The case for making cities out of wood

The main obstacle to this outcome—what a 2016 paper called “a full timber building renaissance”—is the public’s fear of city fires, which has been reflected over centuries in construction codes globally. Some researchers, like Alastair Bartlett, at the University of Edinburgh, see in these obstacles an “opportunity,” as he wrote in a 2017 study, “to revisit compartment fire behaviour and to quantify the impact of these new construction technologies on the compartment fire dynamics.”

Bartlett, along with some colleagues, tested the sort of wood mid- and high-rise buildings—like Framework, in Portland—have recently been made out of, known in the industry as “cross-laminated” or “mass” or “tall” timber, which is how Quayside’s developers refer to it. Bartlett set up three rooms of equal size, about as big as a large walk-in closet. Two of the rooms had two exposed surfaces of timber (one with two walls exposed, the other a wall and the ceiling); the last room had two walls and the ceiling exposed (non-exposed surfaces were covered with plasterboard). Each room had four wooden “cribs,” or pallets, for the “fuel load,” placed on the ground, one of which was lit using fiber strips soaked in paraffin. Bartlett then documented how fast and how hot each room burned. The room with an exposed wall and ceiling managed to “auto-extinct”—the fire went out by itself. This depended “on the char layer [of the wood] remaining attached” rather than falling off while the cribs were burning, Bartlett concluded. He wants to do many more experiments because it’s still not clear how, in mass timber buildings, to get compartment fires to reliably burn out on their own, a “cornerstone of fire safety engineering design,” he writes. “The failure modes of common compartment construction systems and materials are relatively poorly documented from a scientific (rather than compliance testing) perspective.”