Earlier this fall, I wrote up a forthcoming Toronto condominium block to be fashioned chiefly from the high-performance forest product known as cross-laminated timber (CLT). This material, I understood, had been receiving enthusiastic notice by forward-looking architects and engineers in North America and especially in Europe. The launch of this mid-rise condo stack in the Beaches neighbourhood was news: It was the first residential project made of CLT to come forward in this city since last January, when Ontario lifted the upper limit of wood-framed buildings to six storeys.
Less newsworthy was the artistic design, which I found dowdy. In the review, I blamed the hum-drum art of the building on its cutting-edge stuff: “If I hesitate to cheer for this structural advance – which is surely desirable for all the reasons its fans put forward – it’s because CLT framing doesn’t really lend itself to artistic invention of the fresh sort cities need nowadays. The system appears to resist curving and bending and formal jogging or syncopation – the imaginative design moves, in other words, that contemporary digital modelling encourages and that steel makes possible.”
These remarks drew a quick reply from Toronto architect David Warne, who had designed (while full-time with LGA Architectural Partners) a CLT-framed wing of the new architecture school at Laurentian University, in Sudbury. “I just wanted you to know that CLT can do quite fantastic things,” Mr. Warne wrote. He attached to his e-mail some images meant to prove his point.
They did so, and I stand corrected.
When I wrote about the condo building, I did not know, for example, about the remarkable wooden roof of the Kaeng Krachan Elephant Park at the Zurich zoo. This vast wildlife pavilion, crafted by the Swiss firm of Markus Schietsch Architekten, features a curving, wavy dome made of prefabricated triple-layer panels. The fabric is penetrated by 271 plastic skylights. In the words of the architects, “the roof dissolves into a transparent maze-like structure that establishes an organic relationship to the surrounding forest.” The pictures of the dome, which is supposed to suggest the interlacing branches of trees, indicate that CLT can indeed be as dramatic as steel.
Steel, of course, won’t be replaced by CLT – at least not for a while. But the material can raise the emotional temperature of a project that, were it executed in steel alone, would probably seem cold and inert. In his highly theatrical new headquarters of the Fondation Jérôme Seydoux-Pathé in Paris – a blogger called the structure a “stuck armadillo” – Renzo Piano has used laminated timbers (along with steel) to frame the building’s curvaceous glass canopy. The effects of the wooden vaults (and wooden floors and furnishings), if photos can be believed, include the softening and warming of an brightly skylit interior that might otherwise be uncomfortably hard.
Mr. Warne’s most intriguing images, however, illustrate the marvellously eccentric, hugely controversial, wildly overbudget CLT contraption known as the Metropol Parasol, completed in Seville’s old market quarter four years ago. Designed by Berlin architect Jurgen Mayer H , this swirling ensemble of wooden parts glued together demonstrates that CLT can certainly be made to express every architect’s (computer-assisted) fancy, however flamboyant and improbable.
A critic writing in The Guardian, in search of a word, called it a “cloud,” a clump of “mushrooms,” umbrellas, even a “waffle.” In fact, as the same critic notes, the 90-foot-tall composition contains a market, stores, a museum of Roman antiquities unearthed on the site, a rooftop restaurant, and a “winding, undulating” walkway for strolling above the ancient streets. It also provides welcome shade in a city with hot summers.
According to other published reports, the structural engineers decided, at a couple of points along the way, that Metropol Parasol couldn’t be built as designed. But Mr. Mayer H and the technical people eventually came up with something that was doable and that didn’t compromise the architect’s vision – and the strange structure went up in the heart of Seville.
Not every city needs (or wants, or could tolerate) a Metropol Parasol. But this project, and others that Mr. Warne brought to my attention, show that I was wrong to think that CLT construction is doomed to be boring. As the technology catches on, and as production becomes cheaper, we can expect to see CLT deployed more and more imaginatively, even in a mid-rise condo building.
The cybernetic hardware and software are already in place for such a development, and so are the computer-driven tools necessary for precision-cutting the wood.
Canada surely has no shortage of trees. CLT, David Warne believes, is “the material of the future.”