Seattle, WA Building Safety: Carbon Monoxide Detectors (2026)
Key Facts
- Placement required
- Outside each sleeping room, every level
- Extra placement
- Inside bedrooms with fuel-burning appliance/fireplace
- Test trigger
- Every time a unit becomes vacant
- Enforcing agency
- Seattle Dept. of Construction and Inspections
- Penalty, days 1-10
- $150/day per unit
- Penalty, day 11+
- $500/day per unit
Summary
Owners of Seattle rental buildings must install carbon monoxide alarms outside each sleeping room, on every level of the dwelling, and inside any bedroom with a fuel-burning appliance or fireplace. The duty comes from the Housing and Building Maintenance Code, SMC 22.206.160.B.5, and applies on every change of tenancy.
5.Install carbon monoxide alarms outside each sleeping room and on each level of the dwelling unit, and inside any sleeping room that contains a fuel-burning appliance or fireplace, and test carbon monoxide alarms when each housing unit becomes vacant;
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Municipal Code: Supplement 44 Update 1).
Full Breakdown
206 of the Seattle Municipal Code, imposes specific maintenance duties on owners of buildings containing rented housing units, separate from and layered on top of the statewide Residential Landlord-Tenant Act. 5 requires owners to install carbon monoxide alarms outside each sleeping room and on each level of the dwelling unit, and inside any sleeping room that contains a fuel-burning appliance or fireplace, and to test those alarms every time a housing unit becomes vacant between tenancies. 7 requires owners to instruct incoming tenants on the purpose, operation, and maintenance of the alarms and to have the tenant sign a statement of understanding.
H to test the alarms according to the manufacturer's instructions and keep them working, including replacing batteries. 220 after an inspection or investigation, with the property owner given a compliance deadline before penalties accrue. B, including the carbon monoxide alarm requirement, apply to any building that contains rented housing units.
Violations & Fines
Failing to install or maintain required carbon monoxide alarms under SMC 22.206.160.B.5 is a violation of Chapter 22.206, enforced by SDCI. SMC 22.206.280.A.1 sets a cumulative civil penalty of $150 per day per housing unit in violation for the first ten days, rising to $500 per day per unit after that, plus inspection charges, and a repeat violator within seven years can face a gross misdemeanor charge under SMC 22.206.290.
Frequently Asked Questions
Are carbon monoxide alarms required in Seattle rentals?
Who is responsible for maintaining CO alarms after move-in, the landlord or tenant?
What happens if a Seattle landlord doesn't install required CO alarms?
Sources & Official References
Other rules in Seattle
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