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Code Changes for Taller Wood Structures

jar546

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SALEM, Ore. - The State of Oregon Building Codes Structures Board recently approved and the Oregon Building Codes Division adopted code language providing for taller wood building construction in Oregon.

The Aug. 1 approval provides greater predictability for owners, developers, contractors, and designers to have additional choices in construction. Oregon is the first state to take such a step at the state level, providing an ..................

https://www.ktvz.com/news/state-sets-standards-for-taller-wood-buildings/779249158
 
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Canada added provisions for 5-6 storey wood in the most recent code and it looks like we will see provisions for 18 storey CLT in the next one. Nice to see others headed in the same direction.
 
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Approved, up to 101 feet!
"But the bulk of the savings will be achieved through a combination of energy-efficient and sustainable features, Goodwin said, including self-generated solar power, a (vegetated) green roof, non-toxic materials and framing harvested from fast-growth timber. The structure will be one of only a handful of tall timber-framed office buildings in the United States, McDonough said."

https://www.dailyprogress.com/reale...cle_9414ac0e-1ceb-11e8-8cb7-cf57bc3aec19.html
 
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Pretty sure the code change proposal was given to me to read a while back. I was not a fan of it, and will vote no. The proposal was to add a lot of code, such as entire new construction types and sub-types and re-writing a lot of other code. I am not passing judgement on the concept, but right now I don't think we need to re-invent the wheel for a few novelty buildings. Maybe we should give it a while, maybe work out some bugs, see if it sticks, and let them be approved as an alternative or performance based design before we throw all that new code into the books.
 
An email from yesterday:


National Poll: Three in Four Americans Think
Tall Wood Construction is a Threat to Public Safety


Strong, Widespread Concern Raised by Proposals to Expand
High-Rise Construction Using Wood



Washington, D.C., Aug. 14, 2018 – Three in four or 74 percent of Americans say proposals to allow taller buildings to be constructed with wood raise serious concerns for public safety, according to a new national public opinion poll. When asked about proposals to change the nation’s model building codes to raise to 18 the number of stories that can be built using wood products, respondents expressed worry over building structure and fire safety. These proposals will be voted on in October by the International Code Council (ICC), which develops the model building code.

“Most people don’t know what materials were used to build their home, school, hospital or office building – so the building codes that shaped those construction decisions are way off their radar,” said Portland Cement Association (PCA) President and CEO Michael Ireland. “We wanted to take the pulse of Americans to learn what they think about proposals to build taller structures using wood, and we got a very clear picture: they don’t like it.”

According to the nationwide poll conducted by Hart Research on behalf of PCA, three in four respondents, or 74 percent, think it’s a bad idea to allow high-rise construction using wood. Further, three in four respondents, or 74 percent, also say they’d be personally uncomfortable doing business in buildings built using wood products, such as cross-laminated timber.

When asked why they had concerns about such proposals, the following percentage of respondents volunteered specific reasons, which are summarized here:

  • Wood is less strong than other building materials like steel and concrete, it’s not as sturdy or durable and could break (52%)
  • Wood is more flammable, more likely to burn, and presents a greater fire hazard (31%)
  • Wood is more susceptible to weather damage and weather events (including earthquakes & hurricanes), it is less safe and will decompose or rot faster than other materials (18%)
“It’s time Americans were made aware of this threat, and that they can have a say in whether the wood industry gets a fast-tracked path to being able to build high-rise buildings across the country,” Ireland said, urging people to visit https://stoptallwood.com to get engaged.
 
I bet a majority of contractors and building code people do not even know what or how CLT is built or performs in a fire. So a public opinion poll put on by the Portland Cement Association hold zero weight with me. They may be more susceptible to earthquake damage if the standard screw fasteners produced in the US are used because they are more brittle and may snap during a seismic event compared to European made fasteners that have been designed to work with CLT.
Personally I do believe 18 stories (180ft) is excessive at this time. I would prefer to limit them to 10 or 12 stories (120 ft) until we or Europe has had some real world fire event and see how they preformed.

Not all CLT manufactures are the same in their manufacturing process

3 3 CONCLUSIONS
Basically, the major difference of the two standards for
CLT is the main principle. The US standard has 29 pages
and makes except the tables of the modulus of elasticity
and bending and few minor other topics such as
dimensional deviations references to standards from
glued laminated timber and other wood panels products
such as LVL. Primarily it is due to the fact that until now
there is now production in the US and therefore also very
limited experience and studies on various topics on this
product. Whereas in Europe it has grown over the last
about 15 years and by the steady development also the
standard was created but not until 2013. The current EN
standard for CLT has 95 pages and has much more
detailed specifications then the US standard has

(PDF) Comparisons of the production standards.... Available from: https://www.researchgate.net/public...oss_laminated_timber_CLT_in_Europe_versus_USA [accessed Aug 16 2018].
https://www.researchgate.net/public...oss_laminated_timber_CLT_in_Europe_versus_USA
 
Cement guys are always going to be down on the wood guys, and vice-versa - that's why I just copied-pasted and didn't comment.

I agree that going straight to 18 stories is probably not the best course of action. There's no need to get there all in one go, seems to me we ought to take our time and see how some of them do in real life before we just jump in with both feet. But the guy with the money makes the rules, so if the wood guys stack the hearings with more voters than the concrete guys do, well........
 
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We have one in BC that is 18 stories.
The proposal included reviews of current 18 storey wood building in the US and Europe and compared fires in the completed buildings to those in non-combustible buildings. oddly enough, there was no increase in the damages once all the fire separations are in place.
 
I have seen other testing from the AWC on CLT, it is amazing how it holds up. protected, and unprotected........here is a quick peek.

 
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