Twenty minutes into our discussion about the Smile—Alison Brooks Architects’ (ABA’s) forthcoming seesaw of a building in the courtyard of London’s Chelsea College of Arts—I’m still trying to determine what makes the upward curvature of the unusual, namesake form structurally feasible.
“The tube is the cantilever,” says Brooks, the principal and creative director of the London firm.
For the American Hardwood Export Council's (AHEC's) installation at the 2016 London Design Festival, in September, ABA has envisioned a 113-foot-long, 12-foot-high, and 15-foot-wide cross-laminated timber (CLT) pavilion that will appear poised for flight, with only a slight point of contact with the earth at its center. Here, a 25-foot-long timber cradle loaded with concrete counterweights procured from a local crane company, will be mostly buried underground—but not more than 3 feet below, lest it disturb archaeological remains of the 19th-century Millbank Prison, which ran beneath the college and the Tate Britain next door.
And, invariably to the dismay of some and to the relief of others, the installation will not rock side-to-side. The approximately 1,600-square-foot pavilion attaches to the footing with bolts, the only significant metal that will be used on site.
That is, of course, the point. CLT, an engineered, structural super-timber made from wood planks layered at perpendicular angles and bonded with heavy-duty adhesive, came to the fore as a viable alternative to steel and concrete more a decade ago. Recently, engineers have devised hardwood CLT, an even more robust material that architects covet for its lightness, high strength-to-weight ratio, and consistent, knot-free surface. “It’s got the color and grain of high-quality flooring,” Brooks says. “The quality looks too good to be structural.”
The Smile will be the world’s first completed building to use large, industrial-size hardwood CLT panels, and the world's first (of many more, Brooks hopes) timber mega-tube structure. “The unexpected curved form and two-way cantilever express the ability of the material to do exactly what steel can do—appear to defy gravity,” she says.
Anyone familiar with ABA's work knows that its founder is almost evangelical about wood and exterior wood paneling, in particular. Later this year, the studio will complete a cloister at Exeter College, in Oxford, England, built entirely of glulam.
The AHEC, which has an office in London, supplied the wood for that and past ABA projects. When it came time to brainstorm for the AHEC’s showcase at this year’s London Design Festival, European director David Venables invited Brooks to the table.
“Alison has always been a champion of clever, simple, workable design and is absolutely passionate about timber,” Venables says. “She was the perfect match for us to take this 10-year [investigation and experiment with hardwood CLT] to the next level.”
You could read the Smile as a physical metaphor for the partnership, a larger-than-life, happy emoji. It seems to have come at a time when both ABA and the AHEC were seeking new ventures with CLT. “[The Exeter project] made me think how fantastic it would be to work with hardwood glulam because it has greater strength and is so much better looking,” Brooks says. She and Venables settled on tulipwood CLT, an inexpensive, low-grade material from an abundant wood known as yellow poplar in the U.S.
“Working with it as a panel material—it’s the future,” Brooks says. “It’s where we need to go to be working in a more sustainable, carbon-positive state of mind. But you have to have it tested and certified before certain contractors will work with it.”
The Smile is just that test.
In designing the four-sided tube with engineering firm Arup, ABA has beefed up the CLT construction to have the collective strength of a steel-supported structure. That strength is what gives the pavilion its capacity to bend upward and balance without tumbling over, like a gymnast springing into a handstand. And size matters. With the twin 51-foot-long cantilevers able to hold 60 visitors each, the Smile will appear to do the near impossible. “When you load it up with people, [you understand] that it can support live loads,” Brooks says.
Inhabiting the Smile will be a trip. Visitors will enter at the inverted arch’s point of tangency with the ground and ascend the cantilever ramps to open terraces that look up and out into the sky. Surrounded by the fresh scent and honey tone of tulipwood, Brooks says, “you will feel like you’re inside the wood itself.”
In the factory of German manufacturer Züblin Timber, the CLT panels will be pre-drilled with perforations inspired by a stress analysis of the structure conducted by Arup. The holes will translate a complex pattern of forces, clustering where there is less tension and compression in the wood—and thus less need for material—and dispersing where the stresses are higher. These perforations will let in dappled light during the day and release light from the inside out at night, turning the Smile into a warm, glowing lantern.
Or, as Brooks describes it, the Smile will be “something between a landscape, an adventure playground, and a weightless funnel of space and light.”
The Smile will be installed on the campus of Chelsea College of Arts, in London, from Sept. 17 to Oct. 12, as part of the London Design Festival.