Marin supervisors reverse course on fire-treated wood

Marin residents can keep using wood treated with fire retardant in new construction under an action taken by county supervisors.

The supervisors voted unanimously Jan. 27 to revise a new county code regulating building standards in the wildland-urban interface that they had just adopted in December.

“That code as adopted included a requirement that went beyond state law prohibiting fire-retardant-treated wood in new construction,” said Sarah Jones, director of the Marin County Community Development Agency.

Fire-retardant-treated wood, as defined by the International Building Code, has been impregnated with chemicals by a pressure process or other means.

The supervisors adopted the prohibition at the recommendation of county staff. Marin County Fire Marshal Scott Alber said the problem with fire-retardant-treated wood is ensuring it would be properly maintained. County staff said the fire testing criteria for non-combustible materials is more rigorous than the criteria for fire-retardant-treated wood.

Ryan Pessah, a representative of the Western Wood Preservers Institute, disputed that claim.

At the time, Supervisor Eric Lucan and Supervisor Dennis Rodoni questioned the wisdom of the decision. Rodoni said he was uncomfortable banning a product that is approved for use by the state, and Lucan said he feared the requirement would prompt people to do the construction without pulling permits to avoid complying with the regulation.

The supervisors agreed to approve the new building code on Dec. 9 with the understanding that the decision on fire-retardant-treated wood would be revisited as soon as possible.

The staff report to supervisors stated that limiting the use of fire-retardant-treated wood was initially recommended “because alternative noncombustible exterior covering options are available and provide more robust protection against fire spread.”

Jones said staff reviewed locations where building permits have been issued or new housing planned in the county.

“It was not a surprise that a large majority of our housing sites are in the WUI or fire hazard safety zones,” Jones said, referring to the wildland-urban interface.

The staff report stated that most undeveloped parcels in unincorporated Marin County are located within the wildland-urban interface or fire hazard safety zones, and that “substantially more” residential development is expected than in the last several decades.

Jones appeared to use these facts as a rationale for permitting the continued use of fire-retardant-treated wood.

“This is where the fire marshal’s review of building permits comes in,” she said, “ensuring that whatever the material used, the permit as a whole is adequately accounting for fire safety and community resilience.”

“With this in mind,” Jones said, “we are at this time recommending that the board revert to the state code when it comes to WUI and fire hazard safety zones.”

Rodoni said, “I think giving the residents more options that meet state requirements makes sense at this point.”