What Washington Requires for CO Detectors: Placement and Duties

Last verified: August 24, 2026

RCW 19.27.530 sits above the code provisions that carry out Washington carbon monoxide detector requirements, WAC 51-51-0315 among them. The statewide framework applies across covered homes, rentals, and many lodging-related residential occupancies, with trigger conditions tied to fuel-burning sources, fireplaces, attached garages, and code-governed occupancy pathways. Washington code text also addresses placement by sleeping-area proximity and by level of the dwelling, wording the state wrote itself in place of the model code's per-story test.

The statute includes role allocation language, including owner installation obligations and tenant maintenance responsibility in rental contexts identified by the law. Statewide enforcement is primarily carried out by counties and cities under local code administration authority.

Washington operators should preserve section-level citations, installation records, and maintenance history in each property file. Recording local code-administration contacts and inspection timelines for each jurisdiction further supports compliance readiness.

In 60 Seconds

CO detector requirements for Washington
Applies to homes?	Yes
Applies to rentals?	Yes
Applies to hotels/STRs?	Yes
Applies to schools?	Yes, under a condition
Applies to workplaces?	No

Schools and workplaces

Schools: it depends, and the test is one you can apply to the building itself. Washington keeps the classroom limb, widens the institutional one and raises the exception. WAC 51-50-0915 in the building code and WAC 51-54A-0915 in the fire code both write Section 915.1.1 as "Carbon monoxide detection shall be provided in Group I and R occupancies and in classrooms in Group E occupancies in the locations specified in Section 915.2 where any of the conditions in Sections 915.1.2 through 915.1.6 exist", which is wider than the model on the Group I side and identical on Group E. The amendment that matters to a school is at Section 915.2.3: alarm signals are automatically transmitted to an on-site location staffed by school personnel, and Washington raises the model exception from an occupant load of 30 or less to 50 or less, so more small schools sit outside the transmission requirement here than under the model code. RCW 19.27.530(2)(a) then puts a date behind all of it for buildings classified as residential occupancies, and WAC 51-54A-1103 rewrites Section 1103.9 for buildings already standing. The edition behind all of that is the 2021 International Building Code, adopted by reference at WAC 51-50-003 with the rule's own note reading "WSR 22-13-094, 23-12-103, and 23-20-023, s 51-50-003, filed 6/14/22, 6/7/23, and 9/25/23, effective 3/15/24". Still current. The State Building Code Council is considering the 2024 edition with an estimated effective date of 1 November 2026, which is close enough to matter to a project being designed now and is an estimate rather than an adopted date. If it lands, Washington's raised exception is the thing to re-check first: the model moves to a source-based test at Section 915.1.1 and Washington's 50-occupant threshold at 915.2.3 is a state amendment that would have to be re-made against the new text rather than carried across automatically.

Workplaces: Washington places no carbon monoxide detection duty on an office, shop or other workplace. Federal and state occupational rules set an exposure limit for carbon monoxide in air; they do not require a detector to be installed, and this row is about installation. Washington rewrote the occupancy list at Section 915.1.1 and widened it to "Group I and R occupancies and classrooms in Group E occupancies", which is broader than the model on the institutional side and still carries no Group B, F, M or S. Read verbatim in the Cornell mirror of WAC 51-54A-0915 on 2026-08-23. RCW 19.27.530(1) reaches buildings classified as residential occupancies, which an office is not, and RCW 64.37.020(1)(b) runs to short-term rental hosts, so no Washington instrument places a carbon monoxide installation duty on a place of work.

When Are CO Alarms Required?

Buildings with fuel-burning appliances
Buildings with attached garages
New construction
Residential occupancy classifications in adopted code determine whether lodging-type properties fall under covered Group R pathways.
RCW 19.27.530 includes statutory exceptions where no listed carbon monoxide source condition exists.

Where to Install CO Alarms

Outside each separate sleeping area in the immediate vicinity of bedrooms under WAC 51-51-0315.
On each level of the dwelling under WAC 51-51-0315, Section R315.3. Washington states no exclusion at all, so nothing is subtracted from the count.

For detailed placement guidance beyond legal requirements, see where to place carbon monoxide detectors.

Device Requirements

Install alarms in accordance with manufacturer instructions as required by WAC 51-51-0315.
Additional listing and technical details follow adopted Washington code pathways for the applicable occupancy.

Landlord and Tenant Responsibilities

Landlord: Property owners must install required alarms in covered dwellings and rental contexts under RCW 19.27.530. Provision: RCW 19.27.530.

Tenant: Tenant maintenance and replacement responsibilities are assigned by RCW 19.27.530 in covered rental-unit contexts. Provision: RCW 19.27.530.

Washington enforcement and implementation details can vary by local jurisdiction and code-administration practice.
WAC 51-50-0908 has read "Reserved" since 1 July 2016 and was reserved again in 2023. It is the section most often quoted as Washington's carbon monoxide rule and it contains nothing. The live sections are WAC 51-50-0915, WAC 51-54A-0915 and WAC 51-54A-1103.

Full Washington landlord and tenant carbon monoxide duties, with citations

Enforcement

Enforced by: Counties and cities enforcing state building code locally under RCW 19.27.060 and related administration pathways.

Enforcement typically occurs:

During permit and inspection workflow for covered construction and occupancy scenarios.
During local complaint or compliance review when required alarms are missing disabled or non-operational.

What a Tenant Can Do in Washington

When a carbon monoxide alarm stops working in a rented home in Washington, these are the five routes a tenant can take and where each one comes from.

"Via general law" means the Washington carbon monoxide statute itself is silent and the remedy comes from the state's landlord-tenant law instead. The remedy is available even though the alarm rule does not contain it.

Tenant remedies for a defective carbon monoxide alarm in Washington, with the citation or the body of law searched for each.
Rent withholding	Via general lawRCW 59.18.115. Escrow, and gated on government rather than on the tenant. A local government inspector must certify that the conditions exist and make the premises substantially unfit for human habitation, and that inspection is due within a reasonable time not exceeding five days of the tenant's request. The landlord frees the money by producing certification that the repairs were properly completed or by suing; if no action is filed within sixty days, the tenant may ask the court to release the funds.
Repair and deduct	Via general lawRCW 59.18.100. Two routes with different ceilings. The contractor route caps each repair at one month's rent and the twelve-month total at two months'. The self-help route, available where the work does not legally require a licensed or registered person, caps each repair at half a month's rent and the twelve-month total at one month's. A tenant may also give the landlord a good faith estimate of the cost before proceeding.
Right to end the lease	Via general lawRCW 59.18.090. Once the landlord misses the deadline in 59.18.070, the tenant may terminate on written notice and quit with no further obligation under the agreement, or sue, or arbitrate where the parties agreed to it. Termination here needs no court permission, which puts Washington ahead of Michigan and Massachusetts, where ending the tenancy over conditions means abandonment and a constructive-eviction argument afterwards.
Notice the tenant must give	Via general lawRCW 59.18.070. Written notice to the landlord starts everything, and no waiting period attaches to the notice itself. What the notice says matters more here than in most states, because the landlord's deadline is set by which category the defect falls into rather than by a single clock, so a notice that describes the hazard rather than the appliance is what earns the shorter deadline.
Landlord cure period	Via general law, 10 daysRCW 59.18.070. Ten days is the residual tier, "all other cases", and it is recorded here because it applies unless a faster one is triggered. Two faster tiers sit above it: 72 hours where the tenant loses a refrigerator, a range and oven, or a major plumbing fixture, and 24 hours where the defect removes hot or cold water, heat or electricity, or is imminently hazardous to life. The statute never names carbon monoxide, so which tier a dead alarm falls into is an argument about that last phrase rather than a settled reading. The argument has a shape worth giving a tenant, because the gap between the tiers is nine days on a defect that kills. An alarm is not itself hazardous. What is hazardous is gas, and the alarm is the thing that would tell you about it. So the two situations separate. Where a fuel-burning appliance is suspect, or anyone has symptoms, or a neighbouring unit has already had a reading, what is being reported is a live carbon monoxide risk with no working detection, and that is what "imminently hazardous to life" is for. Where the alarm has expired in a unit with nothing else wrong, the residual ten-day tier is the honest reading. Which is why the notice matters more here than anywhere else in this row. 59.18.070 asks for "the nature of the defective condition", and a notice saying the boiler smells and no alarm works describes a different condition from one saying the alarm is out of date. No authority settles it. A Washington appellate decision, an Attorney General opinion or a published local housing authority position would, and none was found: searches returned the statute and secondary guides restating it. Recorded as unresolved rather than resolved by inference.

Applies to every row above:The Residential Landlord-Tenant Act is not a URLTA adoption. It does not call itself uniform, its sections run on Washington's own numbering rather than the model act's article-and-sequence scheme, and its habitability trigger reads "substantially endangers or impairs the health or safety" instead of URLTA's "materially affecting health and safety". RCW 19.27.530 puts the carbon monoxide duty on the landlord at move-in and hands maintenance, batteries included, to the tenant, and it creates no remedy, so every column comes from Chapter 59.18. One condition governs the whole row: under RCW 59.18.080 the tenant must be current in rent, including any utilities the lease assigns them, before exercising any remedy in the chapter. Washington is therefore a pay-to-play state in the same sense as Texas, and a tenant who stops paying to force a repair loses the toolkit.

Remedies last checked 2026-08-03. Compare Washington with the other states.

What Washington Requires in Lodging

The Washington carbon monoxide requirement reaches hotels and short-term rentals.

Hotels already standing: covered too. The Washington requirement reaches an existing hotel and not only one being built.

Operator duty: RCW 19.27.530(2)(a) required every building classified as a residential occupancy to carry carbon monoxide alarms by 1 January 2013, and a hotel is one, so the deadline for existing stock passed over a decade ago. WAC 51-54A-0915 in the fire code and WAC 51-50-0915 in the building code both amend Section 915 to reach "Group I and R occupancies", wider than the model text, and WAC 51-54A-1103 rewrites Section 1103.9 for buildings already standing. A guest room may go without its own alarm only under the exceptions, and in an existing hotel those require the building to have a common area carbon monoxide detection system.

Full Washington hotel and short-term rental requirements

Penalties for Non-Compliance

RCW 19.27.530 does not provide one statewide stand-alone fine table for carbon monoxide alarm noncompliance in the cited section text.

RCW 19.27.530 with local enforcement administration under RCW 19.27.060.

Additional Notes

Washington compliance files should keep RCW and WAC citations together with occupancy classification records.
Local jurisdictions may have process differences for inspection scheduling and correction notices.

Local Rules That Differ From State Law

At least one Washington municipality sets CO requirements that go beyond the statewide rule. Where your property sits decides which applies, and the stricter one governs.

Seattle

Seattle attaches four duties to the alarm that the state standard does not carry, and three of them are about the moment a tenancy turns over. Section 22.206.160.B.5 of the Housing and Building Maintenance Code makes the owner install the alarms and then test them when each housing unit becomes vacant. Paragraph 6 requires all needed repairs, or replacement with working devices, before the unit is reoccupied. Paragraph 7 is the one nothing else in this dataset asks for: the owner must instruct the tenant in the purpose, operation and maintenance of the detectors and alarms, and have the tenant sign a statement of understanding. Section 22.206.170.H then puts a matching duty on the tenant, to test to the manufacturer's recommendations and keep the alarms working, batteries included. The fourth addition is that somebody checks. Seattle runs a Rental Registration and Inspection programme, and Section 22.214.050 lists what the inspection and certificate of compliance must cover; item 16 is the carbon monoxide requirement in 22.206.160.B.5, sitting beside the smoke detector requirement at item 15. A state placement rule enforced only after something goes wrong becomes, in Seattle, a periodic inspection item on a registered rental. Short lets are covered separately at Section 6.600.070.8, which makes a short-term rental operator comply with RCW 19.27.530 by ensuring working smoke detectors, carbon monoxide alarms in every bedroom and on all habitable floors, and a maintained and charged fire extinguisher.

Seattle Municipal Code Sections 22.206.160.B.5 to B.7 and 22.206.170.H, with the inspection checklist at 22.214.050 item 16 and short-term rental duties at 6.600.070.8 Checked 2026-08-10.

Chelan

Chelan inspects before the first licence and then makes the operator certify every year after. Section 5.15.080 sets what an application for a short-term rental operating licence must show, and it splits the job in two: before the initial licence the city performs a life-safety inspection itself, and thereafter each annual renewal has to arrive with a completed self-certification checklist for health and safety, on the administrator's own form, covering fire extinguishers, smoke alarms, carbon monoxide detectors and egress. The pattern is worth noticing because it is cheaper than annual inspection and harder to ignore than a one-off: the city sees the property once and then holds a signed statement for every year of operation after that.

Chelan Municipal Code Section 5.15.080, short-term rental operating licence, application requirements and criteria for approval Checked 2026-08-10.

What was checked:Seven jurisdictions read on 2026-08-10: Seattle, Spokane County, Chelan, Walla Walla County, Long Beach, Liberty Lake and Orting. Seattle and Chelan are below. The other five carry nothing, each control-tested against terms their own indexes return. Neither entry below changes where an alarm goes, and the distinction matters. Washington's placement standard comes from RCW 19.27.530 and WAC 51-51-0315, and Seattle's own wording tracks it: outside each sleeping room, on each level, and inside a sleeping room holding a fuel-burning appliance or fireplace. What the two cities add is everything around the device, which is where a maintenance code and a licence can go and a construction code cannot. Tacoma, Spokane city, Vancouver, Bellingham and Leavenworth are on none of the working hosts and were not reached.

Local sweep last reviewed 2026-08-10.

Official Sources & References

Revised Code of Washington chapter 59.18, Residential Landlord-Tenant Act, sections 59.18.060 and 59.18.070 , 59.18.060 landlord duties; 59.18.070 notice contents and the three remedial deadlines (state code, accessed 2026-08-20)
The chapter the whole remedy analysis on this page argues from, and until 2026-08-20 it appeared in no source entry. Read from FindLaw because app.leg.wa.gov refuses connections from this network and the Internet Archive was returning 503. Two things are worth having verbatim. 59.18.070 sets the deadlines the page describes: "not more than twenty-four hours, where the defective condition deprives the tenant of hot or cold water, heat, or electricity, or is imminently hazardous to life"; "not more than seventy-two hours" for a refrigerator, range and oven, or a major plumbing fixture; and "not more than ten days in all other cases". The same section requires the notice to specify "the premises involved, the name of the owner, if known, and the nature of the defective condition", which is why describing the hazard rather than naming the appliance is what earns the shorter deadline. And 59.18.060 does not mention carbon monoxide, measured rather than assumed. The duty a dead alarm reaches is subsection (1), maintain the premises to substantially comply with any applicable code "if such condition endangers or impairs the health or safety of the tenant". So the chain runs WAC 51-51-0315 for the requirement, 59.18.060(1) to make complying with it a tenancy duty, and 59.18.070 for the clock.
Revised Code of Washington section 19.27.530 , 19.27.530 (state code, accessed 2026-02-17)
Primary statewide statutory source for requirements, exceptions, and rental responsibility language.
Washington Administrative Code section 51-51-0315 , Sections R315.2 and R315.3 of the 2021 Washington State Residential Code, the edition in force after the Building Code Council pushed the 2021 group's start from 1 July 2023 to 29 October 2023. R315.2 is the trigger, split into R315.2.1 for new construction and R315.2.2 for alterations, repairs and additions; R315.3 is placement, and Washington's version of it asks for an alarm outside each separate sleeping area in the immediate vicinity of the bedrooms and on each level of the dwelling, the second half being the state's own addition to the model text. Read the number with the edition attached. Carbon monoxide alarms are R315 in the 2018 and 2021 International Residential Code and moved to R311 in the 2024 edition, which gave R315 to sleeping lofts, so a reference carried forward without its edition will one day resolve to the wrong subject rather than failing. (building code, accessed 2026-08-20)
Placement and installation framework for residential carbon monoxide alarms. Re-read 2026-08-20 from Cornell LII, which reproduces the WAC verbatim, because app.leg.wa.gov refused connections from this network. R315.3 reads "outside of each separate sleeping area in the immediate vicinity of the bedrooms and on each level of the dwelling and in accordance with the manufacturer's recommendations", and R315.2.1 carries the same wording for new construction while R315.2.2 sends existing dwellings to R315.2.1. There is no exclusion anywhere in the section. The contrast sits inside Washington's own book: R314.3, the smoke alarm provision, locates alarms "on each additional story of the dwelling, including basements and habitable attics but not including crawl spaces and uninhabitable attics". That list belongs to smoke alarms and does not reach R315, so a summary that applies it to carbon monoxide placement in Washington is reading the wrong section, as is one that keeps the model per-story test the state replaced with per-level.
Washington State Fire Code, WAC 51-54A-003, 51-54A-0915 and 51-54A-1103 , 51-54A-003 adoption; 915.1.1 with its exceptions; 915.2.1 as amended and 915.2.2 left unamended; 1103.9 with exceptions 1 through 5 (fire code, accessed 2026-08-09)
WAC 51-54A-003 adopts the 2021 International Fire Code by reference, amended WSR 22-13-093 effective 1 July 2023. WAC 51-54A-0915 rewrites Section 915.1.1 to reach "Group I and R occupancies", which is wider than the model's Group I-1, I-2 and I-4, and makes detectors mandatory without exception in R-2 occupancies other than college dormitories. The sections it rewrites inside 915 are 915.1.1, 915.2.1, 915.2.3, 915.5.1, 915.5.2 and 915.6. 915.2.2 is not among them, so the sleeping-unit placement rule stands as model 2021 text and is the one that governs a guest room. WAC 51-54A-1103 rewrites Section 1103.9 for existing Group I and Group R occupancies, with the hotel exemption at exception 4 requiring three conditions together, including that "the building is provided with a common area carbon monoxide detection system". Read from Cornell LII on 2026-08-09 because app.leg.wa.gov refused connections.
Washington State Building Code Council carbon monoxide fact sheet , Public guidance summary (agency guidance, accessed 2026-02-17)
Supplemental agency guidance aligned to RCW and WAC references.

Disclaimer: This page explains the law as it stood on August 24, 2026. It is general information, not legal advice, and reading it creates no attorney-client relationship. Requirements vary by city, county and building type, and statutes and codes are amended: confirm the current text with the issuing authority before acting on it. Each requirement here cites the instrument it comes from, so you can check it at source.

Frequently Asked Questions

Which Washington law is the main carbon monoxide requirement?

RCW 19.27.530 leads, supported by placement language in WAC 51-51-0315. This combination sets the requirement framework for covered homes, rentals, and certain lodging-related occupancies. Owners should not rely on one summary sentence because exceptions and role allocation details are section-specific. Washington property files should keep RCW and WAC citations in the same packet so installation and maintenance decisions remain traceable during inspections. Include local enforcement contact details in that packet.

Where must carbon monoxide alarms go in a Washington home?

WAC 51-51-0315 places alarms outside sleeping areas in immediate bedroom vicinity and on each level of the dwelling. Washington replaced the model per-story test with its own, so a basement or a split-level half-floor is counted without an argument about whether it is a story. Placement should be documented room by room and matched to the locally enforced code edition. Teams should keep as-built location records and device details for each unit. Washington compliance outcomes are stronger when placement evidence and section citations are preserved together for audit and enforcement review.

How are landlord and tenant responsibilities split in Washington?

RCW 19.27.530 assigns owner installation duties in covered contexts and includes tenant maintenance and replacement responsibilities in rental scenarios identified by the statute. This means compliance workflows should include both owner and occupant action steps, not only installation checklists. Lease packets should identify reporting channels for non-operational devices and timelines for correction. Washington operators should keep notices and repairs in a dated log tied to the governing section. This log should include completion date and verifier.

What penalty table does Washington list for noncompliance?

The cited RCW 19.27.530 section does not present one stand-alone statewide fine table specific to carbon monoxide alarm violations. Even without a dedicated fine schedule in that section, local enforcement and liability exposure can still be significant when required alarms are missing or disabled. Teams should prioritize prompt correction and preserve proof of remediation. Washington compliance notices should cite RCW 19.27.530 and local enforcement instructions. Keep each notice linked to the property compliance timeline.

Is an all-electric Washington home exempt from the alarm requirement?

Not automatically. Washington scope depends on statutory exceptions, occupancy classification, and local interpretation of risk conditions in the adopted code framework. Owners should avoid broad assumptions and verify exemption logic with the local authority having jurisdiction before finalizing status. Written exemption records are important for turnover, insurance, and incident review. Washington files should store the exact section language used to justify each exemption. Include the approving authority and decision date.

How quickly must a Washington landlord fix a broken carbon monoxide alarm?

Washington gives three deadlines at RCW 59.18.070 and a dead alarm is not obviously in any of them, which is worth knowing before you write. The landlord must begin work within twenty-four hours where the defect removes hot or cold water, heat or electricity or "is imminently hazardous to life", within seventy-two hours for a refrigerator, a range and oven or a major plumbing fixture, and within ten days in all other cases. The statute never mentions carbon monoxide. An alarm is not itself hazardous; gas is, and the alarm is what would tell you about it. So a report of a suspect appliance, symptoms, or a reading in a neighbouring unit with no working detection is arguably the twenty-four hour tier, while an alarm that has quietly expired in a unit with nothing else wrong is the ten-day one. The section requires the notice to state "the nature of the defective condition", so what you write decides which clock you are asking for.

Practical CO Detector Guides

Beyond legal requirements, these guides help you choose, install, and maintain CO alarms:

Where to place carbon monoxide detectors, room-by-room placement recommendations
CO detector beeping patterns, what different alarms mean
What to do if your detector goes off, emergency response checklist
CO resources and links, official agencies and safety information