CO Detectors in Illinois: Owner and Tenant Duties Under 430 ILCS 135

Last verified: August 26, 2026

The Carbon Monoxide Alarm Detector Act, 430 ILCS 135, governs carbon monoxide detector law in Illinois under a single title. The act applies broadly to covered dwellings, including many rental units, and sets explicit placement, owner, and tenant obligations. It also establishes meaningful criminal exposure for willful noncompliance or tampering, which makes operational discipline important during leasing and maintenance cycles.

One answer on this page is open rather than settled, and Illinois is the only state in the fifty-one where it is: whether the duty reaches a hotel that was already standing. Thirty-five records answer yes, eleven answer conditional, four answer no, and this one says the answer could not be established. The reason is specific. Illinois adopts the 2015 edition of NFPA 101, which is paywalled and unreadable; the 2006 edition was read in full and carries no carbon monoxide requirement in any occupancy chapter, while the 2021 and 2024 editions carry one, so 2015 sits inside the window in which the duty arrived rather than either side of it. That is a failed bracket, and publishing it is more use than guessing. In practice, owners and operators should pair statutory requirements with Illinois State Fire Marshal guidance, maintain move-in operability records, document tenant notices and repairs, and audit placement distance during turnovers. Regular internal audits, supervisor spot checks, and quarterly maintenance reviews help confirm unit-level compliance before inspections or legal disputes consistently.

This combination supports legal defensibility, cleaner inspections, and safer residential operations across Illinois portfolios.

Key Takeaways

CO detector requirements for Illinois
Applies to homes?	Yes
Applies to rentals?	Yes
Applies to hotels/STRs?	Yes
Applies to schools?	Yes, under a condition
Applies to workplaces?	Not established here

Schools and workplaces

Schools: it depends, and the test is one you can apply to the building itself. Illinois legislates schools directly and then exempts the ones with nothing to detect. 105 ILCS 5/10-20.57 requires a school board to have each school under its authority equipped with approved carbon monoxide alarms or detectors, located within 20 feet of a carbon monoxide emitting device, kept in operating condition and inspected annually, with plans and protocols for what happens when one sounds. Section 5/34-18.49 does the same job for the Chicago district. The condition is the statute's own exemption: a school is exempt where it does not have, and is not close to, any source of carbon monoxide. Power depends on when the school was designed. Before 1 January 2016 a battery alarm is permitted, as is one permanently powered by the building's electrical system and monitored by any required fire alarm system; from that date the alarm must be permanently powered or be an approved detection system, monitored by any required fire alarm system. The State Fire Marshal's rules at 41 Ill. Adm. Code 112.230 and 112.250 supply the device specification for public schools under the same School Code delegation, and in Chicago the building code adds Section 915.2.3, which puts detectors in Group E and I-4 classrooms and sends the signal to a location staffed by school personnel unless the occupant load is 30 or fewer.

Workplaces: not established here. Three instruments are shut and a fourth was never opened, so this is recorded as open rather than as a negative. 430 ILCS 135, the Carbon Monoxide Alarm Detector Act, reaches dwelling units, and the State Fire Marshal's rules under it at 41 Ill. Adm. Code Part 112 have two audiences and no third: 112.200 sets the listing standard for alarms used where there are dwelling units as defined in the Act, and 112.230 and 112.250 cover public schools. Neither reaches an office, shop or factory. Chicago's building code Section 915, the only Illinois instrument found using the model occupancy list, carries Group E and I-4 classrooms alongside dwelling and sleeping units and no Group B, F, M or S. The fourth is NFPA 101, which 41 Ill. Adm. Code 100.7(b) adopts in its entirety, and the question it raises is not about an office. It is about an assembly occupancy, a restaurant, a bar, a theatre or a place of worship, which is non-residential, is not lodging, and is a place people work. In the 2021 and 2024 editions Section 12.3.4.4 requires carbon monoxide detection in a new assembly occupancy holding a permanently installed fuel-burning appliance or fireplace, served by a fuel-burning HVAC system, or adjacent to an attached garage, and the 2024 edition adds Section 13.3.4.4 for an existing one. No International Fire Code edition reaches Group A at all, so this is a route that exists only in the NFPA states and it was not examined when this row was set to false. Illinois modifies chapters 12 and 13 in the list at 100.7(c) and names carbon monoxide nowhere in it, so whatever the adopted edition says on this governs unchanged. Whether the 2015 edition Illinois adopts carries Section 12.3.4.4 cannot be read, and the window is wide. The 2006 edition was read in full from the Public.Resource.Org plain-text copy, 2,612,152 bytes: carbon monoxide occurs ten times and every one is in an annex discussing toxicity research or test-chamber conditions, with no requirement in any occupancy chapter, against a working control of 228 occurrences of "life safety code". So the assembly requirement entered somewhere after 2006 and was in place by 2021, and 2015 is inside that window rather than either side of it. It is the same failed bracket that leaves the existing-lodging question open in Illinois, and it fails for the same reason. What would close it: the text of NFPA 101 (2015) Chapter 12, or an Illinois source reproducing it. Eight older draft-report cycle labels were probed on 2026-08-22 and four more on 2026-08-23, including the first-draft-report pattern, and every one returned 404 against a control of HTTP 200 for the A2023 label. The Public.Resource.Org collection holds 101 in 2000, 2003, 2006 and 2012, and the 2012 item now answers is_dark true on the metadata endpoint while 2006 answers with thirty files, so 2006 is the copy a later reader should use. Treat this as an open question rather than as an exemption.

When Are CO Alarms Required?

Statewide law effective January 1, 2007 (Public Act 94-741).
Exemption may apply for units that (i) do not rely on combustion of fossil fuel for heat/ventilation/hot water, (ii) are not connected to a garage, and (iii) are not sufficiently close to another ventilated CO source, as determined by the local building commissioner.

Where to Install CO Alarms

Within 15 feet of every room used for sleeping purposes (dwelling units and structures with more than one dwelling unit).

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

Device Requirements

Must be an 'approved carbon monoxide alarm' that complies with Illinois State Fire Marshal rules, bears a nationally recognized testing laboratory label, and complies with the most recent UL or CSA standards.
May be battery powered, plug-in with battery back-up, or hardwired to AC power with secondary battery back-up.
Combination smoke/CO units are allowed if they comply with applicable requirements and clearly differentiate the hazard.

Landlord and Tenant Responsibilities

Landlord: Owner must supply and install all required CO alarms. Owner must provide one tenant per dwelling unit with written information regarding alarm testing and maintenance, and must ensure batteries are operational at move-in. Provision: Sec. 5, 10, 15, 20.

Tenant: Tenant must test and provide general maintenance, notify the owner/agent in writing of deficiencies the tenant cannot correct, replace required batteries (except owner ensures operable at move-in), and provide access for repairs. Provision: Sec. 5, 10, 15, 20.

Responsibility allocation (owner vs tenant) is explicitly stated in 430 ILCS 135/10(c).

Full Illinois landlord and tenant carbon monoxide duties, with citations

Enforcement

Enforced by: Local municipal Authority Having Jurisdiction (AHJ) / local building commissioner (as referenced in the statute and OSFM guidance).

Enforcement typically occurs:

During local inspections where applicable; enforcement may also occur following complaints or incidents.

OSFM guidance notes AHJs may enforce additional local requirements beyond the state act.

What a Tenant Can Do in Illinois

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

"Via general law" means the Illinois 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 Illinois, with the citation or the body of law searched for each.
Rent withholding	Via general lawJack Spring, Inc. v. Little, 50 Ill. 2d 351 (1972). No Illinois statute grants rent withholding. The Supreme Court held in Jack Spring that every residential lease carries an implied warranty of habitability and that the duty to pay rent depends on the landlord's performance of it, which is what lets a tenant raise the condition as a defence. That is a defence in an eviction case, not a safe self-help step: a tenant who simply stops paying invites the eviction in which the defence then has to be won.
Repair and deduct	Via general law765 ILCS 742/5. Capped at the lesser of $500 or one-half of one month's rent, and the work must be done in a workmanlike manner and to code. The cap is the binding limit for CO work: a single alarm falls under it comfortably, a vented-appliance repair usually will not. Unavailable where the condition was caused by the tenant, the tenant's family, or someone on the premises with the tenant's consent.
Right to end the lease	No provision foundSearched: 765 ILCS 705 (Landlord and Tenant Act), 765 ILCS 742 (Residential Tenants' Right to Repair Act) and 430 ILCS 135 (Carbon Monoxide Alarm Detector Act). No provision lets a tenant end the lease over an uncorrected habitability defect. The one condition-based termination in 765 ILCS 705 is written for flooding and runs on its own 30-day notice window, and it does not reach an alarm defect. Constructive eviction under the Jack Spring warranty is the remaining route, and it is decided case by case rather than granted by a section.
Notice the tenant must give	Via general law765 ILCS 742/5. There is no waiting period, but there is a form requirement most states do not have: the notice must go by registered or certified mail or another restricted delivery service, to the address on the lease or the landlord's last known address. Only Maine and Wyoming prescribe how the notice travels as well; the rest of the fifty-one prescribe no method at all, which makes the delivery receipt the thing an Illinois tenant must not lose. A text message or an email does not start the 14-day clock in the next column.
Landlord cure period	Via general law, 14 days765 ILCS 742/5. Fourteen days after the tenant's notice, or "more promptly as conditions require in the case of an emergency". A CO alarm that does not work in a unit with a fuel-burning appliance is the kind of condition that clause exists for, so the fourteen days is a ceiling rather than an entitlement.

Applies to every row above:Illinois has no statewide landlord-tenant act of the kind most of the fifty-one rely on. The Carbon Monoxide Alarm Detector Act puts installation on the owner and batteries on the tenant and backs it with criminal penalties only, so it creates no tenant remedy. Four of the five columns below therefore rest on one short statute, the Residential Tenants' Right to Repair Act, and the fifth on a 1972 Supreme Court decision. The remedies Illinois tenants actually use in the largest city, under the Chicago residential landlord and tenant ordinance, are municipal and are not recorded in the table above.

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

What Illinois Requires in Lodging

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

Hotels already standing: not established. Whether the Illinois requirement reaches a hotel that was already standing when the rule took effect has not been established here. Most hotels are existing buildings, so treat this as an open question rather than as an exemption, and confirm it with the local building or fire authority before deciding you carry no retrofit duty.

Operator duty: An Illinois hotel or motel operator takes the duty from the Life Safety Code rather than from the Carbon Monoxide Alarm Detector Act. 430 ILCS 135/5 defines a dwelling unit as a room or suite of rooms used for human habitation and gives its examples as a single family residence, each living unit of a multiple family residence and each living unit in a mixed use building; 430 ILCS 135/10 then puts the installation duty on the owner of a structure containing more than one dwelling unit. Neither section names a hotel, a motel or transient occupancy anywhere. What reaches lodging is 41 Ill. Adm. Code 100.7, which adopts NFPA 101, Life Safety Code (2015) in its entirety under the Office of the State Fire Marshal, with no modification touching Chapter 28 or Chapter 29 and no mention of carbon monoxide in the modification list. For a new hotel or dormitory the duty is the one at 28.3.4.6 in the 2012 edition and 28.3.4.7 in the 2021 and 2024 editions, which impose the same requirement on the same two triggers: a guest room or guest suite with a communicating attached garage, or one containing a permanently installed fuel-burning appliance. For an existing hotel the answer is still open, and the applies_to note explains why the same reading cannot settle it.

Full Illinois hotel and short-term rental requirements

Penalties for Non-Compliance

Willful failure to install or maintain required CO alarms is a Class B misdemeanor. Tampering with/removing/destroying/disconnecting alarms or removing batteries (outside inspection/maintenance/replacement) is a Class A misdemeanor for a first conviction and a Class 4 felony for a second or subsequent conviction.

430 ILCS 135/15 (Violation).

Additional Notes

A hotel guest room sits in a genuine gap in the Carbon Monoxide Alarm Detector Act rather than plainly inside or outside it, and a whole-house short-term rental does not, which is why the two rows above differ. Section 5 defines a dwelling unit as "a room or suite of rooms used for human habitation", and then adds that it includes a single family residence, each living unit of a multiple family residence and each living unit in a mixed use building. The opening words are wide enough to take in a guest room, while every example that follows is a form of residential tenancy, and the word hotel appears nowhere in the definitions at section 5, the duty at section 10 or the exemptions at section 20. Section 20 then frames its carve-outs around "residential units", which pulls the same way. Nothing in the act resolves which reading governs a hotel room, so a lodging operator in Illinois should confirm classification with the local authority having jurisdiction and check for a municipal ordinance, and no statewide operator duty is recorded above because none has been established. The ambiguity is specific to the guest room. A house or a condominium let by the night is named in the definition rather than argued into it, which is the separate note below.
The Fire Marshal's own rules under the act confirm the gap rather than closing it. Part 112 of Title 41 of the Illinois Administrative Code is the rule the act's definition of an approved alarm points to, and it turns out to be a device specification with two audiences. Section 112.100 says the part implements the School Code delegation on carbon monoxide detectors in public schools and carries the alarm specifications the act established. Its two operative sections match that: 112.200 sets the listing standard for alarms used in an occupancy or structure with one or more dwelling units "as defined in the Act", and 112.230 and 112.250 do public schools. Lodging appears in neither, and 112.200 hands the coverage question straight back to the act's own definition, which is where the ambiguity started.
A different instrument may answer, and it is the one worth reading next. Section 100.7 of the same title adopts NFPA 101, the Life Safety Code, 2015 edition, in its entirety, subject to the Fire Marshal's modifications in subsection (c), and section 100.3(b) applies that part to localities within Illinois while section 100.3(d) puts the duty of compliance on the owner, occupant or lessee. That code carries carbon monoxide provisions inside its occupancy chapters, at 28.3.4.6 for new hotels and dormitories and 29.3.4.6 for existing ones, and the Fire Marshal's modifications never mention hotels, dormitories or either chapter. What is not established is the content of those two sections in the 2015 edition. A section title is not a requirement, and this project does not record one as if it were, so lodging applicability stays open. Two things narrowed on 2026-08-20 without closing it, and both are recorded so the next reader starts from here. The chapters themselves are no longer unreadable in general: NFPA publishes its Second Draft Reports free and account-free, they reproduce the base edition rather than only the changes to it, and the 2021 and 2024 texts of both chapters were obtained that way and are byte-identical to each other. What that route does not reach is 2015. Ten cycle labels were probed and only the two most recent answered; seven more were tried on 2026-08-20, including the labels that would carry the 2015 and 2018 texts, and every one returned 404. The second thing is a warning about the numbers above rather than about the content. In the 2021 and 2024 editions the new-hotel carbon monoxide section is 28.3.4.7, and 28.3.4.6 is "Smoke Alarms"; in the 2012 edition carbon monoxide sat at 28.3.4.6. Whether the move happened at 2015, 2018 or 2021 is not established, so the citation above is left exactly as it is. It is correct if the move came later than 2015 and points at the smoke alarm section if it came earlier, and modernising it to 28.3.4.7 on the strength of a different edition would be the error this note exists to prevent. The existing-hotel section did not move: 29.3.4.6 is carbon monoxide in every edition read. Anyone with an NFPA account or a library copy of the 2015 edition can close all of this by reading two sections.
Whether the Illinois rule reaches a hotel that was already standing is not established, and the bracket that answered the new-hotel question fails here for a reason worth seeing. The instrument is the same one: 41 Ill. Adm. Code 100.7 adopts NFPA 101, the Life Safety Code, 2015 edition in its entirety, and none of the Fire Marshal's modifications in subsection (c) touches Chapter 28 or Chapter 29. Chapter 29 is the one for existing hotels and dormitories. The 2015 edition is not publicly readable, so the usual method is to read the editions either side and see whether they agree. They do not. In the 2006 edition, read in full for this page, Chapter 29 carries "29.3.4.4 Detection. (Reserved)" and asks for no carbon monoxide device anywhere in the chapter. In the 2021 and 2024 editions, also read in full, Section 29.3.4.6.1 requires carbon monoxide alarms or detectors in existing hotels and dormitories where a guest room or guest suite has a communicating attached garage or contains a permanently installed fuel-burning appliance or fuel-burning fireplace, and the two editions are word for word identical. So the requirement was written into Chapter 29 somewhere between those editions, and 2015 sits inside that window. What refused: NFPA's own second draft reports carry the 2021 and 2024 base texts and no earlier cycle, the Public Resource copy of the 2012 edition has been darkened since this project last recorded it as available, and the publisher's own portals need an account. What the answer would change for you: most hotels are existing buildings, so this decides whether an Illinois operator who has pulled no permit owes a retrofit or owes nothing, and the honest position is that the edition Illinois adopted is the one nobody here can open.
A short-term rental asks a different question from a hotel here, and the Act answers it even though it leaves the hotel open. Section 5 of the Carbon Monoxide Alarm Detector Act defines a dwelling unit as "a room or suite of rooms used for human habitation, and includes a single family residence as well as each living unit of a multiple family residence and each living unit in a mixed use building", and Section 10 requires every dwelling unit to be equipped with at least one approved carbon monoxide alarm in operating condition within 15 feet of every room used for sleeping purposes. A house let by the night is a single family residence and a condominium let by the night is a living unit of a multiple family residence, so both are named in the definition rather than argued into it. The two exemptions at Section 20 are physical rather than temporal: a residential unit in a building that does not rely on combustion of fossil fuel for heat, ventilation or hot water, is not connected in any way to a garage and is not sufficiently close to a ventilated source of carbon monoxide, and a residential unit not sufficiently close to any source, each as the local building commissioner determines. Neither mentions transient occupancy, letting, or length of stay. What stays open is the hotel guest room, where the definition's opening words and the examples that follow pull in different directions, and that question is recorded separately on this page.

Local Rules That Differ From State Law

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

Aurora

Aurora requires monitoring, which no Illinois statute does. Its amendments to the Existing Building Code add Section 1001.2.2.2, making the conversion of a one- or two-family structure to a lodging house a change of use, and a change of use there demands both a full electrical upgrade to current new-construction standards and a smoke and carbon monoxide detection and alarm system that is code compliant and fully monitored through a central station. A landlord converting a house to rooms in Aurora buys a monitored system; the same conversion anywhere else in Illinois needs battery alarms. Aurora also widened who is covered. Its property maintenance amendments add Section 706, which requires every dwelling or rooming unit to satisfy both the local code and the state minimum, so the rooming unit carries the duty in Aurora. The state Act mentions a rooming unit once, inside the occupant's maintenance duty at Section 10(c), and never defines it or makes it the subject of the installation duty in 10(a) or 10(b).

Aurora Code of Ordinances Sections 12-17.7 (Existing Building Code Section 1001.2.2.2, Ordinances 018-013 and O18-049) and 12-102 (Property Maintenance Section 706) Checked 2026-08-03.

Naperville

Naperville hangs its requirement on a transaction the state act never mentions. Section 5-11-6 lists the minimum requirements for converting a building to condominiums, and item 3 of that list requires carbon monoxide detectors to be installed and maintained in all residential and commercial condominiums. Two things follow. A Naperville developer turning an apartment building into condominiums has to satisfy the detector requirement to complete the conversion, which turns a housing-safety rule into a condition of the sale; and the words "and commercial" carry the duty into buildings that 430 ILCS 135 never reaches, since that act speaks of dwelling units. Separately, Naperville's Residential Code amendments at Section 5-1B-2 are the clearest illustration in this dataset of why an edition has to travel with a section number. Naperville adopts the 2024 edition of the International Residential Code at Section 5-1B-1, and the 2024 edition reordered Chapter 3, so its carbon monoxide provisions are numbered in the R311 range rather than the R315 range that every earlier edition used. The city's amendments follow that numbering exactly. R311.4, single and multiple station carbon monoxide detectors, requires installation to the manufacturer's instructions. R311.6, the power source rule, has its second exception rewritten so that alarms in the part of a residence untouched by a renovation or addition may be battery powered, while alarms inside the area of work must meet the full power source requirement. That is a sensible split and it is invisible to anyone searching for R315, which is where the same subject sat until 2024 and where most published guidance still looks. In the 2024 edition R315 is the sleeping loft section, so a reader who goes there finds a real provision about something else entirely.

Naperville Municipal Code Sections 5-11-6(3) (minimum condominium conversion requirements) and 5-1B-2 (Residential Code amendments) Checked 2026-08-03.

Chicago

Chicago keeps its carbon monoxide rule in the building code rather than the housing code, and the version there asks more of a landlord than 430 ILCS 135 does, starting at the socket. Section 14B-9-915.4.1 requires an alarm to draw primary power from the building wiring wherever a commercial source serves the building, leaving the battery as backup only; battery-powered units are confined to buildings with no commercial power at all. The state act accepts a plain battery alarm anywhere in Illinois, so the cheapest lawful device outside the city fails inside it. Chicago measures placement by another standard as well. The state act fixes an alarm within 15 feet of every sleeping room, while Section 915.2.1 asks for detection outside each separate sleeping area in the immediate vicinity of the bedrooms, then adds a trigger the state act never states: a fuel-burning appliance sitting in a bedroom or its attached bathroom pulls the detector into that bedroom. The city also reaches past dwellings. Section 915.2.3 puts detectors in classrooms in Group E and I-4 occupancies and sends the alarm signal to an on-site location staffed by school personnel unless the occupant load is 30 or fewer, where 430 ILCS 135 reaches dwelling units alone. In a new building that needs a fire alarm system, Section 915.3.1 wires the detectors into it under NFPA 72. All of this governs new buildings, and Section 915.1 sends existing ones to Title 14X.

Chicago Municipal Code Section 14B-9-915 (Building Code, adopting IBC Section 915 with modifications; added Coun. J. 4-10-19, p. 100029, amended Coun. J. 2-19-20, p. 14474). Coun. J. 4-10-19, p. 100029, Art. XXII, Section 6 repealed Chapter 13-64, the chapter once cited for a 40-foot rule. Checked 2026-08-04.

What was checked:Checked Aurora, Naperville and Chicago, and all three diverge. Aurora and Naperville each attach the alarm to an event rather than to an appliance, the reverse of how 430 ILCS 135 works, and both were read through the code publisher's own search index, control-tested at 235 and 366 provisions for the word building and 3 and 4 for smoke detector. Chicago corrects a claim that secondary sources repeat. They cite Municipal Code 13-64-190 for a rule measuring 40 feet from every sleeping room against the state act's 15, and the chapter that carried it is gone: the City Council repealed all of Chapter 13-64 on 10 April 2019, and the current edition of the code, 2026 S-73, prints that chapter as RESERVED above an editor's note recording the repeal. The same April 2019 ordinance enacted Title 14B, whose Section 14B-9-915 governs today and is recorded below. Part of Chicago stays open. Section 915.1 sends existing buildings to the Chicago Minimum Requirements for Existing Buildings at Title 14X, and that text refused both routes tried: the code publisher paywalls its Existing Building Code, and American Legal serves Title 14X section headings with empty bodies. A tenant in an older Chicago building has no verified answer here yet. Cook County and the collar-county municipalities outside these three were not searched.

Local sweep last reviewed 2026-08-04.

Official Sources & References

Office of the Illinois State Fire Marshal, 41 Ill. Adm. Code 100.7, adoption of NFPA 101 by reference , 100.7(b), the incorporation list, and the no-later-editions clause (fire code, accessed 2026-08-26)
An edition-currency check, run on 2026-08-26 against the rule itself. 100.7(b) incorporates "NFPA 101, Life Safety Code (2015) (adopted in its entirety, subject to the OSFM modifications in subsection (c))", and separately "NFPA 101, Life Safety Code (2000) (only to the extent cited in subsections (c)(1), (c)(2) and (c)(6))". The Part was amended at 43 Ill. Reg. 10008, effective 1 January 2020, and the 2015 edition is still the one in force. The clause that closes the question is the Part's own: "Standards incorporated by reference in this Part do not include any later editions or amendments, unless explicitly stated otherwise in this Part." So the 2015 edition governs and a newer one does not arrive by default. That sentence is worth recording because a search summary asserted the opposite on the same day, reporting that Illinois treats a newer edition of NFPA 101 as equivalent. The rule text does not say it. A summary of a search result is not a source, and this is the second time on this project that one has offered a clause the instrument does not contain. The practical consequence is unchanged and is why several rows here stay open: the 2015 edition is the one NFPA's Second Draft Reports do not reproduce, so the bracket that closed Georgia on the 2024 edition and Florida on the 2021 does not reach Illinois.
Illinois Compiled Statutes, Carbon Monoxide Alarm Detector Act (430 ILCS 135/) , Sec. 5 (definitions) and Sec. 10 (installation and responsibility), both read in full 2026-08-22; Sec. 15 and 20 (state code, accessed 2026-02-16)
Primary statute: definitions (Sec.5), installation/owner-tenant responsibilities (Sec.10), penalties (Sec.15), exemptions (Sec.20).
Office of the Illinois State Fire Marshal, What is CO (Carbon Monoxide)? (Fact Sheet) , Carbon Monoxide Alarm Detector Act overview (agency guidance, accessed 2026-02-16)
OSFM fact sheet noting the act’s effective date and that local AHJs enforce requirements.
Office of the Illinois State Fire Marshal, Carbon Monoxide Detectors (Guidance) , Install within 15 feet of sleeping rooms (agency guidance, accessed 2026-02-16)
OSFM guidance reinforcing the 15-foot sleeping-room proximity requirement and practical placement tips.
41 Ill. Adm. Code Part 112, Carbon Monoxide Alarms and Detectors , Sections 112.100 (Purpose and Scope), 112.200 (Dwelling Units) and 112.230 (Public Schools) (state code, accessed 2026-08-04)
The State Fire Marshal's rules made under the Carbon Monoxide Alarm Detector Act, effective 29 July 2016. A device specification rather than a coverage rule: 112.100 states the part implements the School Code delegation on public schools and carries the act's alarm specifications, 112.200 sets the UL 2034 listing standard for alarms used where there are dwelling units "as defined in the Act", and 112.230 and 112.250 cover public schools. No section reaches lodging, and 112.200 refers the coverage question back to the act's definition.
41 Ill. Adm. Code Part 100, Fire Prevention and Safety , 41 Ill. Adm. Code 100.3 (jurisdiction and responsibility of owners), 41 Ill. Adm. Code 100.7 (adoption of NFPA 101 by reference) and 41 Ill. Adm. Code 100.9 (more recent editions) (fire code, accessed 2026-08-22)
100.7(b) adopts NFPA 101, Life Safety Code (2015) in its entirety, subject to the modifications in 100.7(c). 100.3(b) applies the part to localities within Illinois, 100.3(d) puts compliance on the owner, occupant or lessee, and 100.3(c)(2) has local fire officers enforce it under the Fire Marshal's direction except in localities with standards equal to or higher. The modifications in 100.7(c) never mention hotels, dormitories or the Life Safety Code's chapters 28 and 29: those terms return zero across the section while "NFPA 101" returns thirty-four in the same text. 100.9 read for the first time on 2026-08-22: "Use of a newer edition of NFPA 101, Life Safety Code in its entirety will be considered equivalent to use of NFPA 101, Life Safety Code (2015) and may be considered by OSFM to be equal to or higher than this Part, as required by Section 100.3(g)(3)." The modification list in 100.7(c) was re-read the same day against the chapter numbers it names: chapters 12 and 13, chapters 16 and 17, chapter 24, and sections 8.6.6, 6.1.14, 16.1.1.8, 17.1.1.8 and 10.13. Chapters 28 and 29 appear on neither list and carbon monoxide is named nowhere in it, so the model text governs lodging in Illinois.
430 ILCS 135/10 - Installation and responsibility requirements , Sec. 10 (state code, accessed 2026-02-17)
Direct statutory section covering placement and owner-tenant responsibilities.
430 ILCS 135/5, 135/10 and 135/20, Carbon Monoxide Alarm Detector Act, definition of dwelling unit, the alarm duty, and the two exemptions (state code, accessed 2026-08-22)

Disclaimer: This page explains the law as it stood on August 26, 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 Illinois dwellings fall under 430 ILCS 135?

430 ILCS 135 applies to covered dwelling units and requires approved carbon monoxide alarms in locations tied to sleeping areas. The law is not limited to one housing type and is frequently used in both owner-occupied and rental compliance workflows. Illinois State Fire Marshal guidance reinforces the legal baseline and practical placement expectations. Owners should confirm classification for mixed-use properties, but the core rule is that covered residences must maintain operable devices. The safest approach is to treat the statutory language as a minimum standard and add local code checks before occupancy.

How close must Illinois CO alarms be to sleeping rooms?

Illinois placement language in 430 ILCS 135 and related Fire Marshal guidance generally requires alarms within 15 feet of rooms used for sleeping. Device selection must satisfy approved listing standards, and combination smoke and CO units are acceptable when they meet code requirements for both hazards. During inspections, code officials typically look at both distance and operability, not just whether a device exists somewhere in the unit. Property managers should include placement verification in turnover inspections so distance errors are corrected before new occupancy begins.

Who is responsible for maintenance in Illinois rentals?

Illinois divides duties between owner and tenant under 430 ILCS 135. Owners must provide required alarms and ensure operability at move-in, while tenants are expected to perform routine testing, replace batteries where required, and notify the owner of defects they cannot fix. This responsibility split should appear clearly in lease documents and move-in packets. When maintenance records are incomplete, disputes can escalate quickly after incidents. A written policy that tracks notice, repair date, and retesting can significantly reduce compliance risk for both parties.

What penalties apply for CO alarm violations in Illinois?

Illinois treats willful noncompliance seriously under 430 ILCS 135/15. Failure to install or maintain required alarms can be prosecuted as a Class B misdemeanor, while tampering offenses can escalate from a Class A misdemeanor to a Class 4 felony for repeat violations. These are stronger consequences than many states that rely only on civil citations. Because criminal exposure is possible, owners and managers should prioritize prompt repair and documentation after any defect report. Compliance files should cite both Section 10 obligations and Section 15 penalties.

In Illinois, when can an all-electric unit still require a CO alarm?

Exemptions can apply in limited scenarios, but Illinois operators should not assume every all-electric unit is outside scope. 430 ILCS 135 includes conditional carve-outs, and local interpretation by the authority having jurisdiction can affect how those exemptions are applied. Buildings connected to garages or adjacent combustion sources may still present risk factors that support alarm installation. Because local enforcement can vary, many compliance teams install alarms in all-electric units as a consistent safety standard unless a clear exemption is documented.

How do Illinois requirements compare with Michigan permit triggers?

Illinois relies on a statewide statutory framework in 430 ILCS 135 with explicit owner-tenant duties and criminal penalty language. Michigan often emphasizes permit-related triggers under MCL 125.1504f and related provisions, which can shift timing and enforcement context. If you manage assets in both states, your compliance checklist should separate statutory duty workflows from permit-trigger workflows. For the Michigan model and cross-reference citations, review Michigan CO detector laws before drafting shared operating procedures.

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