Boulder council adopts updated Wildland-Urban Interface code, approves revised WUI boundary

Boulder City Council on May 15 adopted Ordinance 86 95, updating the city's Wildland-Urban Interface (WUI) regulations to the 2024 edition of the International Wildland-Urban Interface Code with local amendments and unanimously approved a revised map showing the expanded WUI area.

The vote was 8-0 to amend and pass the ordinance; council also voted unanimously to declare the revised WUI area described in staff materials. City staff told council the adopted code focuses on hardening new construction and certain additions to reduce risk from ember-driven spot fires, while a second phase later this year will address landscaping and zoning matters.

The ordinance matters because it changes the building-permit requirements that apply to properties inside the newly drawn WUI boundary and establishes minimum construction and site standards intended to reduce the chance that embers will ignite homes and cause structure-to-structure fire spread. Brad Mueller, director of Planning and Development Services, told council staff used ember‑spread modeling and other fire science to set the boundary and said the code update is the first of several steps planned this year: "This is a fairly narrow topic about the wildfire hardening and specifically breaking it into the two parts of bringing the WUI code' which, as you know, is part of the building code forward tonight," Mueller said.

Key provisions and expected near-term impacts

- New-code scope and map: Staff presented a proposed WUI area that includes roughly 16,000 parcels inside the city limits. The map, staff said, reflects ember-spotting modeling and local conditions on Boulder's western edge. Council approved the revised map by unanimous vote.

- Permits expected: Staff estimated roughly 203 building permits per year will fall inside the revised WUI area under normal activity; about 31 of those would be new-construction permits annually and roughly 72 would be additions or alterations that could trigger specific WUI provisions depending on the work.

- Construction and site rules (high points): The adopted code incorporates ignition-resistant construction requirements for structures inside the WUI and adds local amendments for decks, fences and defensible space. Depending on the ignition-resistance class assigned to a property, requirements include noncombustible gutter materials, screened vents, noncombustible decking surface (with some allowances for combustible framing if enclosed or screened), and a noncombustible zone immediately adjacent to new construction to reduce ember ignition risk. Chief David Lowry of Boulder Fire Rescue summarized the approach: "When we talk about that class 3 ' a lot of what I would refer to as home hardening really drops off in that ignition resistant 3' and that 3 is really looking at more vegetation management and that ember type protection from vegetation catching fire."

- Retroactivity and triggers: The ordinance, as adopted, applies to new construction and to work that expands a building's footprint (for example a new deck or addition). Routine interior remodels and maintenance work do not trigger the WUI hardening provisions. Replacing siding or windows requires a permit, but staff said replacement alone typically triggers only the permit-level requirements for the elements being changed rather than a wholesale retrofit of the whole structure.

- Historic properties and alternative compliance: Staff and the building official said they expect to use existing alternative‑means-and-methods processes when historic properties pose conflicts with prescriptive standards. Rob Adrienne, the city's chief building official, said the code provides room for inspector discretion and negotiated alternative protections for unique circumstances.

Council amendments, debate and next steps

Council accepted staff's recommended local amendments and a late addendum of clarifications. During council deliberations members pressed staff on equity and feasibility issues for multiunit and small‑lot neighborhoods, the potential administrative burden of citywide requirements, and how retroactive measures might be sequenced. Planning staff and the fire chief repeatedly emphasized that the building-code changes are one tool among many in the city's broader wildfire-resilience work.

Council also asked staff to accelerate outreach and to return with more detailed materials for denser and multifamily neighborhoods, and several council members asked staff to research options for incentives and assistance to speed voluntary or subsidized home hardening. Councilmember Wallach said neighborhoods need both regulatory clarity and funding: "We must have a funding mechanism to assist those who need it," Wallach said during deliberations.

At the vote, council also amended the ordinance language so one specific landscaping requirement (Section 6.03.2.5 in the draft ordinance, which had required certain low‑flammability plantings in a 5-to-30-foot band) will not apply to properties in the ordinance's Class 3 areas; staff agreed to revisit landscaping details later in the fall when the land-use code and a city plant list are presented.

Staff told council the WUI code will go into effect in August along with the other adopted international codes, and that staff will return with the land-use (landscaping/zoning) package and additional implementation details this summer and fall. Planning Director Mueller and Lisa Hood, principal planner, said the city will follow up with more detailed guidance for owners, require window/siding permits (a change already implemented this year) to ensure compliance, and continue the detailed home assessment (DHA) program. The city has completed roughly 600 DHAs since November 2023 and expects more to be scheduled as outreach continues.

What council members raised and community concerns

During the public hearing and Q&A councilmembers repeatedly raised the challenge of applying WUI standards in higher‑density, small‑lot neighborhoods where setbacks are short. Planning staff acknowledged the maps and design examples used in outreach were drawn from single‑family scenarios and said staff will add additional illustrations for multifamily and small‑lot contexts. Members of the public who testified urged faster action on retroactive vegetation controls (notably juniper removal) and stronger funding or incentives for homeowners.

Votes at a glance

- Ordinance 86 95: Motion to amend and pass ordinance adopting the 2024 International Wildland-Urban Interface Code with local amendments (including the addendum issued to council before the meeting). Outcome: approved, 8-0. Roll call recorded votes: Council member Benjamin: yes; Mayor Brockett: yes; Mayor Pro Tem Folkerts: yes; Marquis: yes; Council member Shewhart: yes; Council member Speer: yes; Council member Wallach: yes; Council member Weiner: yes.

- Resolution (declaration) adopting the revised WUI area map as recommended in the staff memorandum. Outcome: approved, unanimous.

- Consent agenda (items a-g): approved unanimously at start of meeting.

Implementation, funding and follow-up

Staff noted the city is pursuing a multi-pronged approach: code changes (this ordinance), grants and incentive pilots (the wildfire resilience assistance pilot), outreach and education (expanded DHAs and community workshops), and landscaping/zoning changes this fall. Council members emphasized the need to identify funding to support retrofits and to provide clear, accessible guidance for owners in multifamily and small-lot properties.

Formal records of the ordinance and the revised map and technical guidance will be posted on the city website; staff said they will return in July with a check-in and in September/October with the land-use code changes and proposed plant list.

Ending

The code change represents a step officials said is grounded in research on ember-driven ignitions and aims to reduce the risk that localized fires will spread rapidly between structures. City staff and council members acknowledged the ordinance alone will not eliminate wildfire risk and said they will continue to press a broader suite of actions that include vegetation management, incentives and emergency response planning.