Cross-Laminated Timber

Re:Cross-Laminated Timber by buss on Monday October 07, 2019 @04:55PM (#21185845)

Here in San Francisco, CLT won't be legal for buildings over six floors until about 2023 because of dumb policies. California uses the International Building Code as its base building code and then modifies it based on particular laws we have here. This modification & ratification process takes about two years. Then San Francisco does the same thing, adding another two to three years (because surely _our_ engineers are better than a consortium of the world's best structural engineers...)

The 2018 International Building Code provides codes for tall CLT structures, which won't get adopted in the CA code until late 2020, which won't get adopted in the SF code until late 2022 or 2023. At that point, developers can start applying for permits for CLT buildings, which takes about four to five years. Then add two years of construction.

So SF won't see CLT structures over six floors until about 2030. Makes you realize how unseriously we're taking climate change when the only carbon-negative structural building material in existence won't exist here for another decade.

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Re:Cross-Laminated Timber by d-sc on Monday October 07, 2019 @08:35PM (#21187507)

The process you describes is kinda a safety net. Buildings aren’t like software where you can continuously design and push updates. You get one shot and mistakes are very expensive.

If you want to change the environment right now, build buildings that let people live closer to work and commute less.

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Re:Cross-Laminated Timber by abakker on Monday October 07, 2019 @11:42PM (#21188534)

I mean, someone signed off on the footings of the millennium tower, too. SF is not taking a cautious, informed approach, they’re just burying their heads in the sand.

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Re:Cross-Laminated Timber by wahern on Tuesday October 08, 2019 @02:52AM (#21189473)

Friction piles are used around the world, including in far more seismically active areas like Japan. In fact, in many ways they can be advantageous. I don't think I've read a single article on the Millennium Tower where a professional claimed that the tower engineers did anything but apply proper, modern structural engineering. At best the few criticisms are more like, "but I wouldn't have done it."

When unexpected things happen it doesn't always mean anything was done wrong, or even that anything should be done differently in the future.

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Re:Cross-Laminated Timber by TylerE on Tuesday October 08, 2019 @12:37AM (#21188813)

Especially it seems SF is an area where it would seem wise to be a bit extra cautious...since you're both seismically active and in a marine environment.

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Re:Cross-Laminated Timber by qwhelan on Tuesday October 08, 2019 @02:41AM (#21189412)

You are more cautious than the SF city government - basically all of the recent (and future) construction is in the most seismically unsound parts of the city!

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Re:Cross-Laminated Timber by rayiner on Monday October 07, 2019 @07:06PM (#21186937)

> At that point, developers can start applying for permits for CLT buildings, which takes about four to five years. Then add two years of construction.

Permits take longer than the building?!

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Re:Cross-Laminated Timber by nwallin on Tuesday October 08, 2019 @12:07AM (#21188671)

I subscribe to HN for the insights into technical subjects I might not otherwise have exposure to. My primary takeaway has been "this is why we can't have nice things", whether it's safe air travel, affordable housing, or affordable healthcare.

Demolition on the Waldorf-Astoria began on October 1st 1929. Unforeseen financial difficulties slowed progress. Construction began January 22nd 1930. The steel structure of the Empire State Building was completed on September 19th 1930. Construction was completed April 11th 1931.

These days it's more difficult- impossible- to get permitting for low rise medium density housing buildings in a city with significantly more financial resources and significantly more demand for floorspace.

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Re:Cross-Laminated Timber by chipsa on Monday October 07, 2019 @07:40PM (#21187175)

This is one of the reasons why housing prices in the Bay Area are always increasing. They literally can't build enough, and so what they do build is going to be expensive, because that's what's profitable.

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Re:Cross-Laminated Timber by buss on Monday October 07, 2019 @09:58PM (#21187929)

Pretty much every time

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Re:Cross-Laminated Timber by watersb on Monday October 07, 2019 @07:06PM (#21186936)

I am guessing some of this delay springs from the Loma Prieta Earthquake (1989).

Lots of structural retrofit there.

Yet I also guess that lessons from big quakes have been a part of the IBC review process. For decades.

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Re:Cross-Laminated Timber by Gibbon1 on Monday October 07, 2019 @10:37PM (#21188136)

Yeah every time there is an earthquake they learn how new modern materials and construction techniques fail and perform worse than the previous ones.

Kinda of like how joints in steel frame buildings held together with stupid janky rivets would shift and creek during earthquakes while strong modern welded ones wouldn't . Progress! No wait that last bit is bad. The steel at the welded joint buckles unless carefully designed. Which they weren't for the first 30-40 years.

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