Wildfire-Adapted Design

Out of the Ashes: Architects rethink residential design strategies in the wake of last year’s destructive California wildfires.
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Architectural Record
By Joann Gonchar, FAIA
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As the rebuilding effort gets off the ground, other architects are putting forward ideas to bring life to devastated neighborhoods. For instance, Byron Kuth and Elizabeth Ranieri, principals of the San Francisco firm Kuth Ranieri, propose small popup shelters that could be distributed throughout a neighborhood and offer shade, cell phone charging powered by rooftop photovoltaic panels (PVs), and a place where homeowners could meet with their contractor or architect. They are also proponents of easing restrictions on accessory dwelling units—often referred to derisively as mother-in-law apartments. Such structures, which many jurisdictions have frowned upon because they increase density, could allow homeowners to rebuild in phases, serving first as their short-term housing before being turned into a home office or a rental apartment.

As design teams start to develop long-term solutions, they will need to consider vegetation along with structure. “Almost every bit of landscape acts as a fuel,” warns Stephanie Landregan, the former chief landscape ­architect of the Mountains Recreation & Conser­vation Authority, an agency dedicated to the preservation of open space and parkland in and around Los Angeles. Among her recommended strategies are a defensible space around buildings, use of water-retaining plants such as succulents, and avoidance of branches that overhang the roof.

But before building or planting anything in a fire-ravaged landscape, project teams will have to prepare the land, including stabilizing sites and grading. These operations can help prevent catastrophic events like the mudslides that occurred in the immediate aftermath of the Thomas Fire. The procedures can provide important safeguards against more insidious erosion and runoff collecting in storm drains and polluting rivers and streams. In Califor­nia, the Army Corps of Engineers has removed much of the scorched debris and ash, which contain heavy metals and other toxins. However, runoff from exposed slopes denuded of vegetation, and the sediment it carries with it, still poses a threat to aquatic ecosystems, according to Jessica Pollitz, a project manager in the Petaluma office of civil consultants Sherwood Design Engineers. (Her firm is working on several post-fire residential projects in the north Bay Area, including one with Kuth Ranieri). In some cases the charred soil can become hydrophobic, further hindering infiltration and exacerbating the problem, she points out.

Architects involved in the recovery effort and looking for fire-resistant precedents can be found elsewhere, not just in California, or the United States. One designer who created his practice around wildfire design is Ian Weir, an architect and landscape architect based in Brisbane, Australia. He advises that anyone building in areas prone to wildfires (or bushfires, as they are known there) prioritize fire-resilient construction strategies over site clearing and management of surrounding vegetation. It isn’t practical to assume that such landscape maintenance activities will be performed in perpetuity, he says.

House built with architectural design for firefighting and wildfires

PHOTOGRAPHY: © NIKOLAS KOENIG

RUGGED REFUGE
A house atop a promontory in Montecito, California, has garage-style doors that can be rolled down to protect its glazed facades. The swimming pool water can be used for firefighting if necessary.

An illustration of this principle is the Karri Fire House, completed in 2014 within a mature eucalyptus forest outside the town of Denmark in western Australia. The bar-shaped, three-bedroom residence for a firefighter and his family, designed in collaboration with Queensland-based architect Kylie Feher, has one masonry wall but is otherwise supported by a shop-fabricated steel frame that cantilevers over the steeply sloping site. Galvanized cladding, intended to reflect the radiant heat of a bushfire, covers the roof and three facades. Underneath is a noncombustible fabric membrane similar to that used in firefighting apparel.

Many of the house’s features perform double, even triple duty, helping conserve energy and improve comfort, in addition to maximizing fire resistance. For instance, the masonry wall—which incorporates a fireproof cavity—along with the suspended concrete floor, provides thermal mass to help modulate indoor temperature. Metal screens can be rolled down over the east-facing facade, which consists of sliding glass doors. These can be used on a daily basis to shield the interior from heat gain and glare from the intense afternoon sun, as well as keep out insects while letting the breezes in. They can also be lowered during periods of fire risk to protect the glazing, since glass tends to be the part of a building most vulnerable to fire.

Similar strategies are evident in a 3,100-square-foot, three-bedroom California residence built a decade ago on a promontory high above Montecito. Designed by architect Tom Kundig, principal of Seattle-based Olson Kun­dig, the muscular building is in tune with its rugged, high fire-risk setting. Built for a retired couple and now owned by a family whose primary residence is on the East Coast, it has a steel structure, weathering steel cladding, an overhanging steel roof and operable, perforated rolling coil garage-style doors. The latter perform much the same way as the screens in the Australian house, protecting the expansive windows that offer stellar bay views. With the aid of a submersible pump, the pool water could be used for firefighting if necessary.

The house survived last December’s wildfires and the ensuing mudslides unscathed (the fire came within a quarter of a mile of the property). But Kundig is careful not to oversell its capabilities: “It is virtually impossible to design a fire-proof house” or, at least, one you would want to live in, he says. “Our guiding principle was not to provide fuel for the fire.”

Much the same philosophy seems to be behind a house that Palo Alto–based Field Architecture is working on near Healdsburg, in Sonoma County. Although the site did not burn, wildfire resistance has now “been taken on as an explicit objective for all our projects in areas where fire is part of the cycle,” says firm principal Jess Field. Conceived as a series of pavilions, the scheme creates defensible space around the collection of structures with a noncombustible paved area. To prevent embers from accumulating, the individual volumes have a metal skin that folds, wrapping their roofs and wall planes to meet a masonry base. The design also eliminates openings that could permit embers to penetrate the exterior envelope such as vented soffits and unsealed mechanical spaces. Field says that architects working in similar vulnerable settings must accept fire protection as a critical project criterion, “just as we design for other environmental conditions, including earthquakes, wind, and solar orientation.”

Field, Weir, and all the other architects interviewed for this article concur that such design objectives as environmental performance and fire resistance are inextricably linked. To illustrate this concept for potential clients, Kuth and Ranieri have developed a theoretical four-bedroom case study house that integrates green strategies with wildfire preparedness. It incorporates passive systems, such as natural ventilation and thermal mass, with energy-generating PV panels, and battery backup, to provide stable power after a disaster. It also includes rainwater storage and graywater recycling to help conserve potable water while providing a secondary source—along with the swimming pool—for firefighting. They hope it makes the point that the reconstruction effort is “an opportunity not to just rebuild, but to rebuild smarter, more resilient, and ecologically attuned structures.” This goal will become only increasingly urgent as California—and the planet—becomes hotter, drier, and more prone to catching fire.

Case study house to illustrate difference between fire resistance and environmental performance in case of wildfires     A house illustration made of corrugated metal and concrete-and-steel-framed building to protect against wildfires and environmental impact

IMAGES: © FIELD ARCHITECTURE (TOP); KUTH RANIERI (BOTTOM)

RESILIENT RESIDENCE
Kuth Ranieri has developed a theoretical case study house to illustrate the relationship between fire resistance and environmental performance. The concrete-and-steel-framed building, clad in corrugated metal, includes renewable energy, graywater recycling, rainwater storage, and natural ventilation, among other features.


 

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Originally published in Architectural Record
Originally published in April 2018


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