Marin County, CA Building Safety: Carbon Monoxide Detectors (2026)

14 (Additional Verifications for Final Inspection), adopted by Ordinance No. 3788 in 2023 and amended by Ordinance Nos. 3838 (2025) and 26-002 (2026). 2 into the county's own permit-closure process rather than leaving compliance to chance. The trigger is broad: it applies to existing dwelling units, not just new construction, whenever the unit contains a fuel-fired appliance or fireplace, or has an attached garage with an opening that communicates with the living space. Because the requirement is written as a condition of final inspection on any building permit, pulling a permit for even an unrelated remodel or addition on a qualifying home forces a carbon monoxide alarm check before the county will sign off.

For permits that required plan review, a Community Development Agency building inspector confirms the alarms are installed during the final site inspection. For permits that skipped plan review (minor improvement or maintenance permits), the applicant instead submits a signed affirmative declaration of compliance, which the county retains permanently with the permit record. The alarms themselves must carry State Fire Marshal approval, matching the standard already required statewide, but Marin's contribution is making verification a mandatory gate at permit closure rather than an unenforced expectation.