Does Montana Require CO Detectors? Rental Duties and Local Codes

Last verified: August 24, 2026

Montana carbon monoxide detector laws combine a clear rental statute with statewide building-code adoption. MCA 70-24-303(1)(g) requires landlords to install an approved detector in each rental dwelling unit under their control and verify operability at the start of tenancy, and the statute assigns tenants an ongoing duty to keep the device in working order.

Montana also adopts statewide IRC and IBC code editions, so new residential and hotel occupancies with fuel-burning appliance or attached-garage trigger conditions are covered through code enforcement pathways. Montana rulemaking materials reference placement near sleeping areas and UL 2034 alignment for compliant CO detection.

Operators should keep move-in verification records, maintenance logs, permit files, and written notice timelines to support both code compliance and civil enforcement processes.

Quick Safety Summary

CO detector requirements for Montana
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. Montana adopted the classroom rule and then added the half the model code leaves blank. ARM 23.12.601 incorporates the International Fire Code 2021 edition, and a section-by-section read found "915" and "carbon monoxide" occurring zero times in the whole rule against a control of "is not adopted" at 21, so Section 915 stands unamended: a classroom in a Group E occupancy is covered where a condition in Sections 915.1.2 through 915.1.6 exists, and Section 915.2.3 puts the detectors in the classrooms and their signals somewhere: alarm signals go "automatically transmitted to an on-site location that is staffed by school personnel", unless the Group E occupancy has an occupant load of 30 or less. The notable part is the existing building. The model Table 1103.1 leaves Group E blank, and the one Montana amendment reaching Section 1103.9, at (5)(ad), adds Group E classrooms to that table. Subsection (3) makes the code a minimum a local government may exceed and cannot opt out of, subsection (4) applies it to new construction and to existing conditions alike, and 23.12.402(1) puts enforcement in every area of the state. Put those two together and Montana is unusual twice over. Most states that reach a classroom at all reach only a new or altered one; Montana's own amendment to Table 1103.1 carries the whole of Section 915 to a school already standing, and Section 915.2.3 travels with it. So a Montana school built in 1970 with a fuel-fired boiler owes not just detectors in its classrooms but a signal path out of them to a staffed office, on an amendment the state wrote for itself.

Workplaces: Montana 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. Section 915.1.1 stands unamended in Montana and its occupancy list is Group I-1, I-2, I-4 and R plus Group E classrooms, with no Group B, F, M or S. The one Montana amendment reaching Chapter 11 adds Group E classrooms to Table 1103.1 and touches nothing else, so no existing-building route reaches a workplace either. The carbon monoxide provisions Montana writes outside the fire code, MCA 70-24-303(1)(g) and ARM 24.320.301, sit inside the Residential Landlord and Tenant Act and reach a tenancy rather than a place of work.

When Are CO Alarms Required?

Buildings with fuel-burning appliances
Buildings with attached garages
New construction
When building permits are required
Rental dwelling units under landlord control are explicitly covered by MCA 70-24-303(1)(g).

Where to Install CO Alarms

Rulemaking adoption materials describe placement outside each separate sleeping area in the immediate vicinity of bedrooms.
The fire code answers differently for a guest room. IFC 2021 Section 915.2.2, adopted by ARM 23.12.601 without amendment, puts the detection inside the sleeping unit, and allows the corridor only where the room and its attached bathroom hold no fuel-burning appliance and no forced-air furnace serves them.

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

Device Requirements

Listed to UL 2034. A combination carbon monoxide and smoke alarm must be listed to UL 2034 and UL 217 together, under Section R315.1.1 of the residential code Montana adopts. Montana's own rulemaking responses on NEW RULE I reached the same standard, so the state and the model code agree here rather than one deferring to the other.
Primary power from the building wiring where the building is served from a commercial source, with battery backup when that power is interrupted, and permanent wiring carrying no disconnecting switch beyond overcurrent protection, under Section R315.6. Two exceptions: battery operation is permitted in a building without commercial power, and it is permitted for alarms installed because of alterations, repairs or additions rather than new construction.
Read the section number with its edition attached. Montana adopts the 2021 International Residential Code, effective 10 June 2022, and the 2021 International Building Code, effective 11 June 2022, alongside the 2021 International Fire Code at Mont. Admin. R. 23.12.601 effective 11 March 2023. Carbon monoxide alarms are Section R315 in the 2018 and 2021 editions and moved to R311 in the 2024 edition, which gave R315 to sleeping lofts. A reference carried forward without its edition will one day resolve to the wrong subject rather than failing.

Landlord and Tenant Responsibilities

Landlord: Landlords must install approved detectors in each covered rental dwelling unit and verify operability at tenancy start. Provision: 23.12.601(1), (3), (4) and the amendment list at (5), including (5)(ad) on Table 1103.1 and (5)(ae) dropping 1103.5.

Tenant: Tenants must keep required detectors in good working order during occupancy. Provision: 23.12.601(1), (3), (4) and the amendment list at (5), including (5)(ad) on Table 1103.1 and (5)(ae) dropping 1103.5.

Lease documents should define testing, battery replacement, and damage-reporting expectations.
Enforcement of the fire code reaches every acre of the state. ARM 23.12.402(1) makes the Fire Prevention and Investigation Section responsible for administering and enforcing the fire code "in every area of the state of Montana", with local chief fire officials enforcing inside their own jurisdictions; MCA 50-61-114(2) lets a Department of Justice fire inspector enter buildings and premises where no local fire inspection program exists. MCA 50-3-102(4) lets the department sue to enjoin the use of an existing building until it complies.

Full Montana landlord and tenant carbon monoxide duties, with citations

Enforcement

Enforced by: Civil landlord-tenant remedy framework under Title 70, Chapter 24, Part 4.

Enforcement typically occurs:

When a landlord fails to cure written notice regarding required detector conditions within statutory timelines.
During tenancy disputes involving habitability duties tied to detector obligations.

Administrative rule language states these provisions are enforced through civil remedies rather than criminal penalty schedules.

What a Tenant Can Do in Montana

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

"Via general law" means the Montana 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.

"No provision found" is a finding rather than a gap in the research: the chapter that would carry that remedy was read and contains nothing either way. What was read is named beside the row.

Tenant remedies for a defective carbon monoxide alarm in Montana, with the citation or the body of law searched for each.
Rent withholding	No provision foundSearched: MCA Title 70, chapter 24, part 4 (Remedies), the sections listed in the part index from 70-24-401 to 70-24-428, with 70-24-408 essential services and 70-24-409 fire and casualty read in full. There is no counterclaim or pay-into-court section. The position it occupies in Alaska, Iowa, Kansas, Hawaii, Kentucky, Connecticut, Nebraska and Oregon, immediately after essential services, is taken here by fire and casualty at 70-24-409, and nothing elsewhere in part 4 supplies one. What 70-24-406(2) gives instead is damages, so a Montana tenant recovers money afterwards rather than holding it back or lodging it with a court.
Repair and deduct	No provision foundSearched: MCA Title 70, chapter 24, part 4, centred on 70-24-407, the section occupying the model act's repair-and-deduct position, and 70-24-406. 70-24-407 is the trap in this row and it is worth naming. It is captioned damages for minor violations, it uses the threshold the model act uses for repair-and-deduct, a reasonable cost of compliance below one month's rent, and it then provides only that the tenant "may recover damages for the breach under 70-24-406(2)". Montana took the slot and replaced the remedy, so a reader who recognises the threshold and assumes a deduction will be wrong.
Right to end the lease	Via general lawMCA 70-24-406(1)(a). Two speeds, and the fast one is the reason to read this cell. Ordinarily the notice sets termination at not less than 30 days after receipt if the breach is not remedied in 14. But where the noncompliance results in a case of emergency and the landlord fails to remedy within three working days of written notice of the situation and of the tenant's intention to terminate, the tenant may terminate. A recurrence of substantially the same breach within six months drops the notice to at least 14 days.
Notice the tenant must give	Via general lawMCA 70-24-406(1)(a). No waiting period before serving, but the emergency route asks the notice to do something extra: it must state both the situation and the tenant's intention to terminate. A notice that reports a dead alarm without saying what the tenant will do about it leaves the tenant on the ordinary 14 and 30 day track rather than the three-working-day one.
Landlord cure period	Via general law, 14 daysMCA 70-24-406(1)(a). Fourteen days is the ordinary figure and is recorded here. Three working days is the emergency figure, and working days is not the same as days: a notice served on a Thursday before a holiday weekend can leave the landlord until the following Wednesday. A tenant relying on the short route should count the calendar rather than assume 72 hours.

Applies to every row above:The Residential Landlord and Tenant Act of 1977 is a URLTA adoption, and Montana kept the model's architecture while quietly changing what two of its sections do. 70-24-407 sits where the model puts repair-and-deduct and uses the model's threshold, a reasonable cost of compliance under one month's rent, but it hands the tenant damages under 70-24-406(2) rather than a right to spend and deduct. And the slot immediately after essential services, which in eight other states in this matrix holds the counterclaim, holds fire and casualty instead: 70-24-408 is followed directly by 70-24-409. Montana therefore has neither self-help nor a pay-into-court route, and every column below runs through 70-24-406. Text read from an April 2025 capture of archive.legmt.gov carrying the Montana Code Annotated 2023, because every legmt.gov host refuses automated requests.

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

What Montana Requires in Lodging

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

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

Operator duty: ARM 23.12.601 adopts the International Fire Code 2021 edition as Montana's minimum fire protection code, and its amendment list never touches Section 915, so a hotel is a Group R occupancy that takes carbon monoxide detection wherever a fuel-burning appliance, a fuel-burning fireplace, a fuel-burning forced-air furnace or an attached private garage is present. Section 915.2.2 puts the detection inside the guest room unless neither the room nor its attached bathroom holds a fuel-burning appliance and no forced-air furnace serves it. Existing hotels are reached too: Section 1103.9 applies the same conditions to buildings already standing, and Montana's only change to Chapter 11 that touches it, at ARM 23.12.601(5)(ad), adds Group E classrooms to Table 1103.1 rather than removing anything from Group R.

Full Montana hotel and short-term rental requirements

Penalties for Non-Compliance

Montana states the consequence in the lodging chapter rather than in a carbon monoxide provision, which is why a search for one finds nothing. MCA 50-51-106 makes any violation of the hotel, motel and roominghouse chapter, or of a regulation made under it, a misdemeanor punishable by a fine of not less than $50 or more than $100 for a first offense, not less than $75 or more than $200 for a second, and not less than $200 for a third or subsequent one, with imprisonment in the county jail of up to 90 days. A rented dwelling is a different route: the landlord duty at MCA 70-24-303 carries no fine of its own and is enforced by the tenant through the remedies at 70-24-406 and 70-24-407.

MCA 50-51-106 for lodging, read in the Montana Code Annotated 2023. MCA 70-24-303 with 70-24-406 and 70-24-407 for a tenancy, which is a remedy route rather than a penalty.

Additional Notes

This file treats statewide obligations as clearly confirmed for rentals and for new-construction homes and hotels through statewide code adoption.
Operators should preserve civil-remedy documentation, including written notices and cure timelines.

Local Rules That Differ From State Law

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

Helena

Helena is the only jurisdiction in this dataset that asks for the alarm signal to leave the building. Section 13-2-7 of the city code amends the 2021 International Fire Code, and its carbon monoxide amendment does three things. It requires detection in new buildings under Sections 915.1.1 through 915.6 and in existing buildings under Section 1103.9, which keeps the retrofit route alive in a state where the statute reaches rentals rather than buildings generally. Then it adds a sentence with no counterpart anywhere else here: carbon monoxide alarm signals are required to be automatically transmitted as an alarm signal to a supervising station, and must activate the occupant notification system. A detector that sounds in an empty house is worth little; Helena wants the signal to reach somebody who can act on it and to sound through the building at the same time. Two limits on how far to read that. The same section separately amends Section 907.6.6 to require fire alarm systems to be monitored by an approved supervising station under NFPA 72, and that amendment carries express exceptions for single- and multiple-station smoke alarms, for smoke detectors in Group I-3, and for sprinklers in one- and two-family dwellings. The carbon monoxide sentence carries no equivalent exception on its face, which reads as deliberate but is worth confirming with the fire code official before assuming a plug-in alarm in a house has to be monitored. Helena adopts the 2021 edition, so the section numbers are that edition's.

Helena City Code Section 13-2-7, amendments to the 2021 International Fire Code, amending Sections 915.1 and 907.6.6, Chapter 2 Fire Prevention Code Checked 2026-08-10.

What was checked:Montana closes one door and leaves another open, and the single finding below walks through the open one. MCA 50-60-301(2)(a) provides that a county, city or town "may not adopt or enforce a building code that is more stringent than the building code adopted by the department or as required by state law", with one narrow exception for voluntary energy conservation incentives. That is among the tightest limits in this survey: most states let a city go stricter with findings or with state approval, and Montana does not allow it in the building code at all. The fire code is a separate instrument, and Helena's amendment below lives there. Seven municipalities read on 2026-08-10: Billings, Missoula, Bozeman, Great Falls, Livingston, Whitefish and Helena. Five carry nothing, each control-tested. Bozeman's single hit defines major open burning by tonnage of carbon monoxide emitted. Missoula has one that is worth naming without belonging in the table: Section 20.40.135 of the zoning code, governing tourist homes, says they "shall meet all applicable building codes which may include requirements for safe sleeping rooms such as egress windows, smoke detectors and carbon monoxide detectors". That is a signpost to the building code rather than a requirement of its own, which is exactly what 50-60-301 leaves a Montana city able to write. Kalispell, Butte-Silver Bow, Red Lodge and West Yellowstone were not searched, and West Yellowstone and Red Lodge are the two gaps that matter most for lodging.

Local sweep last reviewed 2026-08-10.

Official Sources & References

Montana Code Annotated 70-24-303 landlord duty to maintain premises , 70-24-303(1)(g) (state code, accessed 2026-02-17)
Primary statewide rental-duty text for installation, move-in operability, and tenant maintenance expectations.
Montana Code Annotated 70-20-113 approved detector definition context , 70-20-113 (state code, accessed 2026-02-17)
Definition support for approved detector language referenced by the rental statute.
Montana Administrative Register notice of adoption for NEW RULE I 24.320.301 , Adoption responses on placement and UL 2034 alignment (building code, accessed 2026-02-17)
Rulemaking record used for placement and listing interpretation context.
Montana Department of Labor and Industry, Current Adopted Building Codes , Statewide adoption of current IBC and IRC editions (building code, accessed 2026-02-18)
Official statewide code adoption list supporting new-home and hotel applicability through code pathways.
Mont. Admin. R. 23.12.601, adoption of the International Fire Code (2021 edition) , 23.12.601(1), (3), (4) and the amendment list at (5), including (5)(ad) on Table 1103.1 and (5)(ae) dropping 1103.5 (fire code, accessed 2026-08-09)
Department of Justice, Fire Prevention and Investigation Section. 23.12.601(1) adopts and incorporates by reference the International Fire Code 2021 edition. Amended 2023 MAR p. 212, effective 11 March 2023, so the 2021 edition is current. Read section by section on 2026-08-09: "915" occurs zero times in the whole rule and "carbon monoxide" zero times, against a control of "is not adopted" at 21, so Section 915 is adopted unamended. The only amendment reaching Section 1103.9 is (5)(ad), which adds Group E classrooms to Table 1103.1. Subsection (3) makes the code a minimum that a local government may exceed but not opt out of, and subsection (4) applies it to new construction and to existing conditions.
Mont. Admin. R. 23.12.402, enforcement of Fire Prevention and Investigation Section rules , 23.12.402(1) (fire code, accessed 2026-08-09)
"The FPIS shall administer and enforce in every area of the state of Montana all the provisions of the fire code and rules adopted pursuant thereto." Local chief fire officials enforce inside their own jurisdictions and assist the FPIS. There is no local election and no uncovered area.
Montana Code Annotated 50-3-102 and 50-61-114, fire prevention powers and inspection , 50-3-102(2) and (4), 50-61-102, 50-61-114(2) (state code, accessed 2026-08-09)
50-3-102(2) is the rulemaking power behind ARM 23.12.601, limited only by not conflicting with the Department of Labor and Industry's building regulations. 50-3-102(4) lets the department maintain an action to enjoin the use of all or part of an existing building until it complies. 50-61-114(2) lets a Department of Justice fire inspector enter buildings and premises where no local fire inspection programme exists. Read from Wayback captures; archive.legmt.gov and leg.mt.gov both refused connections on 2026-08-09.

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 Montana statute creates the main landlord CO detector duties?

MCA 70-24-303(1)(g) is the core statewide statute for Montana rental compliance. It requires landlords to install approved carbon monoxide detectors in each rental dwelling unit under their control and verify that devices work at the start of tenancy. The same section also assigns ongoing maintenance responsibility during occupancy. Teams should cite this section directly in lease exhibits and turnover checklists instead of relying on generic safety language. That section-level approach makes disputes easier to resolve.

Which properties are clearly covered statewide in Montana?

Rental dwelling units are clearly covered by MCA 70-24-303(1)(g), and statewide adopted IRC/IBC pathways cover new homes and hotels when trigger conditions are present. The rental statute and building-code pathways work together, so teams should classify each property by occupancy and project status before applying one default rule. Montana records should include a written scope determination that names the governing section, code edition, and decision-maker for each asset. This prevents classification errors during audits and inspections.

Where should detectors be placed and what listing standard is referenced?

Montana rulemaking adoption text references placement outside separate sleeping areas in the immediate vicinity of bedrooms and describes UL 2034 alignment for CO detection performance. Operators should treat these references as implementation guidance alongside statutory approval requirements in the rental law. Installation files should document exact placement, model number, and commissioning date for each unit. That detail supports maintenance planning and lowers disagreement risk during inspections or tenant claims in Montana portfolios.

What happens if a landlord ignores CO detector repairs in Montana?

The cited framework points to civil landlord-tenant remedies rather than a dedicated statewide criminal fine schedule for detector violations. When required corrections are not completed after valid notice, disputes can escalate through remedy pathways that affect tenancy and damages. Operators should therefore treat notice response times as critical compliance controls. Maintain a single timeline showing notice receipt, repair completion, and verification so legal and property teams can prove that corrective duties were handled promptly. In Montana, cite MCA 70-24-303 and related remedy sections in every escalation file.

Do all-electric Montana homes fall outside statewide requirements?

Not always, and the answer depends on occupancy type and governing code path. Montana states its clearest statewide duty for rentals, while broader home scenarios can involve local adoption decisions and project-specific interpretations. Owners should avoid blanket assumptions based only on utility profile and document the exact rule basis for each determination. Reassess that determination if the property use, layout, or adopted local code edition changes. Montana teams should capture that review in annual compliance audits.

How does Montana compare with Wyoming for Mountain-region policy planning?

Montana's requirement shows up in landlord-tenant rental duties, enforced through civil remedies. Across the border, Wyoming's clearest statewide text is in child care rules plus adoption-by-reference code pathways. Regional operators should not deploy one common Mountain-state template without occupancy-level branching. For side-by-side planning, review Wyoming CO detector laws and compare scope triggers, enforcement channels, and documentation controls. Montana program owners should assign separate review checkpoints for both states before policy release.

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