Sometime later this year, homeowners in certain swathes of West Marin are likely to face a new requirement for protecting their homes from fire risk: a five-foot vegetation buffer free of combustible plants.

Dubbed “zone zero,” the plant-free zone will be required at all homes in high- and very-high fire risk areas, according to Jason Weber, Marin’s fire chief. That includes most homes in West Marin. 

The Board of Supervisors last week approved new state maps updating the fire hazard zones in unincorporated Marin, which hadn’t been redrawn since 2007. While fewer areas are highlighted in red—indicating very high risk—many more are now orange, for high risk.

Mr. Weber said homes in both zones face substantial risk, and homeowners in both should take steps to lessen the danger. 

Under Marin’s existing building and fire codes, new homes and homes undergoing major renovations in high-risk zones are already required to use materials designed to reduce the chance of fire, such as non-combustible siding and roofing, fire-safe vents and double-paned windows. 

But later this year, the state is expected to issue a new set of requirements restricting vegetation within five feet of houses in very high-risk areas, Mr. Weber said. Local governments can impose stricter requirements but will not be permitted to reduce them. 

Marin’s building and fire codes currently include general guidance about eliminating combustible vegetation from a property but don’t specify eliminating plants from within five feet of a home.

The details of the state rules have yet to be determined. It’s possible, for example, that potted plants or succulents will be permitted within the buffer. Whatever the new rules include, Marin is likely to apply them to both high- and very-high risk areas, Mr. Weber said.

In some cases, homes on one side of a street might be in very high-risk zones while houses on the other side are just high risk. Having different rules for both wouldn’t make sense, because both face potential wildfire danger, Mr. Weber said.

“These maps tell us one thing in a very simplistic way: We have significant fire hazards here in this county, and we need to make efforts to reduce the risk associated with them,” he said. “We can do that through codes and ordinances that ultimately build a more resilient community.”

The county already inspects homes once every one to three years, depending on their location, and makes home-hardening and defensible-space recommendations to homeowners. If the zone zero rules are approved, those inspections will likely cover the new requirements.

Whether the rules will come with fines is yet to be determined. “We want to educate people first, give them time to be able to make adjustments before we just jump right into enforcement,” Mr. Weber said.

The West Marin fire season peaks in September and October. The risk outlook along the coast looks normal this year but is above normal in inland regions of northern California. 

To search the fire severity zones by address, visit https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-mitigation/fire-hazard-severity-zones