearest hydrant(s); Hoses to areas of the building hooked to some sort of large scale omni directional sprinkler. Have it be manually operated so that some worker knocking a head off doesn't flood the whole building. Leave it in place until the permanent sprinklers are installed or at least until the wood structure is covered with the planned fireproofing.
posted by Mitheral at 1:30 PM on October 21, 2016


I wonder if they've investigated sound/vibration permeability between different parts of the building.

The apartment I'm renting is an unit on the top floor of a 3 story wood-frame and the noise transmissibility is frightful, not to mention that there are 5 heavy duty HVAC units bolted onto the wood roof - which is definitely not rated for such things. It's like living in the body of a guitar, only there isn't a sound hole for the vibrations to come out.
posted by porpoise at 2:14 PM on October 21, 2016


porpoise: "I wonder if they've investigated sound/vibration permeability between different parts of the building"

This is a pure attention to detail; a wood frame building, especially with a fire suppressing layer of concrete, can be as quiet as a concrete building. However it is maybe easier to have a poorly detailed wood frame building that still functions abet a noisy one vs the same with concrete where poor detailing in construction leads to catastrophic pour failures.
posted by Mitheral at 3:23 PM on October 21, 2016 [1 favorite]


Um, yes when it is in buildings?

Wood is mostly made from carbon taken from the air, and when you cut some down and turn it into a building you can grow more (and we do, prodigiously) so it's definitely renewable and potentially sustainable as well, if carefully managed, which it is within our reach to do as long as we can have sensible policies. As construction materials go, it's the most easily renewable one we have (unless you want to include dirt, I guess).

Buildings are also a great place to put wood if you want it to be a carbon sink. Trees only function as carbon sinks if their wood is removed from the carbon cycle after they die rather than being allowed to decompose and re-enter the system. Building stuff out of it helps to do that, because we tend to protect buildings and prevent them from doing things like rotting or catching fire, and when the buildings reach the end of their service lives the wood can be either recycled or buried (as in a landfill, though more elegant disposal paradigms should be developed) either of which helps prevent the carbon from getting back into the atmosphere.

That's not to say that there aren't significant environmental issues with the use of wood for building construction—there are—but it's certainly a renewable resource and it certainly functions as a carbon sink. I don't really see why that would even be in question.
posted by Anticipation Of A New Lover's Arrival, The at 7:03 PM on October 21, 2016 [1 favorite]


You know, if we could figure out a way to make buildings that are on fire all the time anyways, flammability in the building materials wouldn't be a problem. I, uh, can't think of any way that would work, but just trying to think outside the box. Because the box is on fire.
posted by XMLicious at 7:26 PM on October 21, 2016 [1 favorite]


I don't really see why that would even be in question.

I'm with Burn_IT on this. Living trees are busy inhaling C02 and exhaling oxygen. Dead trees are not. We're currently low on trees -- we don't have an excess of them sitting around decomposing on forest floors and returning their carbon to the cycle, because we've harvested the fuckers.

The article goes on to state that ferro-concrete construction is more productive of carbon waste, but after they spit out a whopper like that, I'm not inclined to take this at face value.
posted by oheso at 2:05 AM on October 22, 2016


I'm not sure what you mean by carbon waste? Concrete production generates a huge amount of CO2. And when you start looking at embodied energy the steel it is reinforced with is even worse. Wood in general is much better though I imagine that the specialty composite products featured in the article are going to have higher carbon emissions and embodied energy than a 2x material.
posted by Mitheral at 11:20 AM on October 22, 2016 [2 favorites]


Um, the reason we don't have an excess of trees sitting around on the forest floor is because they decompose and return their carbon to the cycle. Most construction timber is farm grown, and more of it could be. Living trees are busy inhaling CO2, absolutely, but on the scale of a forest the amount of trapped carbon dioxide is pretty static because there's not really room in a mature forest for additional biomass—as climax communities, mature forests are by definition maxxed out in terms of how much life the land can support.

On a tree farm, you grow the trees (locking up carbon) and then take them away and grow more trees (locking up more carbon) and on and on for as long as you like, given careful management of the land. As long as the harvested wood isn't allowed to burn or decompose, you can keep sucking carbon out of the air and locking it away. Wood farming is a carbon-negative industry, it just is. The problem is land use change, because tree farms, being monocultures, don't have the same ecological value as the ecosystems that they replace. That is a real issue, but it's different from carbon pollution.

And concrete production is massively carbon-producing. Again, this is not in question. Both the chemical processes involved in making the cement and the fuel burned to cook it during manufacture generate huge amounts of carbon dioxide. The cement and concrete industry gets its own category in a lot of carbon dioxide source breakdowns, because it's big enough that it's worth dealing with as one of the major pieces of the climate change puzzle.

This is really well-studied, settled-science type stuff. Truly.
posted by Anticipation Of A New Lover's Arrival, The at 6:29 PM on October 22, 2016 [2 favorites]


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