"in the old-world timber beam there may be lurking some treacherous knot

January 17, 2015 12:32 PM

Michael Green, a Canadian architect responsible for the Wood Innovation and Design Centre at UNBC presents The Case For Tall Wood Buildings [PDF]. He also gave a TED Talk: Why We Should Build Wooden Skyscrapers (transcript)

The Softwood Lumber Board's website rethink Wood has more information on Mass Timber, including a Survey Report on International Tall Wood Buildings [PDF] and information on materials like cross-laminated timber (CLT), structural glue laminated timber (glulam) and structural composite lumber(SCL). The APA-Engineerd Wood Association also has a lot of information. What Is Cross-Laminated Timber?

With wooden skyscrapers, are we Barking up the right tree? The USDA Announce[ed] Support for Innovative, Sustainable Wood Building Materials to Protect Environment and Create Jobs via Gizmodo and The Oregonian. Perhaps the cities of the future will be made from wood. But are Are Wooden Skyscrapers Really Fire Safe? Fire Protection Engineering talks about High-Rise Timber Buildings and the National Fire Protection Association produced the report "Fire Safety Challenges of Tall Wood Buildings".

Charles Kelley, president of the B.C. Ready Mixed Concrete Association, writes Why the Wood Innovation and Design Centre is neither good policy nor good government

Many more links from good magazine.

title from wittgenstein’s radiator and le corbusier’s treacherous knot.

posted by the man of twists and turns (62 comments total)

.. a perversion of the public procurement process.. an affront to citizens.. a tale of unbridled hubris, reckless partisanship, and politics over good governance, and the offensive arrogance of entitlement and power. -- Charles Kelley, president of the B.C. Ready Mixed Concrete Association

The concrete guy is really pissed.
posted by stbalbach at 1:32 PM on January 17, 2015 [15 favorites]

Well, if someone as impartial and informed on wood construction as Mr. Kelley is against it, who am I to not fall obediently in line with my corporate overlords?
posted by IAmBroom at 1:39 PM on January 17, 2015

In my mind I envision cities full of Tudor-style skyscrapers.
posted by Greg_Ace at 1:45 PM on January 17, 2015 [7 favorites]

Wood is also good for large buildings like this one.
posted by Brian B. at 1:47 PM on January 17, 2015

Harvest the wood by stripping some bit of hillside or wood lot bare using enormous petroleum burning machines. Then dry it in kilns, mill it into layers, combine it with a stew of chemicals to get your fancy modern engineered lumber and build your skyscraper out of "wood". Then in 30-50 years when the building is ready to be torn down and replaced with a newer grander structure figure out what the hell you will do with the "wood" you used. Should there be a fire, you will expose everyone around to a toxic cloud of all these chemicals.

Or you could build your building with steel and glass. Materials which are easy to recycle, naturally fire proof and non-toxic.
posted by humanfont at 1:49 PM on January 17, 2015 [21 favorites]

Well, to be fair, I'd also describe the BC government's track record over the last 14 years as "an affront to citizens...a tale of unbridled hubris, reckless partisanship, and politics over good governance, and the offensive arrogance of entitlement and power," but I suspect Charles Kelley's reasons for such disgust are different from mine.
posted by hurdy gurdy girl at 1:52 PM on January 17, 2015 [4 favorites]

Did I just scroll down that PDF and see:

TA
LL
WO
OD

...?

Are we sure this isn't just really expensive penis trolling?
posted by clawsoon at 1:55 PM on January 17, 2015 [3 favorites]

A lobbyist for an association that makes the least-sustainable building material, objecting to new changes based on "not enough study" and changes to the local codes that he doesn't claim are unsafe, just that a two month study period was insufficient time to do ... something. I don't know what and he doesn't really say.
posted by 1adam12 at 1:55 PM on January 17, 2015

Or you could build your building with steel...non-toxic...

Heh, good one.
posted by one_bean at 2:03 PM on January 17, 2015 [1 favorite]

Madison park board signs off on using Tenney Park [ash] trees for grocery store

Madison faces removal of up to 10,000 ash trees due to the emerald ash borer infestation spreading into southern Wisconsin. A wood recycling company will use 20 trees harvested from the park as structural elements in a grocery store going into a vacated commercial site nearby.
posted by dhartung at 2:04 PM on January 17, 2015

Madison faces removal of up to 10,000 ash trees due to the emerald ash borer infestation spreading into southern Wisconsin. A wood recycling company will use 20 trees harvested from the park as structural elements in a grocery store going into a vacated commercial site nearby.

Only 9,980 to go!

I care a lot less about what building material is used (though engineered wood is one of the prettier options, and at least in the pacific northwest can be sustainably harvested) than I do about our not mandating that buildings be designed and constructed for much longer functional lives. Instead we get a lot of cheaply built and poorly designed buildings that don't make any economic sense to adapt or renovate, so they get torn down; at that point it matters little how "green" some of the structural materials supposedly are.
posted by Dip Flash at 2:23 PM on January 17, 2015 [7 favorites]

I am only for this if the final product appears to be made from Lincoln Logs.
posted by Tell Me No Lies at 2:35 PM on January 17, 2015 [2 favorites]

>>>.. a perversion of the public procurement process.. an affront to citizens.. a tale of unbridled hubris, reckless partisanship, and politics over good governance, and the offensive arrogance of entitlement and power. -- Charles Kelley, president of the B.C. Ready Mixed Concrete Association

The concrete guy is really pissed.

I used to work in government in economic development. I have been to Prince George many many many times. I'm not sure if the concrete guy has a right to be pissed or not, but his statements are essentially correct: this is politics pure and simple.

Canada is in some ways a mercantile economy. The hinterlands are regarded as a place to extract raw materials. The resource cycle means that every few years regional economies, like in Prince George, go bust.

In this case the US housing meltdown in 2008 or so left a ton of inventory on the US housing market, and so the market for lumber and other building materials (I suppose a nominally manufactured product) vanished.

This left PG and other "Interior" communities in dire straights, so there was a real push to sell wood.

I remember being at an annual Northern Economic Summit, probably in January 2009. I was out in the lobby and then-premier Gordon Campbell was outside with his security detail, waiting to go on stage and talk to the conference attendees. Despite his pretty wooden public persona, in this quasi-private situation Campbell was animated, peppy. He was holding court with his entourage, saying "I know I know, when I go up on stage I gotta talk about wood. Wood! Wood! Wood! Wood!"

His government poured a ton of money into the technology, and rewrote the building codes.

PG is kind of a funny town. It tries so very hard, but as a service centre it attracts flotsam and jetsam from all over the Interior, kind of a mini-big city. This makes the downtown pretty unpleasant, and half of the downtown is (at least when I was there last) basically abandoned as business owners have fled out to the exurbs on the other side of the hill from the university.

So this new building hopefully will do something to breathe life into the grim downtown.

I did enjoy visiting PG because I had a lot of friendly business contacts and collaborators up there, and it was also "fun" to experience -30 temperatures, although I will take +10C in January here in Victoria any day of the week.
posted by Nevin at 2:41 PM on January 17, 2015 [9 favorites]

"I know I know, when I go up on stage I gotta talk about wood. Wood! Wood! Wood! Wood!"

This would have made an awesome Vine or dance remix.
posted by mandolin conspiracy at 3:11 PM on January 17, 2015 [2 favorites]

Note that trees have a negative carbon intensity when compared to other building materials.
posted by Brian B. at 3:25 PM on January 17, 2015

The concrete guy is really pissed.

His stance can't do anything but harden.

But I've got a serious question here, which I'm combing through the links for an answer to: on the one hand, things like this seem driven by the timber industry. On preview, alot of the material seems like industry lobbying/hey our product is great!

From an urban planning perspective, people are talking about how this will drive more mid-rise development. That's the reasoning behind a recent change to the building code where I live, anyway.

I'm curious to know whether mid-rise wood frame buildings are ill-advised or not strictly from a fire-safety perspective. I know you can treat and fire-rate all of the different kinds of laminated wood products, but it seems to be that reinforced concrete just would be safer.
posted by mandolin conspiracy at 3:35 PM on January 17, 2015

Well, I think they're going to have a hard time arguing this after the massive Da Vinci fire here in Los Angeles. The woodframe construction was said to be "like kindling" by firefighters and damaged many of the highrise buildings surrounding it (photos here), forcing many businesses to relocate. And the fire is likely to increase insurance rates for under construction wood buildings.
posted by rednikki at 3:53 PM on January 17, 2015

Brian B.: Note that trees have a negative carbon intensity when compared to other building materials.

Not to harp on something that everyone else has already pointed out, but: That's only true until they burn down.
posted by clawsoon at 4:02 PM on January 17, 2015

Not to harp on something that everyone else has already pointed out, but: That's only true until they burn down.

Very few burn down. Also, earthquakes are the main risk in some areas, where wood has an advantage over other materials. Wood in forests can be assumed to burn far more frequently.
posted by Brian B. at 4:15 PM on January 17, 2015 [2 favorites]

The carbon argument is really persuasive. It takes a lot of fossil fuel to make steel and portland cement, and the amount you use to harvest wood and make adhesive is trivial by comparison. And the specific technique of using large engineered panels uses mostly young growth wood, so it's not raping the few remaining ecosystems that haven't already been raped to get big timbers.
posted by localroger at 4:31 PM on January 17, 2015 [1 favorite]

Very few burn down.

That's because we've mostly eliminated wood-frame construction from high density areas. When the vast majority of wood structures are widely separated suburban homes, fires are easily isolated and contained.

When dense cities are made of wood, on the other hand, they inevitably and repeatedly burn down. That's why when you're talking about "City X's Great Fire", you usually have to specify the year. Are you talking about New York's Great Fire of 1776, 1835, or 1845?

Wood in forests can be assumed to burn far more frequently.

That's a fair point.
posted by clawsoon at 4:47 PM on January 17, 2015 [2 favorites]

Concrete and steel buildings on fire. The point being that buildings are full of flammable stuff.
posted by Brian B. at 4:52 PM on January 17, 2015 [3 favorites]

Concrete and steel buildings on fire. The point being that buildings are full of flammable stuff.

That's also a fair point. However, note that "no steel frame structure has ever collapsed due to fire," and none of the fires seems to have spread to other buildings. Neither of those things would be true of wooden skyscrapers.

Not saying that I don't love tall buildings made from wood, though. Just not wooden skyscrapers downtown instead of steel.
posted by clawsoon at 5:37 PM on January 17, 2015

However, note that "no steel frame structure has ever collapsed due to fire,"

That's a debunked 9/11 conspiracy theory. Regardless, building height is restricted in most cases due to other reasons, and wood may be suitable for most larger buildings today.
posted by Brian B. at 5:53 PM on January 17, 2015

That's a debunked 9/11 conspiracy theory.

According to the engineer who designed them, the Twin Towers wouldn't have collapsed if there had only been a fire. They were designed to withstand a fire, or a plane impact, but not both. So I'd suggest that 9/11 is a useful case to consider, but not a perfect counter-example.

Also, I'm not familiar with the incident in the video you link to, and I suspect I'm missing something, but I can't see any collapse happening. Does the part of the building that's obscured by smoke collapse?

And I'll admit that I may be having a knee-jerk response, but it seems like a fire that takes over multiple floors of a large steel structure would be closer to a 1 in 10 chance of collapse, while the same fire in a tall wooden structure would be closer to 9 in 10. Is that a ridiculous assumption?
posted by clawsoon at 6:12 PM on January 17, 2015

The point being that buildings are full of flammable stuff.

I guess what I'm getting at is at what point would a high-rise wooden structure actually start fuelling the fire with the material that the structure is made of. Steel frame structures can collapse, sure, but their structure isn't more potential fuel.

There's the issue of fire suppression (sprinklers, etc), fire-stopping at penetration points for services (like plumbing, electrical, HVAC) that's appropriate to the structure materials, and all of that.

On of the interesting things is the use of timber-concrete composites (page 109) as flooring. So, win-win?

But anyway, are we also talking about differences between local fire and building codes and how they'd accommodate more/higher wood structures?

Also thinking about acoustic/noise transfer issues and in residential development, for example. I know that some EU building codes are very strict around things like this, whereas most of the provincial building codes in Canada have a fairly low threshold for that kind of thing.
posted by mandolin conspiracy at 6:12 PM on January 17, 2015 [1 favorite]

So I'd suggest that 9/11 is a useful case to consider, but not a perfect counter-example.

Preface: I think 9/11 conspiracy theories are b.s.

But I think the thing there is that the WTC towers weren't concrete and steel in the way we mean - they were built with a steel truss structure where the exterior walls were held in by the way they were tied into the core, or some such. Consequently, when a lot of that trussing was sheared away by the places, and then you had the heat applied to it as well, it was a catastrophic failure. Someone with architecture/engineering chops can correct me if I'm wrong.
posted by mandolin conspiracy at 6:18 PM on January 17, 2015 [1 favorite]

Does the part of the building that's obscured by smoke collapse?

At 48 seconds the top floors crumble.
posted by Brian B. at 6:27 PM on January 17, 2015

The carbon impact study only looked at transportation costs and if you read it you will not that the authors choose the lowest co2 option when calculating journeys. For example the kiln drying process itself is extremely carbon intensive. Also the study is not looking at the engineered lumber as proposed for building skyscrapers. This material has a number of additional carbon intensive inputs required in manufacturing the glues and other non wood bits. Once all this is factored in the amount of co2 that is sequestered in a longstanding building is only 15% of the tree's carbon. however if you let the mature tree remain standing during that time it would continue to pull more carbon out year after year effectively storing more co2 after only a couple years. So actually cutting a tree down and putting in a house is much worse than just leaving it be if you want to reduce co2. Timber and concrete end up much closer in terms of their co2 intensity. Meanwhile steel framed construction is 1/4 the carbon intensity of timber framing.
posted by humanfont at 6:28 PM on January 17, 2015 [3 favorites]

At 48 seconds the top floors crumble.

Ah, thanks.
posted by clawsoon at 6:30 PM on January 17, 2015

On of the interesting things is the use of timber-concrete composites (page 109) as flooring. So, win-win?

That may be pictured here. Also related.
posted by Brian B. at 6:32 PM on January 17, 2015 [1 favorite]

The carbon impact study only looked at transportation costs and if you read it you will not that the authors choose the lowest co2 option when calculating journeys.

Not the one I linked. It calculated embodied energy in three types of structures, with transportation factors: "Embodied energy is the energy used during the ‘cradle to gate’ lifecycle of the material (extraction and manufacturing/processing)" (from footnote on page 3). This isn't surprising since steel and concrete use massive amounts of heat to produce, around 1400 C for concrete, and over 1600 C for steel. Kiln drying of wood is done at temperatures as low as 120 degrees F.

So actually cutting a tree down and putting in a house is much worse than just leaving it be if you want to reduce co2.

A wooden building presumes that one didn't use a worse alternative, and wood is deemed sustainable for buildings because its growth cycle is less than the building's life cycle generally.
posted by Brian B. at 7:29 PM on January 17, 2015 [2 favorites]

Wooden skyscrapers: The only way to make Canada more Candian
posted by vorpal bunny at 7:48 PM on January 17, 2015 [2 favorites]

What about bamboo? Bamboo (unless I'm mistaken) seems easily renewable, has wood-like qualities.
posted by el io at 7:52 PM on January 17, 2015

Candian - that's a thing.
posted by vorpal bunny at 7:55 PM on January 17, 2015 [2 favorites]

Regarding the fire issue, the type of construction typically associated with tall (5+ stories) wood buildings these days is cross-laminated timber construction (CLT, multiple links above) not light wood framing (Da Vinci, most houses in North America for the last century or so).

CLT construction is closer to concrete construction than conventional light wood framing, as floors and walls are essentially monolithic masses, not framed assemblies. This also makes it super quiet.

Like heavy timber beams, CLT slabs have a substantial fire rating. In a fire they develop a thick charred layer that protects the core. A 2x6 just goes poof.
posted by Casimir at 8:11 PM on January 17, 2015 [3 favorites]

I did enjoy visiting PG because I had a lot of friendly business contacts and collaborators up there, and it was also "fun" to experience -30 temperatures, although I will take +10C in January here in Victoria any day of the week.

I am so sick of how people on the west coast seem to think that having milder temps makes you superior to the rest of the country.

It was +10 in Calgary yesterday and the day before, and unlike the nonstop rain you have in Victoria, we had blue skies in the sunniest winter city in Canada.

We also are the third most diverse city in Canada with the highest rate of international immigration of any major city in North America in 2012 and 2013- ANY city, including Toronto, Vancouver, SF, NYC, Miami, LA, etc etc etc etc. So yeah, I'll take that over the trickle of immigrants and the white monoculture in Victoria.

Oh, we're getting six-storey wood condos here, now.
posted by ethnomethodologist at 8:23 PM on January 17, 2015 [2 favorites]

We also are the third most diverse city in Canada with the highest rate of international immigration of any major city in North America in 2012 and 2013- ANY city, including Toronto, Vancouver, SF, NYC, Miami, LA, etc etc etc etc. So yeah, I'll take that over the trickle of immigrants and the white monoculture in Victoria.

Uh, I don't think anybody was attacking Calgary. Chill. Despite the Chinook.

Anyhoo, thanks Casimir. That interesting. As I've done some more digging into the FPP links, there are some interesting illustrated examples of pyrolysis and timber. Seeing now what CLT means in terms of fire rating and performance.

And back to my original question, the building code in Ontario has only been modified to allow six-storey wood structures. We're not talking skyscrapers here.
posted by mandolin conspiracy at 8:51 PM on January 17, 2015 [1 favorite]

The wood goes in the 120c kiln for weeks, while the steel is heated to 1600c for minutes. The wood kilns are often run with wood, because mills have a lot of sawdust, bark and scrap wood. Burning wood emits more CO2 than pretty much any other fuel source. The timber industry PR folks are working hard, but once you look at the raw data it becomes fairly obvious that it is very far from carbon neutral or negative carbon that they claim.
posted by humanfont at 9:59 PM on January 17, 2015

The timber industry PR folks are working hard,

Probably not as hard as the coal industry, since coal is not only mined, but pollutes more and creates mountains of unusable ash. I'll leave it to Wikipedia to declare which material requires less embodied energy as it relates to a glulam beam since that is the wood product closest to the construction technology we are discussing.
posted by Brian B. at 10:47 PM on January 17, 2015

Reinforced or 3D-printed concrete vs wood for moderate-sized structures is not an all-or-nothing proposition. In places with an indigenous wood-construction tradition, local wood supplies, manufacturing ability and the right climate or seismic situation, engineered wood (or perhaps bamboo - although I recall reading somewhere bamboo cultivation is more water- and land-intensive than wood per usable structural quantity) is going to be preferred. Other places it might be pre-fab, foamed, poured, or 3D-printed concrete.
We can even mix concrete, metal and wood in one structure! Wait, that's what we're all ready doing.

Living in the treed, wood-crafted, seismically active PNW, I'd like to see more tall wooden buildings.
posted by Dreidl at 3:36 AM on January 18, 2015 [1 favorite]

I wonder how the carbon emissions of fibreglass would compare as a building material.
posted by clawsoon at 4:59 AM on January 18, 2015

Burning wood emits more CO2 than pretty much any other fuel source.

Yeah, but it's CO2 recently pulled from the atmosphere, so it's climate neutral.

OK, so I don't have actual numbers, but the idea that timber might be worse than steel and concrete from a climate change/CO2 perspective seems absurd. Forestry is just not energy intensive enough to be on the same scale as something like concrete manufacturing.
posted by ryanrs at 5:10 AM on January 18, 2015

Carbon emmisions for Steel vs Timber framing compared
posted by humanfont at 5:38 AM on January 18, 2015

Also we are not replanting the forests at the same rate we are cutting them down. We are losing more than 50,000 square miles each year.
posted by humanfont at 5:47 AM on January 18, 2015

It seems fairly irrational to believe steel is better than wood from a CO2 perspective, but humanfont's link shows the devils in the details. Only 15% of a forest ends up as a wood product the rest is wasted. Is that true? I don't know. Seems crazy. There might be some assumptions in that study that are not applicable to the FPP such as the use of trees 20 years old not 200, not clearcutting old growth but responsible management of new growth.

What about bamboo?

That's actually a really good solution which the majority of the planet uses all the time in construction (see Asia). It's a grass, very fast growing. Not sure about bamboo skyscraper why not.
posted by stbalbach at 7:36 AM on January 18, 2015

It was +10 in Calgary yesterday and the day before, and unlike the nonstop rain you have in Victoria, we had blue skies in the sunniest winter city in Canada.

Don't Chinooks cause depression? Anyway, Victoria gets half as much rain as Vancouver. I met a guy who moved out here from Saskatchewan the other day because it's warmer here.

We also are the third most diverse city in Canada with the highest rate of international immigration of any major city in North America in 2012 and 2013- ANY city, including Toronto, Vancouver, SF, NYC, Miami, LA, etc etc etc etc. So yeah, I'll take that over the trickle of immigrants and the white monoculture in Victoria.

Whoa, buddy, I was talking about the weather which I think is fair game for a playful discussion. I didn't make any claims about ethnicity, which I think is a little over the line. Anyway, as my son's school in Fernwood will show you, Victoria is anything but a monoculture. And my wife is from Japan...

Anyway, it's really interesting to hear how Calgary is so similar to Miami. I hadn't heard that before!
posted by Nevin at 7:38 AM on January 18, 2015 [1 favorite]

Carbon emmisions for Steel vs Timber framing compared

Oh my. The author, a steel industry guest contributor, seems to reverse himself at the bottom, and links to a pro-wood study and a glulam beam maker's site which unequivocally state that wood is better for construction. Quote from the apparent author:

JR: I do think that, as with all life-cycle analyses, different assumptions can lead to different conclusions. If one could be confident of sustainably harvesting wood, that would change the equation, as one recent study found. Of course, one might ask, shouldn’t sustainably harvested wood be compared to recycled steel. Systems impacts are also complex. So I’m very open to people coming to different conclusions depending on the choices they make. I generally trust the choices that the US Green Building Council’s LEED certification makes and recommend you do so also when constructing a building. They apparently are tough on wood, especially wood that isn’t certified by the Forest Stewardship Council. I will pursue this further.

His mistake was not only to blind us with science, but he simply assumed, but did not show, that cut wood is giving back its carbon at a faster rate than can be grown again. No credit is even given for the carbon sequestered because, citing the Kyoto protocol no less, it is assumed to be replacing another wood product in decay. It was already assumed, however, that steel and concrete were being compared.

Also we are not replanting the forests at the same rate we are cutting them down. We are losing more than 50,000 square miles each year.

Other products such as paper aren't material to the construction assessment. Switching to steel because paper and cardboard is also made from trees is a convenient fallacy guiding so many perhaps.
posted by Brian B. at 7:55 AM on January 18, 2015 [1 favorite]

Humanfront, the article you linked doesn't address the issue of fossil fuel CO2 vs. biofuel CO2. It just treats all CO2 emission as equal, which seems misleading when considering long term climate change.

That article also does sneaky stuff like ignoring the wood used in roofing: "Since plywood roof sheathing is assumed to be identical for each house, this material was not included in the emissions calculations."

The article then goes on to compare the ratio of CO2 emission for the different buildings, minus the roof timber CO2. But leaving out the fixed CO2 amounts from the roofing exaggerates the ratio. You can't subtract large fixed values then compare the results as ratios.
posted by ryanrs at 8:00 AM on January 18, 2015 [2 favorites]

The total co2 added to the atmosphere is the critical number. Each fuel source contributed a different amount. In terms of the energy output per ton of co2, burning wood generates more than other fuels.
The promise that shifting to biofuels will be neutral form an emmisions perspective ignores the fact that we are burning wood faster than we are making it. We are cutting forests down faster than they are growing back. Some biofuels like ethanol require huge amounts of petroleum to make the fertilizer used to grow them. So you don't save anything.
Non lumber uses for wood are part of the overall demand for wood. If you start harvesting more trees to make CLT, then you end up cutting down more trees because overall demand goes up.

Finally almost all the studies linked above come from the industry association or government agency tasked with promoting steel or wood.
posted by humanfont at 10:24 AM on January 18, 2015 [2 favorites]

Coal, though. Definitely compressing coal faster than we're burning it. Any peer reviewed sources for your claims?
posted by one_bean at 11:27 AM on January 18, 2015

It's "emissions," btw.
posted by one_bean at 11:27 AM on January 18, 2015

Bamboo is an interesting material - the stiffness-to-weight and strength-to-weight ratios are excellent for a biological building material - but it has a couple of limitations. It's more susceptible to rot and fungus than wood, and, being hollow, it burns more quickly. It also doesn't have that little bit of non-elastic "give" that wood and steel have that make screwing and nailing possible. Do either with a piece of bamboo, and all you'll get is a split. Even drilling it is a major challenge. It's also difficult to form, which makes the kind of joinery that you can do with wood (or steel) difficult/impossible.

Some of this may be solved with engineered bamboo boards. It's difficult to say how much of its excellent raw stiffness and strength will be lost in that case, though.

I haven't been able to find any tall (400ft+) structures built of bamboo, other than bamboo scaffolding that was supported by the building it was built around. Its stiffness-to-weight ratio is at least as good as wood, steel, stone, concrete and brick, so its critical height should be as high, too, making tall bamboo structures theoretically possible. I'm guessing it's the problems of joining bamboo that have so far defeated any such attempts.
posted by clawsoon at 6:59 PM on January 18, 2015

They use bamboo as construction scaffolding in Asia.
posted by Brian B. at 7:17 PM on January 18, 2015

Tangentially related, I keep turning over the word "glulam."

Glulam. Glulam.

It's kind of gluey on the tongue.
posted by mandolin conspiracy at 7:29 PM on January 18, 2015

It’s often claimed that biomass is a “low carbon” or “carbon neutral” fuel, meaning that carbon emitted by biomass burning won’t contribute to climate change. But in fact, biomass burning power plants emit 150% the CO2 of coal, and 300 – 400% the CO2 of natural gas, per unit energy produced.

From a report by The Partnership for Public Integrity
posted by humanfont at 7:29 PM on January 18, 2015

That's not peer-reviewed, and is about the use of waste from timber harvesting, not the use of wood as a construction material.
posted by one_bean at 9:33 AM on January 19, 2015

But in fact, biomass burning power plants emit 150% the CO2 of coal, and 300 – 400% the CO2 of natural gas, per unit energy produced.

Yeah but.. so? It's like a pool filled with water. If you scoop water out, then pour it back in, the net effect is zero. But if you add water that wasn't there before, the pool will overflow. Such is the problem of fossil fuels vs. wood.
posted by stbalbach at 10:34 AM on January 19, 2015 [1 favorite]

clawsoon: It also doesn't have that little bit of non-elastic "give" that wood and steel have that make screwing and nailing possible. Do either with a piece of bamboo, and all you'll get is a split. Even drilling it is a major challenge.

Thanks for that comment. Something I intuitively knew - we build a fence every year at a two-week campsite with bamboo - but couldn't put into words before.

We hold the fenceposts up by piledriving a spud bar into the ground, which is conveniently just a bit bigger than our bamboo (grown in a campmember's yard!), then pound the dirt in around the base to firm it up. If it were wood, we'd drive it directly in - or at least be able to push it an inch or two deeper when needed. But since it's bamboo, it has to come out, and the spud bar goes back in, repeat...
posted by IAmBroom at 2:14 PM on January 19, 2015

We are not replacing 1 for 1 though. You cut down a mature tree and replace it with a sappling which is like taking a cup of water out of the bucket and putting back in a teaspoon. It will be ten or more years to recover the capacity of that tree in terms of co2 removed per year. Furthermore the overall amount of forest is shrinking, we are not even keeping a 1 to 1 ratio of cups to teaspoons. The idea that we should embrace cutting down more trees seems like a terrible idea.
posted by humanfont at 10:47 PM on January 19, 2015

You cut down a mature tree and replace it with a sappling which is like taking a cup of water out of the bucket and putting back in a teaspoon.

It's more like taking a cup of water out of a bucket and putting it in another bucket for storage, to allow the other bucket to fill again. Don't take my word for it though:

http://www.washington.edu/news/2011/07/13/wood-products-part-of-winning-carbon-emissions-equation-researchers-say/
posted by Brian B. at 5:38 AM on January 20, 2015 [1 favorite]

The old-tree-vs-new-tree issue is complicated. Big old trees keep sequestering more carbon every year.

In one old-growth forest plot in the western United States, for instance, trees larger than 100 centimetres in diameter comprised just 6% of trees, but accounted for 33% of the growth.

However, they also reduce the number of trees that can grow in a given area, so if you look at "the overall carbon stored in a plot", constantly farmed young trees may be better than old trees.

My impression is that, so far as carbon sequestration goes, clearcut is worst, old growth is much better, and tree farms may be best. Although... given the energy-intensive ways we've figured out to promote growth in every other type of farming we've done, tree farming may not remain best for long.
posted by clawsoon at 6:04 AM on January 20, 2015