The Case for Making Cities Out of Wood

http://nautil.us/blog/-the-case-for-making-cities-out-of-wood

by cjg • 8 years ago

79 101 8 years ago

avoidwork• 8 years ago

Some cities were wood, and they burned. My concrete condo is in the burn path of the 'great Ottawa fire'. Wikipedia doesn't have enough pictures, worth googling.

https://en.wikipedia.org/wiki/1900_Hull–Ottawa_fire

bryanrasmussen• 8 years ago

I'm wondering if 'total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres.' means that stuff isn't going to burn until you get temperatures where steel melts anyway?

farrisbris• 8 years ago

It would seem so. from the article:

Massive wood walls and structural beams and columns comprised of engineered panels have demonstrated fire performance equal to concrete and, in some cases, superior to steel

peterwwillis3• 8 years ago

Tons of major cities have been wiped out from fire in the early 1900's. But you have to consider how ill-equipped they were to handle fire, not to mention a total lack of research. Modern cities have working fire hydrants and buildings can have multiple fire suppression systems. Most of this is due to those massive fires happening.

Here is NIST's report on fire resistance of timber structures (https://www.nist.gov/sites/default/files/documents/el/fire_r...). It includes guidelines that help increase the fire safety of wood buildings. This page (https://www.firechief.com/2017/03/14/are-wood-frame-high-ris...) shows CLT has had testing to approve it for use in 6+ storey buildings in multiple countries.

fredley• 8 years ago

The case against:

https://en.wikipedia.org/wiki/List_of_town_and_city_fires

xigency2• 8 years ago

I think of Chicago first. The wood city that burned and led to the invention of 'skyscrapers'.

nervousvarun• 8 years ago

The focus of this article is innovation in this space.

What happened in Ottawa or Chicago or Tokyo is relevant in a historical sense but this is about recent innovations that make wood viable (both from a safety/fire-resistant perspective and economical).

bigpicture• 8 years ago

Chicago has a CLT building - the new flagship McDonald's restaurant is CLT and steel.

Additionally, a CLT office building has been approved in Chicago and will be the largest CLT building in the United States when finished.

vvillena• 8 years ago

The kind of wood used here does not burn like normal timber. Its treatment gives it strength and fire resistance. There are some large scale tests that need to be done yet, in order to better understand how a fire would behave in a midsized wood building. It's all in the article.

Keep in mind, this is way more testing than usual, lots of other materials have been used in large buildings, sometimes with disastrous consequences (see: Grenfell Tower fire).

bl4ckm0r3• 8 years ago

Emperor Nero likes this element!

golergka• 8 years ago

Three out of three top comments here are about fires - an issue the article specifically talks about.

How about reading the whole piece instead of just a headline?

senorjazz2• 8 years ago

How about reading the whole piece instead of just a headline?

Sacrilege! People don't have to read the article to have an opinion. This is the internet.

dsfyu404ed• 8 years ago

The article does not address the topic in sufficient detail which is why people keep commenting about it.

xigency2• 8 years ago

He wants to do many more experiments because it’s still not clear how, in mass timber buildings, to get compartment fires to reliably burn out on their own, a “cornerstone of fire safety engineering design,” he writes.

In this context, the article's later comparison of this wood to concrete seems exaggerated.

netcan• 8 years ago

For the people saying "fire!"...

Wood went out of fashion because of urban fires, resource (natural forest) depletion and long term maintenance (rot, termites..) issues.

Modern engineered timber (according to proponents) solves these problems. It's engineered from renewable crops of fast growing timber, is resistant to fire and pests... Proponents claim it is now suitable for skyscrapers but certainly for 5-15 story urban residential buildings.

Imo.. what is missing are clear advantages, a reason to bother. I don't think there's much cost advantage at this point. Weight savings.. maybe there are some applications where this is important. Generally, it's a bit of a solution searching for a problem.

Fricken2• 8 years ago

There is also, alongside the environmental and economic, an aesthetic-psychological case for wood cities. Clare Farrow, who is co-curating a current London exhibit called “Timber Rising–Vertical Visions for the Cities of Tomorrow,” wrote in Dezeen, Studies are showing that the presence, scent and touch of wood can have remarkably positive effects, not only on people’s wellbeing in a general sense, but more specifically on stress levels, blood pressure, communication, learning and healing.” A 2015 review in Wood Science and Technology supports her claims and also suggests that “specific aspects of wood such as colour, quantity, and grain pattern should be examined"

Of course, I don't need a study to tell me that wood is nice.

asdfasgasdgasdg• 8 years ago

You probably shouldn't be smelling or touching the wood frame of your home. If you do, there is a bad problem with your drywall.

kijin• 8 years ago

You can easily achieve the same effect by adding wood panels to visible parts of the interior. No need to build the entire thing with wood.

simtel20• 8 years ago

I recall talk recently about a shortage of sand appropriate for creating cement. It seems that this compressed wood turns that potential shortage into an opportunity.

jessaustin6• 8 years ago

Talk of sand shortages anywhere but in extremely remote and non-sandy locations is ridiculous. Sand is among the cheapest materials on earth. If it ever became difficult to procure, the price would rise.

Retra• 8 years ago

Plenty of sand in the Sahara, last I checked.

awkward4• 8 years ago

Using wood for building is a carbon sequestering process. Compare it to using cement, a process that massively releases carbon.

jessaustin6• 8 years ago

This is great; another way for warming enthusiasts to put their money where their mouths are. We should see new wooden cities just as soon as they sell their properties in Manhattan and Miami...

user3359• 8 years ago

This is more of a problem with time frames. Wooden houses last 100-200 years if very well built. I've seen teardowns after 50, sometimes less. What's the environmental cost of building 4 wood buildings to last as long as 1 concrete building?

Concrete construction lasts centuries. And if torn down, can be crushed and after separated from rebar, re-used as aggregate in another project.

fulafel2• 8 years ago

What about surviving fires without structural weakening? An average apartment building has to endure many fires over its lifetime.

(Maybe it's a nonproblem and you can replace the damaged wood easily, or the fires don't typically do permanent damage, i don't know.)

leetcrew• 8 years ago

as a layman, i assume that our wood techniques are not yet at the level where you can use it for twin tower scale buildings, but this raises an interesting question for me anyway. if such a building had all its structural elements made of wood, would it be likely to suffer the same catastrophic weakening in the event of a 767 strike?

nusq• 8 years ago

Actually timber has a nice property of loosing strength gradually and slowly in case of fire, giving time for people to escape. Steel and concrete reinforced structures tend to collapse when a certain temperature is reached.

senorjazz2• 8 years ago

Generally, it's a bit of a solution searching for a problem.

err, the little something called the environment?

roel_v• 8 years ago

Modern wood for building storied buildings is not like 'wood' people think about when they hear the word. It's a laminated material, the strenght of which very much depend on cutting edge expoxy technology. I don't know how environmentally friendly it is, but this is not a log cabin we're talking about.

jaclaz• 8 years ago

Yep, and it's not like "modern" glues/resins have been proved to last for centuries and/or be totally harmless for the humans living in the houses.

Think of formaldehyde based glues (widely used):

https://en.wikipedia.org/wiki/Urea-formaldehyde

https://en.wikipedia.org/wiki/Urea-formaldehyde#Health_conce...

Tharkun3• 8 years ago

Imo.. what is missing are clear advantages, a reason to bother.

There are quite a few actual advantages. Speed of construction is one. The ability to prefabricate large elements (like entire walls) off site is another. In some areas of the world there's a lot of cheap excess timber after some kind of pest (I'm thinking a beetle?) killed entire forests. It insulates really well out of the box, especially when it comes to noise insulation. Wooden buildings are more earthquake resistant than stone/concrete.

There's also quite a number of disadvantages with concrete. Lack of sand. Implication climate change. Requires rebar reinforcements which ups the price and turns the whole thing into a giant radiator.

CLT is a pretty awesome building material, really.

escape_goat3• 8 years ago

In some areas of the world there's a lot of cheap excess timber after some kind of pest (I'm thinking a beetle?) killed entire forests.

Dead wood isn't even useful as firewood. You can't just pick dead trees up off the forest floor and saw them up into lumber. Even if you could, no government would let you transport that timber out of the immediate vicinity in which it was found, due to the aforementioned pest.

Perhaps there is a surplus of cheap excess timber in some areas of the world, but there isn't much chance of that having anything to do with any kind of pest.

Yaggo• 8 years ago

There's also quite a number of disadvantages with concrete. Lack of sand.

This is good point. One would think that sand is unlimited supply, but that's actually not the case:

https://www.businessinsider.com/world-running-out-sand-resou...

toast0• 8 years ago

The ability to prefabricate large elements (like entire walls) off site is another.

You can do that with concrete as well [1], it's often called precast concrete. concrete wall sections are heavier than wood wall sections, so you do need larger equipment, and tend to have smaller pieces.

[1] https://en.wikipedia.org/wiki/Precast_concrete

nerdponx2• 8 years ago

Who knows, maybe the sand shortage will get severe, driving concrete prices up to the point where people start looking for alternatives.

bliblah• 8 years ago

How about natural disasters such as hurricanes in the east, earthquakes in the west and flooding elsewhere?

I'm not a structural engineer so I would like to know if there are some possibilities here that I may not be seeing.

peterwwillis3• 8 years ago

Pick a building material, you can construct it with modern methods to resist natural disaster. Even wooden homes can resist hurricanes and earthquakes now. The biggest concern for wood is still fire, but we have much better ways to manage it and make the wood fire-resistant.

tangue• 8 years ago

Imo.. what is missing are clear advantages, a reason to bother.

Sand depletion [0], recyclability

[0] https://www.smithsonianmag.com/science-nature/world-facing-g...

repolfx• 8 years ago

A lot of people are saying sand shortage, but surely weight savings matter more? If your building is 6x lighter your foundations can presumably be a lot cheaper?

logfromblammo• 8 years ago

In that case, you should be comparing engineered wood with concrete that includes basalt fiber composite rebar [0] and weight-cutting aggregates like expanded polystyrene beads [1] and loose (basalt|carbon|glass) fiber. In small-building construction, a no-steel concrete wall could be just 2 inches thick where steel-concrete building code might mandate minimum 8 inches just to prevent swelling rebar from destroying the wall from the inside. Also, basalt rebar is trivially bendable, so curved shells can add strength from geometry where straight steel rebar would be limited to using rollers to bend every bar to the correct curvature or to use doubly ruled surfaces like one-sheet hyperboloids and hyperbolic parabolas. And more non-sand aggregate means sand shortage has less impact, right?

There are a lot of ways to save weight on buildings, but not all of them translate well to building codes that can be used by building contractors without having a staff engineer on site to determine whether the equations work out to acceptable structural strength or not. And all the building codes out there for wood are going to be for standard dimension lumber, and not specific types of engineered wood. Until the codes are updated, the building inspector will look at your cross-laminated composite wood beams, look them up in his book, and tell you that your plans don't conform to code.

Not to mention that once your houses are light enough to blow away in a strong wind, now you need to anchor them to the ground with cables and hooks, and wind forces and the stresses at the anchor points become a whole new engineering problem.

Cities aren't going to be made of "wood". They'll have to be made of ANSI/ISO-standard-X-conformant structural members and ANSI/ISO-standard-Y-conformant processes. We'll get there. Slowly.

[0] https://en.wikipedia.org/wiki/Basalt_fiber

[1] https://en.wikipedia.org/wiki/Expanded_polystyrene_concrete

briffle• 8 years ago

When wood burns (at least CLT Beams) it has a much longer time until failure than steel. When steel gets hot, it quickly loses its structural strength, and can collapse.

tomrod• 8 years ago

A recent advance in wood technology should interest the neighborhood’s developers: Teng Li, a University of Maryland mechanical engineer, created with his colleagues wood that’s as “strong as steel, but six times lighter,” he said. Liangbing Hu, Li’s co-author on the study, added, “This kind of wood could be used in cars, airplanes, buildings—any application where steel is used.” Making it is just a two-step process. The scientists first boiled natural wood in a mixture of sodium hydroxide and sodium sulfite, to remove some of the lignin and hemicellulose, substances contained in the walls of wood cells (the former retard parasite and bacterial attacks, the latter cover and bind fibers). Then they put the wood in a hot press, which leads, as they say in the paper, “to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres.” The result, they conclude, is a “low-cost, high-performance, lightweight alternative” to “most structural metals and alloys.”

If this decreases the burn rate, as other commenters have pointed out, and the input energy is manageable, then this has a chance. Cool!

perl4ever3• 8 years ago

The obvious question, to me, is whether this process can be used to produce a uniform enough product to be highly reliable.

lifeisstillgood2• 8 years ago

If you can extrude or shape the densified wood, into something "branch-like" but at steel like strength then you open up new building opportunities - our cities are dominated by straight lines, for good reasons, but branchlike handrails, footpaths and arches open up a lot of possibilities for good architects to chnage the look of a city beyond the mere material it is made of

ctack• 8 years ago

There is a compression step in wood preparation life cycle. You could replace this step with shaped moulds to create these features. Or maybe it's cheaper and easier to 3D route out of bigger masses.

lifeisstillgood2• 8 years ago

just wondering how much pressure it takes to compress wood to destroy the cellular structure. One might suspect more than enough to crack a mould that had lovely curvy shapes in it ...

chriswarbo• 8 years ago

Teng Li, a University of Maryland mechanical engineer, created with his colleagues wood that’s as “strong as steel, but six times lighter,” he said

Phrases like this make me uneasy. "Strength", especially when used informally like this, is quite ambiguous (e.g. there's a reason we don't make buildings out of spider silk).

Overall it's quite an uplifting piece though, and I would certainly like to see such a revival.

m0llusk• 8 years ago

First of all, what they are talking about is more like paper made out of wood since the fibers are treated extensively and then formed. Secondly, large and spreading structure fires which have such a devastating history have been essentially eliminated by use of sprinkler systems.

vinayms• 8 years ago

Even if the technology is perfected and proven superior on several counts, the adoption has to overcome the psychological barrier. The places that don't have a culture of wooden buildings, especially the floor, will need some convincing.

As an Indian, I don't encounter wooden floor often. Modern buildings are all brick and reinforced concrete, and old temples are stone mostly. Any wooden floor one might come across are just wood panels installed on concrete floor. Nearly two decades back, the city library (Seshadri library, Bengaluru) was renovated, and as a part of it the shelves were raised and a wooden corridor was installed to enable access to higher shelves; its a tall building with a dome and a large hall under it, your typical library. Needless to say, I was quite apprehensive to walk on it, so were most people there. Apart from that, the only experience I have is standing on my desk to change the bulb. The desk is quite sturdy - the bulkier carpenter stood on it to demonstrate - but I just can't trust it the same way I trust concrete floor. When on a wooden surface, I step softly, hoping to make myself lighter, just in case, though I know its nonsense.

crooked-v• 8 years ago

With the mention of temples, it's actually pretty common for historical temples, churches, and castles to have wooden rooms for anything past the ground floor, since it was much, much easier to build a few main structural supports out of stone and then fill in the rest with wood later.

Of course, I'm a little biased on the subject, living in a 100-year-old all-wooden building (you can see the huge beams resting on the foundation in the basement) that I chose for earthquake resistance. I'm actually a lot more comfortable knowing that the whole building can sway while all the parts stay attached, compared to the many old brick buildings around here that will literally fall apart if an earthquake happens.

pseudolus• 8 years ago

There are actually plans to build a 350 meter (approx. 1050 foot) skyscraper in Japan. https://www.dezeen.com/2018/02/19/sumitomo-forestry-w350-wor...

For those interested in more "concrete" expressions of the existing capabilities of timber based construction an 18 story dormitory was assembled in 70 days at the University of British Columbia.

https://news.ubc.ca/2016/09/15/structure-of-ubcs-tall-wood-b...

Here's a time-lapse: https://www.youtube.com/watch?v=GHtdnY_gnmE

chasedehan• 8 years ago

The question I have about all of this is the environmental impact of the "densification of wood." They cite it being similar to paper manufacturing, which is really energy intensive and is a horribly polluting industry.

I don't have any info on the above, but it is something I wonder about.

specialist• 8 years ago

I'm day dreaming about 'aktivhaus' (sp?) style residential in the desert.

What would that look like?

My starting notion is a three level structure. Bottom is carport, patio, storage. Middle would be kitchen, baths, common areas, study. Upper would be bedroom(s). Maybe a roof top deck.

South wall would have horizontal solar louvres. Kinda like the Burr library in downtown Phoenix.

Roof top solar something. But I'd still want to be able to look up at the stars.

Grey water system of some sort. So the ground level would have a cistern of some sort.

Is wood a viable option for the desert? I know zilch about thermal loads, insulation, etc. If so, how much wood?

The Case for Making Cities Out of Wood

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