Shiver me timbers. Architects plan wood skyscraper for resident life

Jun 21, 2013 by Nancy Owano weblog
Shiver me timbers. Architects plan wood skyscraper for resident life

(Phys.org) —HSB Stockholm, a building society in Sweden, will be 100 years old in 2023 and to mark the date it is staging its architectural competition 2023. One entrant already gaining lots of attention is Berg | C.F. Møller, which has a proposed design of a 34-story solar powered skyscraper made of wood—well, not entirely of wood, but enough of wood to raise interest. Berg | C.F. Møller Architects are working in partnership with architects Dinell Johansson and consultants Tyréns on a skyscraper that would be seen for miles. The other two competing teams are Equator Stockholm with Mojang (Minecraft) and Utopia Architects with Rosenberg Architects.

The wooden is gaining attention as "green" news because of the factor proposed. A number of points in wood's favor: C. F. Møller's team noted how timber production releases less carbon dioxide than steel or concrete production, at a time where construction accounts for 30 to 40 percent of the world's generated from humans. Concrete and steel command a large part of the market, but wood-supporters note that wood is a lightweight, renewable material that can bear heavy loads in relation to its weight.

Cost-wise, they say wood is cheaper to build and better for the environment than using steel-and-concrete for buildings. Wood costs less to transport due to its lightness, too. The C.F. Møller team is thinking in terms of a residential complex. While the building is made mostly of wood, it would have a concrete core. Wooden pillars, beams, walls, and ceilings in the plan are encased within a glass façade, with the walls, ceilings and window frames visible from the exterior through the large windows. Each apartment will have this glass-covered veranda, while the building itself will be powered by on the roof.

In general, the word "wood" makes some people nervous because of fears of fire. who favor wood, however, argue that wood is safer than other types of building materials and can be more fire resistant than both steel and concrete. Earlier this year, an article in the Toronto Sun took note of what Geoff Triggs, building code consultants expert, had to say about the use of wood in high-rise construction. Rather than using small two-by-fours super-compressed mass timber is used to make very large panels. The compressed lumber is as strong as concrete but lighter. The compression process creates dense wood blocks that are difficult to burn.

Explore further: Company pioneering new types of material for 3-D printer 'ink'

More information: www.cfmoller.com/r/Wooden-Skyscraper-i13265.html

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User comments : 18

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ubavontuba
1.8 / 5 (5) Jun 22, 2013
It certainly is attractive looking. But I have my doubts about the fire safety claims.

Although I can find other construction anouncements with similar claims:

example:
http://www.advant....en.html

...I can't find any corporate business which claims to be producing a wood product which is safer than steel and concrete in regards to fire resistance. However they do state it is lighter than concrete and safer in earthquakes.

The information I do find appears to emphasize wood's CO2 storage properties.

Here's a nice podcast which discusses the concepts:

http://eclipsenow...oncrete/

Can anyone else find anything regarding these claims regarding the fire resistance properties?

Neinsense99
3.2 / 5 (9) Jun 22, 2013
It certainly is attractive looking. But I have my doubts about the fire safety claims.

Although I can find other construction anouncements with similar claims:

example:
http://www.advant....en.html

Can anyone else find anything regarding these claims regarding the fire resistance properties?


Here is one link: http://www.aitc-g...ance.pdf
Neinsense99
3.2 / 5 (9) Jun 22, 2013
It certainly is attractive looking. But I have my doubts about the fire safety claims.

http://onlinelibr...abstract

http://www.cwc.ca...sistance
Neinsense99
3.2 / 5 (9) Jun 22, 2013
Look, Mom! A woody!
Humpty
2.7 / 5 (9) Jun 22, 2013
@ubavontuba

Perhaps a little more information, and less assumption is in order here.

Plain thick wooden beams, and columns, - in a big hot fire, burn through, over time, but when steel starts to get hot, it softens and yeilds. Concrete starts to spall from the internal steam pressure and blow bits of it's self out and it crumbles and fractures in a hot fire.

What they mean is that is a big hot fire, where the building will eventually be destroyed,, is that wooden framing, will last a lot longer and hold the building together, a lot longer than concrete or steel - so the safety aspect is that it gives a lot more time for everyone to evacuate, before the building collapses.

Secondly, compressed structural woods, can and are impregnated with fire retardant, and they basically char on the surface, in a big fire, but they don't "burn" like wood on a BBQ.

So go look up the fire ratings of the products, and all the fire protection systems for steel and concrete.
ubavontuba
1 / 5 (5) Jun 22, 2013
Hi Neinsense99,

Yeah, i saw those and similar links. They claim better structural integrity retention during a fire, but do not claim the timbers themselves resist fire better than steel and concrete. That is, they do not claim the timbers won't themselves serve as fuel for the fire, as with steel and concrete.

Where I live, we have many warehouses and shops built with this material, and I will agree it's an excellent material for lowrise buildings (not more than a few floors high). But in a vertical building it's combustible qualities would only seem to increase the likelihood of a catastrophic fire.

Here's a link which discusses "fireproofing" this form of construction with sprinklers:

http://www.theglo...5308574/

But I don't buy this as a safeguard as fire tends to be rather "sneaky."

continued...
ubavontuba
1 / 5 (5) Jun 22, 2013
...cont

I'm mostly concerned with fire's tendency to spread vertically. The folks trying to escape the upper floors could quickly be overwhelmed.

Also, here's an excerpt and a link which discusses some of the fire qualities of the interior siding materials used in this form of construction:

"Testing at the University of California Fire Research Laboratory has shown that, when ignited, compressed wood particle or fiber siding products and wood shingle siding will result in more rapid vertical flame spread up the wall"

http://www.firesa...t-siding

But overall I don't have an issue with it in isolated constructions, but I'm concerned multiple proximal constructions made of these materials could be a catastrophe in wait.

ubavontuba
1 / 5 (4) Jun 22, 2013
Look, Mom! A woody!
Okay, that was good. LOL
ubavontuba
1 / 5 (5) Jun 22, 2013
@ubavontuba

Perhaps a little more information, and less assumption is in order here.

Plain thick wooden beams, and columns, - in a big hot fire, burn through, over time, but when steel starts to get hot, it softens and yeilds. Concrete starts to spall from the internal steam pressure and blow bits of it's self out and it crumbles and fractures in a hot fire.

What they mean is that is a big hot fire, where the building will eventually be destroyed,, is that wooden framing, will last a lot longer and hold the building together, a lot longer than concrete or steel - so the safety aspect is that it gives a lot more time for everyone to evacuate, before the building collapses.
Of what good is structural integrity, when the room itself is on fire and the atmosphere is a poison?

Most people die from smoke inhalation in a fire, not building collapse.

Eikka
4.5 / 5 (2) Jun 22, 2013
Of what good is structural integrity, when the room itself is on fire and the atmosphere is a poison?


Having more time to put the fire out before the building collapses and knocks out other buildings.
ubavontuba
1.7 / 5 (6) Jun 22, 2013
Of what good is structural integrity, when the room itself is on fire and the atmosphere is a poison?


Having more time to put the fire out before the building collapses and knocks out other buildings.
That's an interesting point, but I fear the liklihood of the fire spreading throughout the bulding is greatly increased, ergo diminishing the possibility of minimizing and containing the fire to begin with.

Sadly, I guess we'll probably have to wait for one or more of these structures to burn, before these issues are well understood.

Eikka
5 / 5 (1) Jun 22, 2013
The main problem with wood is that it pyrolyzes at high temperatures. It's a composite material composed of fibers that contain mostly carbon, and a "glue" that is made of lignin, which is quite similiar to plastic. When you subject it to heat, the lignin breaks down and turns into combustible gas, leaving behind the carbon containing fibers, or charcoal. That's basically how cars were able to run on wood pellets during WW2. They used the heat from burning the charcoal to gasify lignin to power the car.

So in a building fire, you basically have gaseous fuel for the fire coming off of the very structure of the building even if the wooden structure is not technically on fire yet.

Torbjorn_Larsson_OM
5 / 5 (2) Jun 22, 2013
Interesting combination. Of course, a roman type concrete would likely be CO2 neutral, but the rest of the advantages are there.

@ubavontuba:

I am not going to do the work for you. As Humpty notes, the increased safety from using glued, compressed wood as opposed to steel beams when it comes to intense heat fires (e.g. after half an hour or so in a high rise fire), is often described in technical articles.

And it seems you are not really interested in the comparison as of finding fault in using wood. Because you start to discuss irrelevancies such as inner material behavior (room on fire, smoke poisoning). Yes, even compressed tree will eventually combust and char, and then contribute to flame spread relative to a steel/concrete surface. But that is at a time an inner room has been burned out already.

What architects are comparing is safety under and after a fire. And everyone finds "wood is safer than other types of building materials". IIRC I haven't seen even one contrary find.
Torbjorn_Larsson_OM
5 / 5 (2) Jun 22, 2013
@Eikka: Again, pyrolysis will happen at late stages in these materials, at high temperatures. Survivors would be elsewhere, in the fire resistant and ventilated stair wells (at least Sweden don't use elevators for fire escapes so far). I doubt the gases would contribute to the fire, seeing how little surface we are talking about (structural beams).

As for walls and ceilings, they could contribute more. But you have to remember that most people in Sweden chooses tree as a major part of the inner room structures, whether or not they live in wooden houses (as a large part of the outer city scapes do).
Eikka
5 / 5 (1) Jun 22, 2013
pyrolysis will happen at late stages in these materials, at high temperatures.


At around 400-500 degrees and up. The question is really, if you have a room fire in a high-rise, will the whole thing go up in flames, or do you just get smoke damage in the upper floors.

A building made out of materials that aren't fuel themselves won't see the fire spread as easily as having wood gas seeping through the frame of the building. Wood structures also sustain a smoldering fire that can remain hidden for a while, spreading inside the walls.

I've seen that happen once. A building was actually on fire from an electrical fault, but the fire was so oxygen starved that it kept going for a day before people started smelling the smoke coming from the rafters.
ubavontuba
1 / 5 (3) Jun 23, 2013
In 2011, two 6-storey wood frame condo buildings, under construction, burned spectacularly in Richmond, BC.

http://www.cbc.ca...ire.html

Obviously, these buildings were under construction so fire safety measures hadn't yet been completed, but one has to wonder, would this fire have occured at all to similar steel and concrete structures? It seems unlikely. Certainly, it seems the loss wouldn't have been nearly so complete.

Of particular interest is the effect this fire had on nearby structures.

toomuchtime
5 / 5 (2) Jun 23, 2013
the difference is that the building you are comparing is a wood frame, this project is using a heavy timber construction which exhibits different types of fire resistance.

Heavy timber will char but will not lose its strength right away, most the issues with fire resistance is not the fact that if it is going to burn or not, its more what is the waiting period before the sucker falls down.

For example, in 2001 when the world trade centers collapsed; if the construction was heavy timber construction then the building would not have weakened as quickly as it did and it may have saved hundreds of lives. I see your concern with toxic gases but those are not as devastating as a whole collapsing structure.
Eikka
5 / 5 (1) Jul 04, 2013
I see your concern with toxic gases but those are not as devastating as a whole collapsing structure.


It's not about the toxicity of the gasses, but the flammability of the gasses. As the wood frame chars, all the lignin in the wood pyrolyzes into methane, carbon monoxide and hydrogen, which then go on to fuel the flames that are burning the building down, accelerating the whole process.

So it's a rather moot point that wood can withstand a fire, when the fire burns hotter and faster because of the wood.

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