For years as a student, I dissected wooden construction details in Detail, wondering why they appeared so foreign to my American eyes. After a long and difficult search, the answer became apparent: Cross Laminated Timber (CLT). As a young architecture praktikant in Germany, I quickly realized everything I knew about wooden construction was outdated, inefficient and irrelevant. My first experience with modern European timber practices was a polycarbonate-wrapped house that utilized brettstapel (mfr: Bresta).
Brettstapel is, effectively, 2x boards mounted on dowels that are fabricated off-site and erected as panels. Quick, easy, effing brilliant. Brettstapel can be utilized for walls, floors and roofs. The products are available in various dimensions for acoustic and visual preferences.
From here, my spidey-intern senses went nuts, and I realized that there was something very desirable, very sexy about these panels. It comes pre-finished, installs quickly, incorporates low-grade rapid-growth lumber effectively, sequesters carbon and can be optimized for thermal storage (a topic for the next post). Amazingly, building with CLT is like building study models with chipboard – you place a window wherever you want.
Cross Laminated Timber is made by laminating dimensional lumber at right angles, similar to plywood – on steroids. The result is a prefinished material (optional) that is dimensionally stable, capable of spanning large distances, reduces construction waste, increases airtightness and can be rapidly erected. The cross lamination decreases swelling/movement and thicker panels don’t require a vapor barrier. The prefabricated panels can be brought into challenging sites, as in Hermann Kaufmann’s Olpererhütte in the Austrian Alps – helicopters lifted the panels to the construction site 2,400m above sea level.
CLT technology has been perfected in the Bregenzerwald (surprised?) and is utilized on projects all over the world, including the Österreich-Haus for Team Austria in Whistler.
Recently, a 9-story building by Waugh Thistleton was completed in London. Except for the foundation and ground floor, the entire building – including elevator and stair cores – is composed of CLT panels. Woodworks has an excellent pdf on the 9 week erection process. This is ‘platform framing’ for modern engineers. And speaking of engineers, CLT could prove to be extremely beneficial in seismic areas, as seen by this simulated quake on a 7 story CLT mock-up.
Hopefully, the Austria House in B.C. will have a positive regional impact. I contacted Weyerhauser several years ago about CLT, they said they weren’t interested and there wasn’t a U.S. market for it. Apparently Weyerhauser didn’t want to expand their client base and have opted to let the Austrians invade. Earth to struggling lumber plants: the Canadian Wood Council is on board. Perhaps the process of testing and approval for the U.S. market may be a hinderance at present, but who doesn’t to build with these?!?