Tokyo to build 350m tower made of wood

[jakewins]

Fire safety in wooden structures is interesting. A friend who does research in the area explained that, in some ways, wooden beams are simpler to engineer than steel beams when dealing with fire.

The goal, engineering wise, is to put a number on a given structure - how many hours can it burn before it falls?

A steel beam will maintain most of its strength up to the point it suddenly becomes soft and loses all of it. The exact point in time this occurs is hard to predict, because it varies substantially with several variables.

A wood beam will maintain the full strength of the beam, minus the average thickness of wood that is burned off per hour, which is a reasonably well known quantity.

This makes it simple (though not easy, of course!), relative to steel structures, to put a number on a wooden structure - "this building can burn for 2 hours before it is no longer safe for firemen to try to put it out from inside".

[tbabb]

The question is: how does the number for a steel structure compare to that of a steel one?

[tromp]

Currently under construction is this 73m tall residential wooden tower in Amsterdam:

https://hautamsterdam.nl/en/

The name HAUT appears to be a play on the Dutch word for wood (HOUT) and the french word for tall (HAUTE).

[mikeash]

Note that “haute” is the feminine form, and the masculine version of tall is just “haut.”

[toomuchtodo]

Those condo prices are eye watering (€1 million+).

[agumonkey]

I wish France and other would follow on building wood based punscrapers

[oever]

Here's a site with more information on wooden skyscrapers. It has a design for a wooden empire state building.

https://www.metsawood.com/global/Campaigns/planb/cases/woode...

[swampthinker]

Very interesting! But there is quite literally zero cross-bracing in that structure, which leads me to believe this was designed by an architect and not a structural engineer.

[steve19]

They plan on finishing it in 2041, more than two decades away. I think this sounds far more like a marketing ploy than an actual building project.

[KhanMahGretsch]

Japan is unrivaled in building long-lasting wooden structures using only joinery (no nails, screws). This allows the wood to expand and contract harmoniously without cracking. Multi-story buildings (temples are a great example) have “floating” stories than may shift several feet during an earthquake, all kept together with a freestanding “spine” mounted only to the ground.

[pimmen]

Is it harder to build this thing resistant to earthquakes than if it was made out of steel and concrete?

[armada651]

So Tokyo is finally going to build a Skytree made of actual wood this time?

[prostoalex]

Having just paid for a termite inspection, are infestations not a risk?

[baud147258]

I first read that as thermite and I asked myself how does it work with wood buildings. (even if, as per this thread, wood is better regarding heat)

[swampthinker]

Not if the lumber is pressure treated.

[querulous]

structural wood is almost always treated with boron to prevent insect infestation

[foobarbazetc]

Is there a good article on fire safety in these buildings?

[remontoire]

It's probably safer than steel frame buildings

https://www.economist.com/news/science-and-technology/216369...

[anonymous5133]

Curious as well. Seems like it would be a death trap and help spread the fire more.

[m3kw9]

Adhering to fire codes must be big part of the costs. How do you fireproof some crazy dude just decides to throw a Molotov cocktail at it?

[mseebach]

I don't remember the details, but on a previous article on wooden skyscapers, it was explained how the engineering of the wood, which is also required for the necessary structural strength, made it very dense and practically incombustible. Fire proofing is an inherent quality, not something that's applied and thus could be done poorly.

IIRC.

[bparsons]

The wood is all treated and sealed, so flammability is largely mitigated.

Even with steel, the actual frame of the building is surrounded by firewalls, fire resistant insulation and various suppression systems.

[faragon]

"The W350 tower will be mostly wood, and 10% steel."

Wood and steel.

[imtringued]

You might as well call it a steel tower at this point.

Steel is heavy but it's also very strong. You don't need a lot of it to build something. A pure steel building actually ends up being lighter than a concrete building because of this.

[incompatible]

I have a certain dislike for wooden houses because a) they seem to have high maintenance requirements, since wood as an organic material is often attacked by fungi, mould, or insects b) the ones I've lived in were old buildings lacking insulation and draughty, thus freezing in winter. That could be fixed with insulation of course.

[swampthinker]

It's actually less about insulation and more about air sealing. A hermetically sealed home with no insulation is generally warmer than a leaky home with walls stuffed with insulation.

Also regarding wood, this isn't the kind of wood you're thinking of. It's called pressure treated lumber, and it's an order of magnitude stronger than normal wood. The lumber has preservatives injected specifically to prevent rot, insect damage, and fire resistance.

[alva]

Regarding a), it very much depends on how they are built. Little Moreton Hall has been standing since 1504, subsequent restorations required no changes to the timber structure. Isn't it beautiful? Although I suspect it is definitely subject to point b)!

https://en.wikipedia.org/wiki/Little_Moreton_Hall#/media/Fil...

[jotm]

Bricks (everywhere, internal walls and all) and concrete (for the floors) are the best - no stupid squeaking, nothing to rot, nothing to break, great soundproofing, good thermal insulation if done right, will last a long time provided no natural disasters. Not even expensive depending on the region.

That said, I don't get the point of a wooden skyscraper. I'd guess it's earthquake resistant, and it's not actual natural wood but a mix of synthetic materials and wood.

[emilfihlman]

Make no mistake here: the wood used in this will be chemically sealed and pretty much inert. It's actually hazardous waste.

[y123y]

It's just a proposal/advertisement of one company.