The International Code Council approves mass timber up to 18 stories.
Big wood, or heavy timber, has been in the building codes forever; that is how they built warehouses all over North America. But it has long been limited in height to about six storeys. According to Michael Kilkelly of Architect Magazine, the International Code Council (which really isn't international but is American and writes American codes, don't ask) has been looking at the issue of tall wood since 2015. He writes that TreeHugger favourite Susan Jones was involved:
Having designed four of the first mass timber buildings in the country, Susan Jones, FAIA, of Atelierjones in Seattle, was asked by the AIA to join the Tall Wood Buildings Committee, which she did in spring 2016. A first-time member of an ICC committee, Jones says she found the process invigorating: “It’s a great thing for architects to realize how knowledgeable we are, and how powerful that knowledge is if you give your time to it, pull your head up ever so slightly from your computer, and see what kind of change you can make.”
Historic day. Owners, architects and engineers will soon have a choice to build lower carbon mid- and high-rose buildings out of mass timber! #tallwood #ICCAC18 #icccodehearings2018 pic.twitter.com/C76lIQQWF4— Susan Jones (@atelierjones) October 25, 2018
The proposed rules would allow buildings up to 18 storeys or 270 feet tall, with the building fully sprinklered and all the wood fire protected, much like it was in the Brock Commons tower in Vancouver. In buildings up to 12 storeys, mass timber components could be exposed. Of course, the VP of regulation at the American Wood Council is excited about this; Kenneth Bland says in a press release:
Other nations have already seen the benefits of tall wood construction – from the low carbon footprint, ease of construction and reduced construction time. The tremendous support of tall mass timber construction seen at the ICC public comment hearings, and the positive outcome, is one more important step toward advancement of tall wood in the United States.
This is not a done deal yet; there is going to be an online vote with the final result coming in December, and the next big code revision that will include it is in 2021. Then individual jurisdictions have to adopt it. The concrete, masonry and steel people have been fighting it like mad and will continue to do so, so it will be interesting to see how that online vote goes. But as Susan Jones tells Kilkelly, “If we can build using lower carbon emitting materials … that sequester carbon, versus the choices we have today, then that’s a big impact and we’ve made a difference as an industry”.
This is, as Susan Jones and others have noted, an important step forward to low-carbon, low embodied-energy buildings built from renewable resources.
On the same day that the ICC approved the code changes, Michael Green was speaking at Wood At Work in Toronto. He noted that "trees are the planet's greatest invention." We are at the point where mass timber can replace wood and concrete for the majority of our buildings if the codes allow it. We are now well on the way, if the steel and concrete interests don't screw it all up.