CityLab reporter Laura Bliss resurrected an old quip about California after the 2019 fire season: “Living on ground that so readily burns, shakes, and slides was the state’s original sin,” and it will teach us a lesson someday. Given the rising threats posed by a globalizing state and a warming planet, it may appear that lessons have finally begun to be learned. Nonetheless, more than 39 million people call California home, so the narrative must shift from “Should we live here?” to “How should we live here?”
Many of California’s native plant and animal species rely on wildfires for their survival because they remove dead, nutrient-depleting material, kill illnesses, and make ideal conditions for seed germination. There is a strong correlation between the longer climatic shifts and the longer weather cycles, which affect their occurrence on an hourly and seasonal basis. The recent and expected increases in air aridity caused by global warming are worsening fire-friendly conditions.
According to the California Department of Forestry and Fire Protection, more than 2.7 million people in the state resided in “extremely high” fire threat zones in 2018. The amount of fuel produced by the local ecosystem and the likelihood of igniting owing to local human factors and climatic circumstances are the two primary factors used to arrive at the grade. Wildfires have been suppressed for the previous 70 years, which has greatly increased fuel and the likelihood of major fire.
Wildland-urban interface (WUI) refers to the transition zone between developed areas and undeveloped wilderness; this zone encompasses a large portion of the foothills in California and is experiencing a rising fire risk. In the future, today’s fires will likely appear trivial in comparison. Due to the devastating consequences of record-breaking wildfires on human settlements, the question becomes how to live in harmony with fire. Our newest solutions are showcased in four different case studies.
A cast-in-place concrete guesthouse designed by Mork-Ulnes Architects (MUA) was finished in 2017 next to a wood-framed house in the foothills beyond Sonoma. A devastating fire ripped through the neighborhood in October of that year, destroying the older home but sparing the Ridge House thanks to the chemically inert concrete’s resistance to heat transfer.
Concrete was the obvious material of choice when MUA was commissioned to reconstruct the main home. The customer was interested in wood, but not in CLT just yet. (The California Building Code of the time wasn’t much better.) The concrete, glass, and CMU building is more cost-effective and spacious than its predecessor, and its concrete frame will likely last for decades or centuries.
Casper Mork-Ulnes, who runs the business out of Oslo, Norway and San Francisco, wants the building to stand “like an Italian fortress” for centuries to come. Having a structure that will last for a long time is a plus, especially in high-risk areas for fires. He confidently predicted that the house would not need to be replaced more than twice in the following half-century, let alone four times during the next two centuries.
Olson Kundig built a home for Greg and Lesa Faulkner in a former logging area of the Sierra Nevada near Lake Tahoe; as a result, the safety of their family was prioritized in the construction of the structure above everything else. (Greg is the head of the Truckee and Berkeley locations of Faulkner Architects.) Home stability is ensured by double-layer, 8-inches-thick concrete walls filled with closed-cell insulation on the inside. The external decks are clad in basalt stone tile, and the exterior timber soffits are supported by one-hour rated gypsum assemblies. Crushed basalt aggregate serves as a shield for the roof above the heavy timber deck. 10-gauge weathering steel covers the walls that are framed with wood. With the steel furred off the wall, the space can be stuffed with rock wool insulation to reduce heat gain. Despite being situated in a dense pine forest, the architects claim that the house was given a perfect score of 10 out of 10 for fire safety when a new policy of fire insurance was obtained.
An intricate strategy that takes into account the interconnectedness of urban, suburban, and rural issues will be necessary in the coming decades. A severe housing shortage has plagued the Golden State since the 1970s. Dr. Sarah Mawhorter of UC Berkeley’s Terner Center for Housing Innovation found that between 2007 and 2017, the Golden State experienced a production shortage of 1.1 million units. For the past fifty years, there has been an insufficiency of design interventions that effectively tackle 21st-century problems due to a reluctance to exceed existing strategies. Although rigorous regulations on where construction can take place are necessary, “there still need to be deliberate development and a good amount of density,” according to SWA’s Watkins.