t is hard to imagine a wood-frame building without a veritable puzzle of cross-bracing. But Waugh Thistleton Architects accomplished it with Murray Grove, a multifamily building in the London borough of Hackney. The firm designed the nine-story structure using a cross-laminated timber product from KLH, an Austrian company—the result being, the architects say, the world’s tallest modern wood-frame residential building.
KLH’s system of horizontal beams and vertical structural wall boards is manufactured from spruce grown in sustainable forests. The spruce strips are stacked crosswise three layers thick and glued together. For Murray Grove, Waugh Thistleton used KLH’s product to create a right-angled matrix in which the structural walls differ in placement on each of the nine floors. Larger apartments are located on the lower floors and smaller ones on the upper floors, allowing for the structural walls to be carefully placed to minimize the load on each individual wooden beam. Thanks to the material’s integral cross-lamination, the loads are transferred both vertically and horizontally without cross-bracing.
KLH was nothing new to the architects. “We had used KLH four years earlier on an extension of a three-story building in London,” says partner Anthony Thistleton. “Since then, we have been looking at other uses of the material.” The Murray Grove project provided the right opportunity. Not only did KLH allow the architects to push the envelope in terms of the height of a wood building, it also helped the project meet the city’s renewables target for new construction: The team proved that the carbon saved through the use of KLH’s product was equal to the amount saved by putting a wind turbine on the roof for 210 years.
Another unanticipated benefit was that the use of timber sped up the construction process, allowing the entire structural frame to be completed by four people in 27 days, using little more than a portable crane and handheld electric screwdrivers. “One of the main issues on site was that we had to keep accelerating the schedule,” says Thistleton. “In a concrete building, running the electrical requires a couple of guys with a great hydraulic drill burrowing into the concrete. They can only work so long each day. Our electrical fix was supposed to take eight weeks. It took three.”
The new building system is not without its drawbacks—flat owners will need to consult an engineer before cutting a door between rooms—but Waugh Thistleton plans to keep using KLH, next time in an even taller building.