Boulder may soon be adding new, more stringent wildfire hardening requirements for homes and other structures, such as less-flammable materials and landscaping, in the outskirts of the city that border on open space.

City officials are looking at changing requirements for both new and existing homes in Boulder’s wildland-urban interface. In those areas, urban development transitions into wild space, so they have a heightened vulnerability to wildfires.

The city is revising its wildfire resilience policies a few years after the destructive Marshall Fire, which leveled more than 1,000 homes in Boulder County, and as scientists have warned that wildfire risks are intensifying due to climate change. Daniel Swain, a climate scientist with the National Center for Atmospheric Research, previously told the Daily Camera that climate change is drying out vegetation and causing longer and more severe fire seasons. In a place like Boulder that is also prone to strong winds, that can be a recipe for disaster.

Although the potential update to Boulder’s policies is in its early stages, staffers have made some initial recommendations for city officials to consider. For example, in new builds in the wildland-urban interface, staffers have recommended requiring non-combustible fencing and other structures within eight feet of a habitable building as well as low-flammability plants within the “defensible space area,” or about five to 30 feet, of a building. Highly flammable plants like junipers would be prohibited in those areas.Lisa Houde, a city planner, said during a presentation at the Dec. 12 City Council study session that fencing can act as a “fuse” to homes, so using non-combustible materials within eight feet of a home can provide a break and keep the home safer from fires.

Staffers also proposed requiring building permits for window and siding replacements across the city, not only in the wildland-urban interface, and also requiring hazard mitigation assessments, fuel management plans or other types of plans during the development review process.

“It’s actually unique that Boulder doesn’t require that already for building permits, and that would be a really great check to ensure that these two very vulnerable parts of the home in the (wildland-urban interface) area are compliant with those fire resistance standards,” said Houde.

One other option staffers have put forth is potentially expanding the wildland-urban interface area. Currently, Boulder Fire-Rescue defines the city’s interface as a very thin strip along the western flank of the city. Houde clarified that an expanded interface area wouldn’t necessarily extend structure hardening requirements beyond the current area, but there could be requirements in the expanded area for managing vegetation and defensible space around structures.

Council members on Dec. 12 were widely supportive of staffers’ suggested requirements and acknowledged the increasing danger wildfires pose to Boulder.

Councilmember Matthew Benjamin said the city needs to “think creatively” and “be bold” in minimizing fire hazards. He said he would like to see brush clearing, tree limbing, non-combustible zones and other requirements applied not only to home remodels, but also at the sale of a home or renewal of a rental license.

Councilmember Mark Wallach concurred, saying, “In light of the extreme gravity of the threat to our community, I would like to see us be as proactive as possible in addressing those kinds of conditions, whether it is for new construction, major renovation, or even existing homes.” He added that, at some point in the future, when the city’s “finances are better,” the city could help support people in making those changes to their homes.

The city attorney said it could be a “fraught” proposition to retroactively enforce wildfire hardening requirements at existing properties, but seven of the nine council members indicated they are interested in exploring the tradeoffs of potentially enforcing these requirements at the time when a property is conveyed.

There are already some regulations for buildings in the wildland-urban interface to mitigate wildfire risks. Under the 2018 International Wildland-Urban Interface Code, or IWUIC, new builds, additions and remodels in interface areas are required to incorporate fire-resistant materials, roof coverings, windows and other features. Building permit applications in the area must also include vegetation management plans.

Boulder has adopted locally-amended versions of the IWUIC regulations, but staffers have pitched the idea that the city could also build fire resiliency into its land use codes. The IWUIC was also updated in 2024, and Boulder will look at adopting an amended version of the 2024 IWUIC next year.

A statewide bill passed in 2023 also established a wildfire resiliency code board, which will set model codes that jurisdictions like Boulder that fall within wildland-urban interface areas have to meet or exceed. The board must circulate its rules and standards by July 1 of next year. Boulder is expected to finish its update of its wildfire hardening policies by the end of 2025.