As Wildfire Seasons Lengthen, Documenting the Profound Effects of Landscaping and Building Materials on Resilience



According to research by the Insurance Institute for Economics and Home Security (IBHS) after the fire, there is a 90 percent chance that a house will be destroyed if embers ignite on the building during wildfire. IBHS executives demonstrated how resilient building materials and landscaping methods can prevent damage during a live fire demonstration during a ULI webinar held for 10 district councilors in June.

As climate change worsens and the frequency of forest fires increases, the western US states are all too familiar with the devastating effects. For example, California experienced six of its biggest fires of all time in 2020, and other western states are preparing for a potentially difficult season given the current drought conditions. Firebreak, a ULI Urban Resilience report, identified trends in industry leaders and members of the industry as they prepare for longer and more dangerous fire seasons, as did local governments such as Sonoma County, California, which recently hosted a ULI Advisory Services Panel.

What can be done to better prepare buildings and developments for these significant risks? Roy Wright, President and CEO of IBHS, along with Daniel Gorham, Research Engineer for the Wildfire Program at IBHS, explored this and other questions in a live wildfire demonstration held exclusively for ULI. The full-length presentation, jointly moderated by ULI Arizona, ULI Austin, ULI Colorado, ULI Houston, ULI Idaho, ULI Orange County / Inland Empire, ULI Sacramento, ULI San Diego-Tijuana, ULI San Francisco, and ULI Utah, is about the Knowledge Finder accessible.

After the demonstration, a panel including Lisa Micheli, President and CEO of Pepperwood Preserve in California, and Dan Richter, Managing Partner of Avimor Development in Idaho, examined how real estate developers and institutions can use wildfire-resistant design methods and how best to align them with the practices Strategies in progress on their projects.

“We are currently in a season where drought and heat continue to make headlines,” said Wright. “That means western communities have to deal with the threat of forest fires.”

The key to understanding successful forest fire preparation, Gorham explained through the demonstration, is understanding that embers are at the heart of the ignition of built environments. Embers are small pieces of burning coal that travel up to a full mile (1.6 km) and float into a house through an open window or HVAC system, eventually igniting and quickly moving from the outside of the house to the eaves spread out, and into the attic. Even indirect embers from getting caught on a plastic fire hose reel or doormat, mulch, or vegetation outside a home can be catastrophic.

“Once it starts, it’s like a freight train,” said Gorham, referring to the cascading effects of fuel availability, embers and wind dynamics. The demonstration included winds of 12 miles per hour (19 km per hour), which he thought would be modest in a real wildfire scenario. In the excerpt from the demonstration, Gorham guides viewers through the difference between fires and other climate hazards due to their binary nature – if an ember ignites, the effects will be far-reaching.

For this reason, the first three feet that surround the perimeter of a property, or what the National Fire Protection Association calls the “immediate zone”, is considered to be the most important defensible space around a structure. The IBHS team proved this point with their demonstration which underscored the importance of fire-resistant materials and defensible space. Gorham guided viewers through the potentially disastrous effects of combustible mulch and alien shrubbery when the test house was on fire and showed the result of the embers transfer. Minimizing risks or potential dangers within a 1.5 m radius of a house helps with this. Tactics like using decorative stones in place of mulch, moisturizing vegetation, and removing plastic materials from the first five feet are simple steps to prevent the embers from igniting.

With new developments in mind, Gorham recommends updating building codes, standards and requirements to require resilient building materials for new buildings. For the large stock of buildings that were not deliberately designed with fire protection in mind, IBHS has designed roadmaps for adapting suburbs to forest fires, which provide instructions for retrofitting the existing suburban housing stock to protect against the spread of embers.

Breakthrough developments such as Avimor, a 9,311 acre master-planned community in the Boise, Idaho foothills, pave the way for proactive forest fire resilience. When completed, Avimor will consist of 12,000 homes and 900,000 square feet (83,600 m²) of commercial real estate. The parish was intentionally designed to retain 6,500 ha (6,500 ha) as native grassland and open space. Avimor is one of the first communities in the country to receive Firewise USA certification as a major new development – a title Richter takes very seriously.

“At Avimor, it is important that we understand that it is not a question of whether we have fire on our pasture, but when,” says Richter, explaining the mindset behind the Firewise community name.

Avimor’s green space serves both as a natural firebreak or barrier and as an important facility for development. The development team’s strategies for preserving the space include using cattle to consume grass and potential fuel for fires. In addition, the HOA Art of Life Director ensures that the fire education is burned into the move-in materials of every new resident. With many of the current Avimor residents moving from California, most understand the sensitivity of the problem and so the market is signaling that this tenant / owner training is well received. ULI’s Urban Resilience program delved into a case study of developing urban resilience with Avimor Development’s forest fire resilience strategies.

Likewise, Pepperwood Preserve, a 1,300-acre research area in Northern California, is focused on advancing the science of fire resistance. The reserve was significantly destroyed by the Tubbs fire in 2017, but a lesson was learned when one of their glass, concrete and steel research buildings was completely intact. During the renovation, the team opted for an ignition-resistant construction of the previous wooden structures: Inside is a wooden frame, but outside is made more resistant with Hardie plate and stucco.

“We’re sticking very closely to defensible space,” Micheli said of Pepperwood’s rebuilding after the fire. “There is rock mulch for the entire five-foot circumference around these buildings.”

Micheli went on to explain the difficult process behind insuring their newly remodeled spaces. Pepperwood’s team went way beyond construction requirements, creating insurance difficulties. “Our primary insurer wouldn’t insure the buildings,” she explained. “We went to 30 vendors and found a policy that was prohibitively expensive.” In the end, only 60 percent of Pepperwood’s construction costs were covered by insurance.

While there is no simple solution to forest fire resilience, Gorham remains confident that education will pave the way for resilient adaptation. “To be trained to understand the embers, to understand the community and the features of the building is so important to understand these fires,” he said.

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