Timber Towers Are On the Rise in France (citylab.com) 202
A reader shares a report: Spurred by concerns over climate change and the negative impacts of concrete manufacturing, architects and developers in France are increasingly turning to wood for their office towers and apartment complexes. Concrete was praised through much of the 20th century for its flexibility, functionality, and relative affordability. In France, the material ushered in an era of bold modernist architecture including housing by Auguste Perret and Le Corbusier. Today, however, wood is lauded for its smaller environmental footprint and the speed with which buildings can be assembled. "Wood had largely disappeared and was seen as a quaint material," says Steven Ware, a partner at the architecture firm Art & Build, whose latest wooden office building opened in Paris's 13th arrondissement earlier this summer. "[But] the energy it takes to put a concrete building up, to run it, and then dismantle it when it becomes obsolete was too much. Using mass timber in office buildings seemed like something we had to do." The production of cement, one of the main ingredients in concrete, generates an estimated 5 percent of the world's carbon emissions. Trees, in contrast, capture CO2, helping offset emissions produced by a typical building process. And then there's the string of other construction advantages that make wood economically appealing. It's lighter, which means digging smaller foundations in the ground. Crane costs come down, as they're no longer hauling blocks of cement hundreds of feet in the air. Driving a nail into a slab of wood requires a lot less energy than driving one into concrete. Months can be knocked off the construction timeline.
Fire anyone? (Score:4, Insightful)
Sounds like a good way to have a towering inferno. The stuff we put inside large buildings burns quite readily. But the fire generally stops in a single room. But if you suddenly make everything out of wood, what's to stop the fire from spreading everywhere?
Re:Fire anyone? (Score:5, Funny)
They'll coat all the wood in a protective layer of concrete.
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Yeah, I read up on it and you are pretty much right - they rely on gypsum. But this engineered wood also is naturally fire resistant because of the way it chars, apparently. I haven't found a lot of detail but it seems like the cross laminated timber [greenspec.co.uk] that they use has a pretty good fire rating.
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A city made of wood leads to things like the Great Chicago Fire https://en.wikipedia.org/wiki/... [wikipedia.org]
Plus, with the recent building fire in London, you would think it would be fresh on their minds. http://money.cnn.com/2017/06/2... [cnn.com]
Re:Fire anyone? (Score:5, Informative)
Actually the Grenfell Tower fire was a combination of flawed materials, flawed installation technique and improper physical plant (for firefighting)..
Instead of ripping out interior walls and redoing insulation that way, they clad the exterior of the building in insulation panels.
Which, all things considered, is a great way of air-sealing and insulating an existing building.
It's just that the panels used weren't properly fire rated. And the panels were installed in a way (leaving a gap between the original exterior and the paneling, meant to facilitate drying in wet conditions) that made the new skin of the building function like a chimney/flue.
Also, the original building had an inadequate fire suppression system. No building-wide alarm. No sprinkler system. Trash dumped all over the building. Dangerous proximity of boilers and gas pipes.
Basically this was a fuckup waiting to happen.
Re:Fire anyone? (Score:5, Insightful)
But if you suddenly make everything out of wood, what's to stop the fire from spreading everywhere?
First, as stated in the article the wood panels are engineered lumber that is very thick. There is very little surface area to the wood used, compared to like what people use in a fireplace or backyard bonfire, so the wood will not burn quickly if the char layer that develops doesn't stop the fire completely.
Second, most every building code I've seen will require a fire resistant layer around structural components. In most houses this is done with sheets of drywall over the wood studs in the wall. Typically 1/2 inch on walls and thicker on ceilings.
My brother was an architect and I remember the topic of the fire rating of doors coming up. Wood doors are actually quite durable in a fire, and those certified as a fire rated door will have a little metal badge on it giving it's fire rating. The goal of a fire rating is not necessarily the survival of the building but the survival of the occupants. So long as the building holds up long enough for people to get out in a fire then it's considered safe for people. A quick Google search tells me a wood fire door will be fire rated for 20 minutes, I assume the thick wood floors that they are using will hold up for much longer.
Remember, these fire ratings are tests under direct exposure to a fire before the door is not considered a barrier to the spread of fire. It's not like the whole building will come down 20 minutes after a fire starts. If a building is large enough, or contains flammable materials, then it's likely to have sprinklers.
In other words, I think they have this figured out.
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Some good points, but there is a difference between a door's fire rating and the fire resistance of a structure. Biggest issues is what happens when it fails.
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Due to sprinkler systems and/or prompt firefighting response... Not because the slab is concrete. (The walls only very rarely concrete.)
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The walls only very rarely concrete. ...
In USA
In Europe they are.
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The wood they are using is generally thick heavy laminated structures that are fairly well inherently protected; this isn't assembling 2x4's on the 10th floor (or for that matter placing TJI joists). Most will have gypsum [board] supplemental fire protection, not to mention fire sprinklers, and columns will be heavily protected.
With thick structures, you char the wood, you don't burn through it. This provides a supplemental level of protection. You also don't have the temperature driven deflection issues
Cubes in Pole Barns (Score:3)
There's no reason we can't just stack IT people in cubes in pole barns. Fortunately, nobody with any talent actually needs to work in a crappy office, so most companies are smart enough not to try this.
Recent 10 story Portland OR timber tower (Score:5, Informative)
Recently, as in this week, they completed a low-emission earthquake-resistant timber tower in Portland, Oregon.
Fire risks tend to come from inefficient fire suppression systems and lack of coatings. Or inadequate emergency exits. As we've seen from London, England, concrete towers clad in flammable plastic are more of a fire trap than wood timber buildings are. It really depends on the full architectural design.
Re: Recent 10 story Portland OR timber tower (Score:2)
No matter what, and and amount of fire retardant thrown on wood, wood can't be 100% fireproof. Modern CLT highrises are tragedies waiting to happen.
Wood is fuel, concrete is not
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"As we've seen from London, England, concrete towers clad in flammable plastic are more of a fire trap than wood timber buildings are."
I missed the wood tower catching on fire offering that comparison. When did that happen?
During WW I and WW II when cities burnt.
Sorry you've been on another planet.
Cross Laminated Timber or CLT (Score:3)
CLT and mass timber is the shit. They are also working on LVL veneer based types that are like super plywood vs. the current finger jointed lumber version You trade material cost for labor but you can have a house framed in a day. Also concrete is a carbon emitter for a long time. It is not prone to fire. You can have them CAD CAM all the windows, doors, conduit, and plumbing into the walls at the factory, and it is renewable.
Addressing Some of the Objections Here (Score:5, Interesting)
Wood can be grown and harvested sustainably on tree farms where generation after generation of trees selected for structural properties and rapid growth are cultivated. Any such "green" inspired building program should/would ensure that all the timber used comes from such sources. And so yes, building permanent structures out of wood does lock up CO2 as long as the structures stand - whereas CO2 released in the production of concrete is in the air for centuries.
The actual material used for framing a structure has nothing to do with the fire safety (or lack of same) in an inhabited structure. Metal and concrete framed structures are no safer on that count than wood. The fire hazard that threatens life is entirely due to the furnishings and utilities inside the structure. By the time a frame of wood frame building starts to burn the interior is already destroyed, and the inhabitants have either escaped or are dead. Note that modern construction techniques using fire proof gypsum board that isolates the structure from the interior (gypsum does not burn and actually absorbs energy as it decomposes).
Wood is a pretty remarkable material. It is in fact an advanced composite material produced by natural nano-factories. It compares favorably with far more expensive synthetic composites, and beats them all in cost. Used properly (taking advantage of the anisotropic properties of wood beams) a good wood beam comes with a factor of 3 in stiffness/weight ratio of the best performance ofunidirectional carbon fiber epoxy composite, and beats structural steel. Sitka spruce is used in the upper stage of Trident II SLBM missile since it had the best properties for the role, over all other candidates.
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Of course not. ... facepalm.
That is why one of the most advanced nation on the planet is building them.
It is a hoax, obviously
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not quite right, how about some experts?
https://www.nist.gov/sites/def... [nist.gov]
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Perusing the document, it seems to support exactly what I said. I specifically mentioned the fire encapsulation requirement that is used in modern wood frame structures citing gypsum board (though other solutions exist.
Re:Addressing Some of the Objections Here (Score:5, Interesting)
That was quite some detail in that report. I read parts and skimmed the rest. It basicaly concludes; Tests/sudies done showing large timber structures to have comparible safety, but have concerns with earth quake/fire combo, but with a 2hr fire resist seam fine with. Also a lack of large of full scale tests.
All in all, it looks positive for large timber use, they just want more data and better refinement of requirements for the building code and such.
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Sitka spruce is used in the upper stage of Trident II SLBM missile
It is nice to know that our nuclear arsenal is based on renewable and sustainable carbon sources. That certainly makes me feel better about vaporizing our adversaries.
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Again this supports exactly what I said. It was not the structure of Grenfell Tower that burned. It was a decorative outside "furnishing" added to the building.
Nails?! (Score:2)
Nails suck. Use screws.
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Wood-framed houses (common in NA).
Termite stocks (Score:2)
I'm buying termite-related stocks
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You're thinking wood frame - i.e. mostly air. Try visiting a building with 6" thick solid wood walls - it's a completely different beast.
This Just Makes No Sense (Score:2)
The "Insulated Concrete Forms" construction of concrete housing was what I was aspiring to if I ever built a house. Probably won't, unless a tornado knocks this one down, but the advantages were that the ICF house is highly insulated, almost in the class of superinsulated, and it takes a really big tornado to knock it down. What's "inefficient" about that? I don't even live in "tornado alley" any more, but had a "tornado aloft" take down my ham antenna and turn one mighty oak into a very distracted loo
le feu de joie (Score:2)
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Increasingly common due to cost (Score:3)
I've seen a lot of this in my area, generally what they call podium construction, where you have a 1 to 3 stories of concrete construction and then build wood frame up to the maximum height allowed, typically 5 stories of wood. As TFA outlines, it is cheap and very fast compared to all concrete, and has become a go-to for mid rise residential. Unfortunately, it makes it possible to cut corners to an even greater degree when it comes to flooring, and fire safety is entirely dependent on active suppression. I have actually seen one of these buildings survive a fire during construction (with a great effort by the fire department), but afterwards it was demolished back down to the podium.
In the end it comes down to labor cost, concrete is surprisingly labor intensive and labor costs are a huge part of construction in first world countries. I've seen some beautiful concrete work done in South America that would be impossible in the US simply because of labor costs - Imagine a 20 story concrete facade entirely finished by hand: Beautiful, but impossible to do in the states.
Driving a nail (Score:2)
Driving a nail into a slab of wood requires a lot less energy than driving one into concrete
Seems like a desperate attempt at coming up with advantages... Does the energy of driving a nail into concrete really have some measurable impact? How many nails are driven into concrete in modern buildings?
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'Wood' has fewer letters than 'Concrete' therefore you save electricity every time you type it. Don't be such a climate change denier / fossil fuel apologist.
Next up - lab-grown wood! (Score:2)
You know it's gonna happen..
Is this for real? (Score:2)
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Wood is a really scarce resource.
In France? Or the rest of north Europe for that matter? Ever checked google earth?
The rest of your comment is rather stupid, as growing wood and dying wood and rotting wood is a zero sum game. It does not affect the CO2 level at all.
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The moron is you.
The story is about FRANCE.
A country in Europe. Not about *deforestation*.
We "farm" trees since centuries. There is no *deforestation* in Europe, stupid idiot.
Source by people who are bad at math... (Score:2)
"wood is lauded for its smaller environmental footprint and the speed with which buildings can be assembled"
This is something only someone very bad at math would say, or someone with a bias or agenda.
I do sustainable logging so you would think my bias is towards wood but I built my house, farm buildings and USDA/State inspectable butcher shop out of concrete.
The reason is that concrete has a far lower carbon footprint, lasts far longer, makes for far more energy efficient buildings and at lower costs. Both
Did we forget the history of San Francisco? (Score:2)
The place was always subject to earthquakes, so during the nineteenth century buildings were made of wood. It was found that New Zealand kauri pine was an ideal material: it was strong enough to build high, grew straight and knot-free for hundreds of feet, and was flexible enough to resist the strongest earthquakes. By the end of the century, the entire city was made of kauri.
Two problems arose. NZ realized that a kauri takes a thousand years to grow, and that their export rate was totally unsustainable. Th
Re:Trading one problem for another (Score:5, Informative)
Lumber supply forests are harvested and replanted these days.
Re: Trading one problem for another (Score:3, Insightful)
Also there is a fair amount of carbon sequestered in the building itself. That's assuming the building doesn't burn, which is why I won't get into a tall wooden structure.
Re: Trading one problem for another (Score:5, Interesting)
Also there is a fair amount of carbon sequestered in the building itself. That's assuming the building doesn't burn, which is why I won't get into a tall wooden structure.
The type of wood buildings they're making nowadays don't burn very easy. (not talking about timber framed houses like the US, but the kind used for taller buildings such as this article). They take wood- cut it in strips, arrange the strips in alternating directions (for added strength) and then glue them together with a fireproof glue.
They're actually more fire-safe than steel buildings. Steel will melt or lose strength with fire (as in 9/11 twin towers)- the modern timber buildings resist fire at higher temperatures than it takes for steel to lose integrity.
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Now I'm not the original guy but I think it's a choice of words here. Some of the newest treated wood ignites at 500C. Now steel won't melt at that temperature, not even close, but at 550C it loses 50% of its strength. So I sort of get where guy is coming from but yeah, it's an iffy argument. However, I think we can all agree that at either temperature, no one is going to exist very long. That said, I'm not sure about France's standards but I would assume that the level of planning that has to go into
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Re: Trading one problem for another (Score:5, Informative)
You don't rate a fire-resistant structure by its ability to sit baking indefinitely at a certain temperature, but by the number of minutes or hours it provides safety while people evacuate and/or extinguish the fire. And once you have a fire-safe structure that doesn't collapse and compromise its egress paths, you worry about fire safety of the building which includes ventilation, fire suppression, and materials to avoid asphyxiating the occupants in a poison gas chamber.
Thick timber chars on the outside when exposed to extreme heat. This is almost a self-healing, temporary insulation to slow the heat transfer to the rest of the wood on the inside of the timber. That's why a big log in your fireplace burns for many hours and doesn't immediately explode your house from over-pressure. The timber continues to be able to bear most of its rated load while this outer surface is burning.
Meanwhile, steel will quickly conduct heat throughout and soften until it suffers a load failure, long before it has reached its liquid phase. The twin towers didn't collapse because the steel was solid one minute and liquid the next. It collapsed because it became soft enough for large horizontal spans to sag and separate from their supports, fall a whole story, and exceed the load-bearing capability of the level below.
Steel structural members have to have fire insulating layers to mitigate this type of problem and allow people to escape. The violence of the plane impacts in the twin towers destroyed egress routes, trapping people. It also tore away a lot of the fire insulation (asbestos) meant to protect structural steel, so the collapse happened sooner than it might have in a typical fire.
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Time between harvests on most "farmed" forests average 25-30 years. Might be some with faster growing tree, but even that is about 15 years.
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consume the original amount of CO2
The CO2 is trapped in the cut down tree. So long as the wood isn't burned or rotting away, the CO2 is sequestered inside the frame of the house or building or whatever. Same goes for if you take a chopped down tree and get it to sink in a body of water. That's a carbon sink quite literally. Anytime you prevent wood from burning or being decomposed, that removes carbon from the atmosphere. Now the act of cutting the wood does release some CO2 gas, not in just the thing that's cutting the wood, but in th
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If you're lucky. In many places they don't bother to replant unless the government forces them to, in which case they complain about excessive regulations hurting their get-rich-quick schemes. Even int he US the timber industry prefers clear cutting as it keeps the expenses low.
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Which is not necessarily a good way to do it. It would act similar to a wildfire, in that for a few years there is bad erosion. It also has the same type of tree in that plot instead of a mix, and so forth. Especially if this is a national forest, loggers should be required to do what's best for the forest, it's not their land after all. Yes, it is much harder to pick just some of the tallest trees and dead trees, because once they've built the logging road into a patch they want to cut it all down to justi
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That's actually not so bad, because you simply plant more trees and the problem takes care of itself.
It's long term carbon release of previously sequestered carbon that's the issue.
Re:Trading one problem for another (Score:4, Interesting)
I recall a prominent global warming alarmist getting kicked out of the group he was in because he advocated the using of wood as a building material, since using wood in this way is an effective carbon sink.
Using wood as a building material only causes deforestation if people don't plant new trees in their place. No one does that since it's not only bad for business, they'd run out of trees, but it's illegal in any place I can think of. If there is a place in the world that allows for clear cutting of trees and not planting new trees in that space then I'll show you a place that lacks any real government.
Using wood for buildings is good for the environment. If you believe that steel and concrete is better then I'll ask you to show me your math. If you believe that we just shouldn't be building new structures then I'll ask you to show me your age. Saying we shouldn't need new office buildings and homes is something that I'd think would come from a child or someone suffering from senility.
If someone knows who that was that advocated using wood as a building material as a carbon sink, and got shunned for it, then I'd appreciate a reply on who that is.
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Don't it Depend on the Tree?
Soft woods like pine grow quick, but the wood is, you know, soft. Wouldn't want to live in a skyscraper made of that!
AFAIK, the hardier the wood, the longer it takes for the tree to grow. That means a long-term investment in your re-planting, and a lot can happen to your plot of re-planted little sprouts (bugs, deer, fires, suburban sprawl, drunk kids on ATV's, massive natural gas deposits) while you wait the lifetime or two for your trees to grow to full size.
Re:Trading one problem for another (Score:5, Informative)
You're on the right track to some of the "devil in the details".
Soft woods like pine grow quick, but the wood is, you know, soft. Wouldn't want to live in a skyscraper made of that!
Calling pine a soft wood, and implying that it wouldn't serve well in a structural sense, is perpetuating a myth. SPFs (spruce, pine, fir) are highly regarded for their structural properties. Douglas fir, Southern Yellow Pine, Sitka Spruce, Hemlock...all have excellent MOE/MOR ratings, while yes, having low Janka Hardness ratings. Along with time-to-yield and price, these structural properties are why SPFs rule the US stick-built construction supply.
AFAIK, the hardier the wood, the longer it takes for the tree to grow. That means a long-term investment in your re-planting, and a lot can happen to your plot of re-planted little sprouts (bugs, deer, fires, suburban sprawl, drunk kids on ATV's, massive natural gas deposits) while you wait the lifetime or two for your trees to grow to full size.
Harder wood trees, do "generally" take longer to grow. However, today's new-growth trees pale in comparison to the mostly gone old-growth trees from a properties comparison. The hardness may be there, but their MOE, MOR, and density are usually lower, and their stability and durability are much more volatile. But, again, those are generalities. The science behind wood is quite fascinating; much more in depth than I imagined when I got into woodworking.
The Wood Database [wood-database.com] is a great resource.
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Just to reinforce dj's point - hardness and strength are two completely different engineering qualities and usually have very little to do with each other. Aluminum for example is both fairly soft (the surface deforms readily in response to concentrated pressure) and fairly strong (in bulk it can withstand fairly impressive compression and tensile pressures)
In addition, hardness does tend to correlate with another, far less attractive quality: brittleness. The more rigid something is, the less it can temp
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I saw a construction project in Hainan that used bamboo and coconut fiber to reinforce concrete. They still used some steel rebar, in addition to a mesh of bamboo. The coconut fiber was dumped into the mixer. According to the foreman, the result was lighter, cheaper, and more resistant to seismic shear. But less resistant to compressive force, so it was only used for buildings of 3 stories or fewer.
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How long can a concrete and steel building last?
How long do even well engineered wooden structures last before succumbing to rot or burning down?
Well... There are wood buildings that are 1,500 years old. A properly taken care of wood building can last a long time. Wood doesn't rot if it is not exposed to water. The secret is proper waterproofing. As for fire, the modern wood buildings use flame retardant glue and are safer than steel at high temperatures.
Wood is also more earthquake resistant because they sway easier. Wood is more resistant to wind damage.
Re: Trading one problem for another (Score:2)
Show me the standing wood building on Barbuda. On the otherhand using concrete and steel one can easily build a building that will withstand a category 5 hurricane unscathed.
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"Wood is more resistant to wind damage."
Tell that to a hurricane or a tornado.
Down in areas where this sort of thing is problematic, consistently, the only houses that generally survive with more than cosmetic damage are concrete structures.
Also, if you're worried about concrete structures being able to move, there are additives which improve can increase a building's ability to sway and withstand cracking.
And, at the same time, there are building techniques for isolating such a structure to minimize sway.
A
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On top of that, there is a class of concrete that actually ABSORBS CO2 of its surroundings.
Yes, there is such a concrete. It is very expensive and no one would ever consider using it in a large project. It will come up once in a while as a show house where people want to demonstrate a "green" future construction. They often look very posh, will claim having a very small (or even negative) carbon footprint, but very little will be said about how much it costs or if there is any study on the building meeting the CO2 output claims.
I had a conversation with a professor that was studying a way to a
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"Yes there is such concrete. It is very expensive..."
So are various high-strength mixes used in high rise construction. And while current processes make it unfeasible outside of academic, experimental testing, there's no guarantee that this will remain that way, as testing is ongoing.
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Sure, all commonly used cements used in concrete will absorb CO2 over time. Perhaps I misunderstood the original claim but the implication I got was that it absorbed more than that was used to create it. The lime in cement will slowly turn to limestone as it absorbs CO2 from the air, but this will be no more CO2 than what was cooked out of it after being mined from limestone.
If people want to get CO2 negative cement that's actually affordable then they should to do as that professor proposed, use nuclear
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And how many "sibiling" structures in the area are the same age.
Sure. If you take extremely good care of a building it'll last a lot longer.
Do you REALLY expect this sort of in-depth care from modern society ON EVERY BUILDING? And do you expect the kind of care in construction from modern "Throw it up FAST!" builders?
I invite you to sample multiple seasons of the television productions of one Canadian by the name of Mike Holmes.
Not saying it CAN'T be done. Simply that concrete is just a superior building
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Not saying it CAN'T be done. Simply that concrete is just a superior building material in terms of ease of use, longevity (the world's oldest concrete structure is sneaking up on its 1900th birthday) and maintenance.
It'd be nice if we hadn't forgotten how to make that kind of cement mix.
My house is over a hundred years old, the concrete foundation is crumbling in places. Other than one corner where some idiots hadn't properly sealed the new porch, the wood frame is doing fine.
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Not saying it CAN'T be done. Simply that concrete is just a superior building material in terms of ease of use, longevity (the world's oldest concrete structure is sneaking up on its 1900th birthday) and maintenance.
It'd be nice if we hadn't forgotten how to make that kind of cement mix. My house is over a hundred years old, the concrete foundation is crumbling in places. Other than one corner where some idiots hadn't properly sealed the new porch, the wood frame is doing fine.
Actually, I hear we recently rediscovered it--and it's basically 'use saltwater.' Sometimes, it's the stupidly simple things... (The salt changes the structure of the concrete, I suspect somebody more interested in concrete can find the article.)
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Actually we know exactly how the Pantheon was built and the type of concrete used.
And yes, we can reproduce it today.
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Not really. Most atmospheric oxygen has marine origins.
What's more you can replant forests, although you lose the ecological benefits if the forest you just cut down was virgin as opposed to managed timberland.
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It would be ironic if you write that from a deforestated suburb!
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Wrong. They 'inhale' CO2 and 'exhale' oxygen during photosynthesis. All photosynthetic organisms do so.
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Wrong. They 'inhale' CO2 and 'exhale' oxygen during photosynthesis. All photosynthetic organisms do so.
Only when the sun is out. Most plants consume O2 and expel CO2 at night.
Nevertheless, trees are a net producer of oxygen (and a very good carbon-capture device) if you don't account for them rotting after they die. But oceans and marine plants are a more important producer of oxygen.
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If you focus only on CO2 and ignore the annoying forest critters and such, then cutting down (and replanting!) trees is good because young growth sucks up more CO2, which you are going to harvest and use in a building indefinitely.
Re:Driving nails? (Score:5, Informative)
Are they really comparing the energy cost of driving a nail?
Wood has a place but IMO if you want a durable structure use reinforced concrete. Maybe this wave of construction is only expected to stand for 30yrs?
My (small) multi-unit in Canada is built with wood timbers and is 218 years old. As long as you keep it dry, wood can be very durable.
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The article says that a huge benefit of wood is that it can be taken down/disassembled much more easily and with less energy than concrete. I believe that's what the OP was referring to when he said "Maybe this wave of construction is only expected to stand for 30yrs?". I don't think he meant to say that wood wasn't durable.
Personally, I still think that wood is a luxury. It may not be a luxury in Canada, but in France, wood is still a lot more difficult to buy than cement and rebar. So I still expect ceme
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Re:Wooden home (Score:4, Interesting)
That's solid wood, however, possibly dense old-growth wood. These are modern composites. I have no idea if that makes them more or less durable over a century.
What it likely makes them is hard to repair, unless the particular composite method they used becomes the dominant one. With a quick skim, I see about 4 competing technologies for pre-engineered, mass-produced wood composites. If you build with one and it falls out of favor, it might be tricky in the future to do any repairs. If nobody is making nail laminated timber and you need to sub in cross laminated timber, what are the ramifications?
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Nobody is questioning the fact that concrete is a good material from a structural and construction standpoint.
But wood, properly maintained, lasts quite a bit longer than 30 years. The oldest wooden building in the world is 1300 years old, a five-story pagoda in the temple complex of Horyuji in Japan.
There's no question concrete is more durable with less maintenance, and people are working on lower carbon-footprint concrete. Switching to non-carbon energy sources for converting limestone to cement would e
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Are you sure that it's burning fuel for firing limestone that emits CO2? Firing limestone is the chemical reaction CaCO3 --> CaO + CO2, after all.
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The thing is, properly built, concrete buildings also cost less to heat and cool.
So, long-term, a well-designed building will offset its initial carbon footprint though energy savings.
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I would be very surprised if concrete - basically solid artificial rock laced with conductive iron rods, were a better insulator than wood, which is naturally full of air voids.
Granted you can add all sorts of things to concrete to improve its insulating properties, but they typically come at the expense of strength and durability.
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Look into "insulated concrete forms".
You get a 6-8 inches of concrete wall with insulation (bound to a structural webbing) 2-4 inches thick (with thicker options available both for concrete AND for insulation).
But the base wall is rated at R-20.
Also, being a monolithic wall, there's are no "hidden" breaks in the air/vapor seal of the building. Just at windows, doors and utility penetrations.
This makes the house far more easier to make airtight. And while mechanical ventilation is required, it requires FAR
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Some good points - one thing though
> a wood frame building will share MOST of the benefits you'd see in a concrete building
Are we sure they're talking wood frame? I haven't investigated this particular one, but most of the "wooden skyscraper" discussions I've heard aren't frames, but laminated wood panels - basically solid wood wall-segments similar to the concrete ones commonly used.
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I'm talking mainly stock lumber framing for housing.
Laminated lumber/panels for anything higher than a couple stories.
Just keep in mind, well engineered laminated wood products are expensive in and of themselves too.
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Laminated panels have very different properties than frame (aka mostly air) construction. It's hardly fair to lump them together.
In fact that's rather the point of the people pushing wooden construction today - they're not talking about wooden *frame* construction - there's good reason that was abandoned. But laminated timbers and panels solve pretty much all of those problems, and especially for tall buildings the strength-to-weight ratio of wood makes it extremely appealing.
Oh, and I looked up some info
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That's just it. ICF (insulated concrete forms) ARE. Think "foam cooler" outside, and another inside.
And the houses are generally so tight that mechanical ventilation is required. So, central air and they hold their temperature well.
Re:Driving nails? (Score:4, Interesting)
The vast majority of CO2 emissions from cement manufacture is not from the energy used to heat the kiln but as a produce of the chemical process itself when limestone (calcium carbonate) is decarbonated into lime (calcium oxide).
This means that it is not enough just to change into using clean energy for heating the kiln.
Luckily, cement could be produced CO2-free using a heated electrolysis process but the process if very new and untested and it would require that the a huge chunk of the cement factory would have to be rebuilt. The world can not wait 20 years for clean cement.
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The HÅryÅ-ji pagoda is 122 feet tall and was built in 594. I'm not sure concrete is more durable.
The Pantheon is 190 feet tall and built in 126. I'm sure concrete is at least as durable.
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Of course concrete burns - even diamond burns.
More relevant to the low temperatures in your average building fire - concrete rapidly cracks and weakens in response to heat, while even without fire resistant treatments wood forms a layer of insulating protective char.
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On top of wood being flammable, termites don't eat concrete ...just saying ...