Carbon Monoxide Detector Requirements for Washington Hotels and Short-Term Rentals

Washington set its deadline in statute and let it expire. RCW 19.27.530(1) told the State Building Code Council to require carbon monoxide alarms in all buildings classified as residential occupancies, excluding only owner-occupied single-family homes legally occupied before 26 July 2009, and subsection (2)(a) fixed the schedule: newly constructed residential occupancies by 1 January 2011, all other residential occupancies by 1 January 2013. A hotel is a residential occupancy. There is no grandfathering left to argue about and there has not been for over a decade.

The rules that carry it out live in two chapters, and the one usually cited for hotels is empty. WAC 51-50-0908 has read "Reserved" since 1 July 2016, re-reserved in 2023. The live provisions are WAC 51-50-0915 in the building code and WAC 51-54A-0915 in the fire code, with WAC 51-54A-1103 rewriting Section 1103.9 for buildings already standing. WAC 51-54A-003 adopts the 2021 International Fire Code, effective 1 July 2023.

Short-term rental operators carry a third duty on top. RCW 64.37.020(1)(b) requires the host to represent to each guest that the unit complies with RCW 19.27.530 and the Council's carbon monoxide rules, which turns a building-code obligation into a per-booking statement.

Short-term rental operators face a parallel requirement under RCW 64.37: they must certify to each guest that their unit complies with RCW 19.27.530 and all applicable building code rules for CO alarm installation. Together, these two statutory provisions create a comprehensive CO alarm framework covering both traditional lodging and platform-based short-term rentals, with compliance deadlines now fully elapsed.

Washington's CO alarm mandate applies to all buildings classified as residential occupancies under the state building code (chapter 51-54 WAC), which includes hotels, motels, apartment buildings, condominiums, dormitories, and DSHS-licensed residential treatment facilities. Hotels and motels are explicitly named as covered properties subject to the January 1, 2013 existing-buildings compliance deadline under RCW 19.27.530.

Short-term rentals, defined under RCW 64.37 as dwelling units offered for fewer than 30 consecutive nights that are not hotels, motels, or licensed bed-and-breakfast operations, are covered through the STR operator certification requirement in RCW 64.37.020(1)(b). Owner-occupied single-family residences legally occupied before July 26, 2009 are exempt from the general mandate until the property is sold, but this exemption does not apply to hotels or STRs.

Hotel and motel operators must have alarms installed and working under RCW 19.27.530 and the code sections that carry it, WAC 51-54A-0915 and WAC 51-50-0915 for the requirement and WAC 51-54A-1103 for buildings already standing. Installation is the owner's, and both statutory deadlines, 1 January 2011 for new construction and 1 January 2013 for everything else, passed long ago.

Under RCW 19.27.530(4), in buildings where a tenancy exists, maintenance of CO alarms, including battery replacement, is the responsibility of the tenant or guest, who must maintain the alarm as specified by the manufacturer. For hotels, this means the operator must install and deliver compliant alarms; ongoing battery maintenance during a guest's stay is the guest's responsibility under this provision.

For short-term rental operators, RCW 64.37.020(1)(b) creates an explicit, per-booking compliance certification duty: STR hosts must represent to each guest that the unit is in compliance with RCW 19.27.530 and all rules adopted by the State Building Code Council for CO alarm installation. This certification obligation applies for every stay and creates direct accountability for the host. Failure to maintain compliant alarms or to provide accurate certification can expose STR operators to liability under RCW 64.37 and to building code enforcement actions.

Both hotel operators and STR hosts should check placement against WAC 51-54A-0915 rather than against the building code alone, confirm the UL 2034 listing, and test on a schedule. One thing worth auditing specifically: Washington's fire code lets an existing hotel drop in-room alarms only where the building has a common area carbon monoxide detection system, so a property that took the exemption years ago should confirm that system still exists and still works.

Two chapters carry the requirement and they are written to say the same thing. WAC 51-54A-0915 amends Section 915 of the 2021 International Fire Code, adopted by WAC 51-54A-003 and effective 1 July 2023; WAC 51-50-0915 does the same to the building code. Washington did not take the model text: where the model requires detection in Group I-1, I-2, I-4 and R occupancies, Washington's amendment reads "Group I and R occupancies", which is wider, and adds an exception saying that R-2 occupancies other than college dormitories "are required to install carbon monoxide detectors without exception".

Placement, and Washington amended one of the two rules and not the other. WAC 51-54A-0915 rewrites Section 915.2.1, the dwelling-unit rule, to require detection outside each separate sleeping area in the immediate vicinity of the bedrooms and on each level, with an alarm inside a bedroom that holds a fuel-burning appliance or fireplace. It does not touch Section 915.2.2, the sleeping-unit rule, which therefore stands as the model 2021 text: "Carbon monoxide detection shall be installed in sleeping units", with the outside-the-sleeping-area placement allowed only where the guest room and its attached bathroom contain no fuel-burning appliance and no forced-air furnace serves them. A hotel guest room is a sleeping unit, so 915.2.2 is the rule that governs it and 915.2.1 is the rule for the flats in the same portfolio.

The guest room exemption, new buildings. A sleeping unit in an I or R-1 occupancy, including a hotel, that contains no fuel-burning appliance, no fuel-burning fireplace and no attached garage "need not be provided with carbon monoxide alarms provided that they comply with the exceptions of Section 915.1.4", which turn on whether a communicating opening exists to the fuel-burning equipment, or whether detection has been placed in an approved location between the equipment and the room or on the ceiling of the equipment room.

The guest room exemption, existing buildings, and it is stricter. WAC 51-54A-1103 rewrites Section 1103.9 for existing Group I and Group R occupancies, and its exception 4 requires three things together: the unit is not adjacent to any room containing a fuel-burning appliance, fireplace or attached garage; it is not connected by duct work or ventilation shafts with a supply or return register in the same room to any such room; and the building is provided with a common area carbon monoxide detection system. An operator who removes in-room alarms without installing that common-area system has not taken an exemption. The same section adds that an open parking garage under the building code, or an enclosed one ventilated to Section 404 of the International Mechanical Code, is not an attached garage.

Devices. Single-station alarms listed to UL 2034, installed and maintained to NFPA 72 and the manufacturer's instructions. A detection system is an accepted alternative, to NFPA 72 with detectors listed to UL 2075, and Section 915.5.2 says the code's own locations supersede the ones NFPA 72 gives. Washington moved to NFPA 72 here; NFPA 720 was withdrawn as a standard and does not appear in these sections.

RCW 19.27.530 charges the State Building Code Council with adopting and maintaining CO alarm requirements. Day-to-day enforcement of building code compliance, including CO alarm installation in hotels, falls to local building code officials in each jurisdiction, because RCW 19.27.060 delegates administration and enforcement of the state building code to counties and cities. The office that inspects a hotel is therefore a county or city one rather than a state one, and correction correspondence goes there. Enforcement is typically triggered by permit applications, complaints, or routine inspections.

Compliance with the STR certification requirement under RCW 64.37 is subject to enforcement through local STR permit and licensing programs. The Washington State Department of Health provides public guidance on CO alarm requirements and deadlines but does not serve as the primary enforcement body for building code violations.

Violations of the Washington State Building Code, including failure to install required CO alarms, are subject to enforcement under chapter 19.27 RCW. Local building departments may issue notices of violation, require corrective action, and pursue civil penalties. Short-term rental operators who fail to certify compliance with CO alarm requirements as required by RCW 64.37 may face enforcement under that chapter's provisions. Specific penalty amounts are determined by local jurisdictions under their adopted enforcement ordinances and may vary by city or county; operators should consult the local building authority for jurisdiction-specific schedules.