In the tiny Scottish village of Crathie, the showcase studio of Moxon Architects nestles deep into the bowl of a former gravel quarry. Designed by the firm, which also has a London office, the project consists of three buildings: a large studio set back into the bowl landform, a café, and a storage garage. The studio and the café are joined by a covered walkway.
Over the years, the quarry had become a dumping ground, requiring the removal of material before construction could commence. But the site had also regrown with a stand of self-seeding birch, juniper, and heather, creating a natural setting that shelters the studio from the adjacent, busy road. The project’s design emphasizes the connection between indoors and outdoors: A clerestory window brings natural light across the studio’s monopitched ceiling, offices look out to a constructed wetland, and a screen wall of locally sourced Douglas fir timbers—the project’s centerpiece—weaves through site, connecting the café and design studio visually and physically.
The timber was harvested from a site near the childhood home of Moxon founder Ben Addy in the village of Birse in Aberdeenshire, Scotland. “When I was growing up, these trees were in the next door neighbor’s garden,” Addy says. The firm conceived the timber as a way to anchor the studio buildings to the landscape—the wood members morph into doors and a bench as well as centerpiece wall. The wall begins in the café, continues outside to the walkway, and enters the main studio building, where it screens the studio space from a less public model-building area.
The timber wall is interrupted by the building envelope where it transitions from outside to inside the office. “There’s a window at the break,” Addy says. “But it’s dealt with through detailing. The wall is exactly aligned inside and outside, and so you don’t really perceive the difference. It starts and stops on a piece of glass.”
Though the wall looks simply “like a stack of wood,” Addy says, its construction cleverly adapts to the challenges of employing a natural material that is prone to thermal movement, shrinkage, cracking, and checking. Steel rods run vertically through every timber piece in the stack, and the wood is bolted not only at the top of the stack but also intermittently, Addy says. “There are bolts that clamp the stack in rows of three, and then the whole lot is clamped together as well.” The members are secured into place, but have enough freedom of movement that they can split, shake, and shrink without trouble. “The wall is kind of geometrically perfect even while it starts to develop a life of its own within the stack,” Addy says. Where the wall intersects the columns supporting the roof, the timber members are flitched around the steel.
The 200-millimeter-square (7.9-inch-square) Douglas fir beams range in length from 200 millimeters to 3,805 millimeters (12.5 feet). End-to-end, the members total 1,676 lineal feet. The timbers are stained with Osmo Polyx-Oil, to protect them from the elements outdoors and to ease cleaning inside.
The project was constructed by Tor Contracting, owned also by Addy, making Moxon Architects the project’s client, architect, and contractor. This gave Moxon a high degree of control, which Addy notes was a major advantage. “No one else was involved,” he says. “That’s why we were able to do things such as the timber wall. A lot of builders would have looked at the detail and said, ‘That looks difficult’ or ‘We’re not sure how that will perform in use.’ But because we were very confident in it and we were building it ourselves, we could take the risk and do the experiment.”
That confidence comes in part from the nature of the material. The team investigated several lumber species, including larch and oak, says project architect Andrew Macpherson. They chose Douglas fir for its low natural moisture content. “Movement through thermal expansion and drying was expected, but the objective was to specify a timber that would not have pronounced warping, bowing, excessive shakes, or rotational movement,” he says. “The sections were air-dried for several months externally, then transported and stored in the space they would end up in for another couple of months. The timber walls are lifted slightly off the concrete slab and have a 10- to 15-millimeter gap on each end of every beam to allow for lateral expansion.”
Extensive modeling also helped to build confidence, Macpherson says. “Parametric CAD modelling, scheduling, and 3D printing were used to investigate the design,” he says. “3D printed models allowed each panel to be adjusted depending on their individual requirements before the timber arrived on-site. Once the design was agreed upon, fabrication drawings and cutting lists were created for a selected team of tradesmen who added their expertise with timber to achieve the desired finish.”
Each timber was planed before installation using an industrial planer Tor Contracting installed on-site. The team used the timber offcuts as pavers for the covered walkway, staining and setting them into a bed of bitumen over a concrete slab. “You’re walking on cobbles made of wood,” Addy says. “All of the wood that we bought has been used in the building.”