CO Detector Requirements for New Hampshire Rentals
A property manager takes over a six-unit building in Manchester and discovers every CO alarm has expired. Under New Hampshire landlord carbon monoxide detector requirements, those devices must be replaced and operational before tenants take possession, and the penalties for noncompliance are not modest. RSA 153:10-a sets out the statewide framework, requiring CO alarms in dwellings with fuel-burning appliances, attached garages, or post-2010 construction. What separates New Hampshire from many states is a two-tier penalty structure: individuals face up to $1,000 per offense, while non-natural persons, such as LLCs and property management companies, face up to $20,000. This page explains what New Hampshire rental operators and tenants actually owe under RSA 153:10-a, the placement rules aligned with NFPA 720, and the enforcement path through the State Fire Marshal.
Last verified: August 24, 2026
Key Takeaways
- New Hampshire requires CO alarms in dwellings with a fuel-burning appliance, attached garage, or construction/substantial rehabilitation after January 1, 2010.
- Landlords must provide, install, and maintain CO alarms in suitable condition under RSA 153:10-a.
- Tenants may not remove batteries, disconnect power, tamper with, or disable CO alarms.
- RSA 153:10-a states no placement rule; it names NFPA 720, a standard withdrawn in 2018. In practice: outside each sleeping area, on every occupiable level including basements, and inside bedrooms with a fuel-burning appliance or attached bathroom containing one.
- Penalties are steep, up to $1,000 per offense for individuals and up to $20,000 per offense for non-natural persons (LLCs, corporations) under RSA 153:24.
- Hotels and motels are covered under the multi-unit dwelling and rental definitions.
Legal Summary
RSA 153:10-a settles the New Hampshire rental question end to end: the trigger, the placement and the person who carries the duty. The statute is triggered when a dwelling contains a combustion-fuel-burning appliance, has an attached garage, or was built or substantially rehabilitated after January 1, 2010. A dwelling is exempt only when it has neither an attached garage nor a combustion-fuel appliance, a narrow exception that leaves most rental properties squarely within the law's scope.
Definitions in RSA 153:1 expand the reach by including multi-unit dwellings, hotels, and motels in the statutory framework. That means a bed-and-breakfast or seasonal motel with gas heating falls under the same CO alarm requirements as an apartment building. For device and placement standards the law points away from itself, to NFPA 720, and that is the detail landlords most often get wrong here. It is covered in full below.
Enforcement authority sits with the State Fire Marshal under RSA 153:10-a, with delegation to municipal fire officials where local capacity exists. The penalty provisions in RSA 153:24, read together with RSA 651:2 sentencing guidelines, create one of the sharpest individual-versus-entity penalty disparities in any state CO alarm statute. For rental operators structured as LLCs or corporations, that distinction directly affects financial exposure.
Who Rental Rules Cover
New Hampshire's CO alarm law covers any dwelling that meets a trigger condition, which means most rental properties are included. Leased single-family homes with gas furnaces, multifamily buildings with attached parking structures, and apartments with fuel-burning water heaters all fall within RSA 153:10-a. The statute does not exempt small landlords or older buildings from its scope.
The definitions in RSA 153:1 extend coverage to hotels, motels, and other multi-unit dwellings. That inclusion is significant because transient-occupancy operators, not just traditional landlords, must comply with the same CO alarm installation and maintenance standards. Short-term rental operators using fuel-burning appliances or attached garages should treat the statute as applicable unless local counsel advises otherwise. The only dwelling exemption is the narrow case where the unit has neither a combustion-fuel appliance nor an attached garage, and was not built or substantially rehabilitated after the 2010 threshold.
Landlord Responsibilities
Under RSA 153:10-a, the landlord's duty in New Hampshire is explicit: provide, install, and maintain CO alarms in suitable condition. That three-part obligation means the landlord cannot simply hand a tenant an uninstalled device or defer installation until after occupancy begins. The alarm must be in place, functional, and properly located before the tenant takes possession.
The maintenance duty extends throughout the tenancy. New Hampshire does not shift day-to-day upkeep responsibility to the tenant the way some states do. The landlord must keep the device in suitable condition, which includes replacing expired alarms, addressing malfunctions, and ensuring the unit remains compliant as equipment ages. For properties built or substantially rehabilitated after January 1, 2010, the statute also requires hardwired alarms with battery backup and interconnection when multiple alarms are installed, meaning the landlord's installation duty is more demanding in newer buildings.
Practically, New Hampshire landlords should build CO alarm verification into every lease-turn checklist, maintain records of device installation dates and model numbers, and establish a documented process for responding to tenant reports of alarm issues. The penalty exposure for non-natural persons, up to $20,000 per offense, makes compliance documentation especially important for property management companies and LLC-held portfolios. A missing alarm in a single unit could create a five-figure liability event for an entity owner.
Tenant Responsibilities
New Hampshire defines the tenant's CO alarm role in restrictive terms. Under RSA 153:10-a, a tenant may not remove batteries from a CO alarm, disconnect power to the device, or tamper with or disable it in any way. The statute does not assign tenants affirmative maintenance duties such as testing or battery replacement, instead, it focuses on prohibiting interference.
That prohibition matters practically. A tenant who removes a CO alarm battery to stop a low-battery chirp, or who disconnects a hardwired device during a renovation project, is violating state law. The safer course for tenants is to notify the landlord or property manager immediately when a device malfunctions, chirps, or appears to need service, rather than taking self-help action that could constitute tampering.
For landlords, the tenant's prohibition against interference is a useful lease-addendum point. Documenting the statutory restriction in the lease or a CO alarm addendum creates a written record that the tenant was informed of the legal limits on device removal and tampering.
Installation, Placement, and Device Rules
RSA 153:10-a states no placement locations at all. Read it and there is nothing to place: paragraph I requires carbon monoxide detection devices in each multi-unit dwelling and rental unit "in accordance with the NFPA 720 Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment", and every location New Hampshire enforces comes from that standard rather than from the statute.
There is a complication in that sentence, and it is the thing worth knowing about New Hampshire. NFPA withdrew NFPA 720 in August 2018, folding carbon monoxide alarms into Chapter 29 of NFPA 72. The statute was last amended in 2011 and still names the withdrawn standard, so the instrument New Hampshire law points at no longer exists as a document. What fire departments in the state actually cite is the successor: Portsmouth's fire department gives the placement rule as NFPA 72 29.7.1.1, on every occupiable level of a dwelling unit, including basements, excluding attics and crawl spaces, and Hanover states the same level rule without the exclusion. Nothing makes the successor text apply automatically, so a property with money riding on the answer should put the question to the state fire marshal or the local enforcement authority rather than to a summary.
So the working answer is alarms outside each sleeping area in the immediate vicinity of bedrooms, on every occupiable level including basements, and inside any bedroom that contains a fuel-burning appliance or has an attached bathroom with one. Note what the exclusion does and does not say: it is attics and crawl spaces, not uninhabitable attics. The "uninhabitable" qualifier belongs to the smoke alarm sections of the residential codes and gets copied onto carbon monoxide placement summaries where it does not belong.
The bedroom-interior placement rule is a notable detail. Many states require alarms only in hallways near bedrooms, but New Hampshire adds an in-bedroom requirement when a fuel-burning appliance is present in the sleeping space or its directly connected bathroom. That additional location matters for units with gas fireplaces in master bedrooms or in-suite gas water heaters.
For new construction and substantial rehabilitation after January 1, 2010, devices must be hardwired with battery backup. When multiple alarms are required, they must be interconnected. Combination smoke/CO alarms are permitted when they satisfy both smoke and CO alarm standards independently.
Move-In, Testing, Maintenance, and Notice
The New Hampshire rental CO alarm workflow begins before the tenant takes possession. The landlord must have compliant alarms installed and operational at every required location before occupancy starts. For post-2010 construction, that means hardwired, battery-backed, and interconnected devices, not plug-in or battery-only units.
During tenancy, the landlord retains the maintenance obligation. The statute's "maintain in suitable condition" language means the owner should schedule periodic alarm checks, replace devices before their manufacturer-specified end-of-life date, and respond promptly when a tenant reports a malfunction. Property managers should keep written records of inspection dates, replacement schedules, and any tenant communications about device issues.
New Hampshire does not specify a CO-alarm-specific entry provision in RSA 153:10-a. Standard landlord-tenant entry rules under New Hampshire law apply. Landlords should provide appropriate notice before entering to inspect, test, or replace CO devices. For multi-unit buildings, coordinating alarm testing with annual fire-safety inspections is a practical way to document compliance across all units in a single service visit.
Enforcement, Complaints, and Tenant Remedies
Enforcement of New Hampshire's CO alarm law falls to the State Fire Marshal, who may act directly or delegate authority to municipal fire officials under RSA 153:10-a. That two-tier enforcement model means a complaint could be handled by the local fire department in towns with delegated authority, or escalated to the state level where local capacity is limited.
For tenants, the first practical step when a required alarm is missing or non-functional is written notice to the landlord. If the landlord fails to act, tenants can contact the local fire department or the State Fire Marshal's office to report the deficiency. Local ordinances may impose additional inspection or complaint-resolution procedures beyond the state baseline. Tenants should document all communications and retain copies of any written requests for alarm repair or replacement.
What a Tenant Can Do in New Hampshire
When a carbon monoxide alarm stops working in a rented home in New Hampshire, these are the five routes a tenant can take and where each one comes from.
"Via general law" means the New Hampshire 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.
| Rent withholding | Via general lawRSA 540:13-d; RSA 540:13, III. A defence with a pay-into-court, not a right to stop paying. Under 540:13-d no action for possession based on nonpayment may be maintained where the premises substantially violate the RSA 48-A standards and the violation materially affects habitability, but the tenant carries four conditions and an unusual burden: they must prove by clear and convincing evidence that they gave notice while not in arrears, the landlord must have failed to correct within 14 days or, in an emergency, as promptly as conditions require, the violation must not be theirs, and repairs must not have been blocked by extreme weather or by the tenant's own refusal of access. The court may then continue the case up to a month, and 540:13-d II requires all withheld and accruing rent to be paid into court during it; if the landlord fixes the defect the court apportions that money between the fair rental value of the defective premises and damages for breach of the warranty of habitability, and if the landlord does not, the tenant takes judgment and the whole deposit back. There is a second, smaller route that does not depend on RSA 48-A at all: under 540:13, III, where the landlord adds a claim for unpaid rent to the possession action, the court must consider any defence, claim or counterclaim that offsets what is owed, and a counterclaim exceeding the arrears wins the tenant both possession and a money judgment, capped at $1,500. |
|---|---|
| Repair and deduct | No provision foundSearched: RSA title LV chapter 540, Actions Against Tenants, read in full from the Legislature's merged chapter page, together with RSA chapter 48-A, Housing Standards, and RSA 153:10-a. New Hampshire has no self-help repair remedy. The word deduct appears zero times in the whole of chapter 540, against 69 occurrences of landlord and 152 of tenant across roughly 59,000 characters, which is the control on this negative. What a tenant recovers instead is money after the fact, through the 540:13-d apportionment or the 540:13, III counterclaim, and in both cases a court decides the amount. The route worth knowing about is not statutory at all: RSA 153:10-a VII gives the fire marshal or the delegated municipal authority the power to serve a notice of violation on the owner specifying a time limit for correction, so the practical move for a New Hampshire tenant with a dead alarm is to get an inspector to write that letter rather than to buy an alarm and bill for it. |
| Right to end the lease | No provision foundSearched: RSA title LV chapter 540, Actions Against Tenants, sections 540:1 through 540:29 read in full, including 540:11-a, 540:11-b, 540:13, 540:13-a and 540:13-d. Chapter 540 is written around the landlord's action for possession rather than around the tenant's exit, and both of its tenant terminations turn on who the tenant is rather than on the state of the unit: 540:11-a for a member of the armed services or national guard called to active duty, and 540:11-b, effective January 2025, for a victim of domestic violence. Neither is this column. 540:13-d is a shield and not a door; it defeats an eviction and apportions rent, and the tenancy survives it. A New Hampshire tenant who wants out over a defect argues constructive eviction and breach of the implied warranty of habitability, which is judge-made here rather than statutory, from Kline v. Burns, 111 N.H. 87, 276 A.2d 248, decided by the Supreme Court of New Hampshire in April 1971. That citation was confirmed through CourtListener's search index; the opinion text was not read here, so this note describes the doctrine rather than reporting a holding. |
| Notice the tenant must give | Via general lawRSA 540:13-d, I(a). Written notice with no waiting period before it, addressed with unusual practicality to the person to whom the tenant customarily pays rent, so the tenant does not have to identify the owner of record first. The conditions attach to the tenant rather than to the defect, and one of them is a burden rather than an act: the tenant must not be in arrears when the notice goes out, and must later prove both that fact and the notice itself by clear and convincing evidence, which is a heavier standard than the ordinary civil one. Keep the proof of service. The parallel route runs through the enforcement authority instead: under RSA 153:10-a VII the fire marshal or the delegated municipal authority serves its own written notice of violation, by certified mail or in person, describing the substandard condition and specifying the time limit for eliminating it. |
| Landlord cure period | Via general law, 14 daysRSA 540:13-d, I(b). Fourteen days from receipt of the written notice, "or, in an emergency, as promptly as conditions require", with no figure attached to the emergency; that clause is where a live carbon monoxide hazard belongs. Then read 540:13-d II, because a second period follows the first: the court may continue the possession action for a reasonable time not exceeding one month to let the landlord remedy the violation, and the tenant's withheld and accruing rent goes into court for the length of it. A landlord can therefore have something close to six weeks between the tenant's notice and a judgment, with the tenant's money held by the court for most of the second stretch. Where the clock was set by an enforcement authority rather than by the tenant, RSA 153:10-a VII lets that authority choose the time limit itself. |
Applies to every row above:New Hampshire has one of the plainest carbon monoxide statutes in the country and one of the narrowest routes from it to a tenant. RSA 153:10-a I requires the device in every multi-unit dwelling and rental unit that has an attached garage or a combustion-fuel appliance, and II-a makes the owner responsible for maintaining it in suitable condition. The words tenant and landlord then appear zero times in the whole section: enforcement belongs to the state fire marshal or a municipal authority the marshal appoints, and under VII that authority prepares a written notice of violation describing the substandard condition and setting its own time limit. The tenant is not a party to any of it. Meanwhile the remedy chapter routes through a different body of law entirely. RSA 540:13-d makes its defence available for a substantial violation of the standards of fitness in RSA 48-A or in local codes established under it, and RSA 48-A:14, the fallback list for municipalities that have adopted no housing code, is eleven closed items with no alarm among them: carbon monoxide, smoke and detector each appear zero times across the whole of RSA 48-A, against six occurrences of fire. The nearest items reach the source rather than the warning, exposed wiring creating a danger of fire at III and gas-line leaks or defective pilot lights at X. So the strength of a New Hampshire tenant's position on a dead alarm turns on whether their municipality has adopted a housing code that covers it. Chapters 540 and 48-A were read in full from Wayback captures of the Legislature's own merged chapter pages, December 2024 and January 2025 respectively, and RSA 153:10-a from an August 2023 capture; both gencourt.state.nh.us and gc.nh.gov refuse automated requests.
Penalties and Liability
New Hampshire's penalty structure under RSA 153:24, read with RSA 651:2, creates one of the most significant individual-versus-entity splits in any state CO alarm law. An individual who violates the CO alarm requirements faces a fine of up to $1,000 per offense. A non-natural person, meaning an LLC, corporation, partnership, or other business entity, faces up to $20,000 per offense. The two sit at different levels of the criminal code, and that is what produces the gap: RSA 153:24 makes a natural person guilty of a violation, which is non-criminal in New Hampshire, and any other person guilty of a misdemeanor.
That twenty-to-one ratio matters for rental operators. A landlord who holds rental properties through an LLC faces dramatically higher per-violation exposure than one who owns property individually. For multi-unit portfolio owners, a single inspection revealing noncompliant alarms across several units could produce cumulative penalty exposure in the tens of thousands of dollars.
Local Override Warning
New Hampshire's statewide CO alarm law under RSA 153:10-a is the legal floor, not the ceiling, and paragraph VI says so expressly. Two of the five municipalities read in August 2026 have built on it. Keene is the one to plan around: Section 42-94(a) requires every detector in a rental unit to take its operating power from the building electrical system, requires a lock on the circuit breaker where a dedicated circuit is used, requires interconnection where two or more detectors are needed in a unit, and requires the alarms to sound only inside that unit rather than actuating the building panel. Section 42-95 puts detectors on every floor level outside bedrooms including basements and on every level of a common stairway, with carbon monoxide detectors needed inside a bedroom only where that bedroom holds a carbon monoxide producing appliance. Section 42-92 then requires a fire department permit, with a plan or prior approval, to install a detector at all, in new and existing buildings alike. Concord amends its property maintenance code at Section 27-1-5 to forbid any person, tenant or occupant removing a battery, disconnecting power or otherwise disabling an alarm. Manchester, Meredith and Claremont add nothing. Verify with the applicable fire department before assuming state compliance is enough.
Frequently Asked Questions
Are CO detectors required in New Hampshire rental properties?
Who is responsible for CO detectors in New Hampshire rentals: landlord or tenant?
Where must CO alarms be placed in a New Hampshire rental unit?
What are the penalties for missing a CO detector in a New Hampshire rental?
Can a tenant remove or disable a CO detector in a New Hampshire rental?
Are New Hampshire hotels and motels covered by CO detector requirements?
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.
Sources and References
- RSA 153:10-a, Carbon Monoxide Detection Devices , statewide CO alarm requirements, triggers, placement, landlord/tenant duties, enforcement authority
- RSA 153:1, Definitions , definitions of dwelling, multi-unit dwelling, hotel, motel, and related terms
- RSA 153:24, Penalties , RSA 153:24 classifies the offence: a natural person is guilty of a violation, any other person of a misdemeanor. RSA 651:2 supplies the maxima, $1,000 at violation level and $20,000 for a non-natural person at misdemeanor level