Smoke and Carbon Monoxide Alarm Compliance: A Landlord's Liability Checklist

Almost every landlord obligation has some gray area — except this one. Smoke and carbon monoxide alarm requirements are written into state statutes, local fire codes, and often your insurance policy, and when a fire or CO incident happens, the first thing investigators and attorneys ask for is your installation and testing records. If you can't produce them, you're defending a negligence claim with nothing but your memory. This guide covers what to install, where, how to document it, and how to handle the tenant who keeps pulling the batteries out.

Why alarms are the highest-liability, lowest-cost item you own

A hardwired smoke alarm costs about $25. A sealed 10-year CO/smoke combo runs $40–$60. Against that, consider what a missing or disabled alarm creates: potential criminal exposure in some states, automatic policy questions from your insurer, statutory damages in tenant-friendly jurisdictions, and — in the worst case — a wrongful death claim that will not be covered by the exclusions in a thin landlord policy.

Most landlords do install alarms. Where they lose is documentation. "I put one in every bedroom when I bought the place in 2019" is not evidence. A signed move-in form showing the tenant tested each device, plus dated photos, is.

In an alarm case, the question is almost never "did you install one?" It's "can you prove it was working on the day the tenant took possession, and that you responded when they told you it wasn't?" Those are records problems, not hardware problems.

What the rules generally require

Requirements vary by state and city, and retrofit rules often depend on when the building was constructed or last substantially remodeled. Verify your state statute and your local fire marshal's rules before you rely on any general summary. That said, the modern baseline in most of the US looks like this:

• Smoke alarms inside every sleeping room, in the hallway or area immediately outside each sleeping area, and on every level of the unit including basements.
• Carbon monoxide alarms on each level and near sleeping areas in any unit with a fuel-burning appliance (gas furnace, gas range, gas or oil water heater, fireplace, wood stove) or an attached garage.
• Interconnection in newer construction and gut rehabs — when one sounds, they all sound. Retrofits often permit wireless interconnected units.
• Sealed 10-year lithium batteries for battery-only alarms. Several states (California, Oregon, Maryland, New York and others) have moved to require them precisely because tenants remove removable batteries.
• Landlord installs and maintains; tenant tests and reports. Nearly every statute splits it this way: you supply working devices at the start of tenancy, the tenant notifies you of failure, and you repair promptly.

Where CO alarms trip people up

Landlords often assume an all-electric unit is exempt. Check two things first: is there an attached garage, and is there any shared mechanical room or common chimney? Both create CO pathways. Also remember a detached garage under the same roofline can still count. When in doubt, install one — the cost of a false exemption is enormous, and the cost of an extra alarm is a takeout dinner.

Placement details that fail inspection

• Not within 3 feet of an HVAC supply register or ceiling fan blade path (nuisance airflow).
• Not within 10 feet of a cooking appliance for photoelectric alarms — closer distances trigger constant kitchen nuisance alarms, which is the #1 reason tenants disable devices. Where layout forces it, use a photoelectric model with a hush feature.
• Not in a bathroom or within 3 feet of a bathroom door with a tub or shower.
• On sloped or cathedral ceilings, mount within 3 feet of the peak but not in the apex itself.
• CO alarms: follow manufacturer height guidance. Most modern units are approved for any height; older ones are not.

Build an alarm record that actually protects you

Treat every device like an asset with a paper trail. For each unit, keep a simple alarm log recording:

1. Device location (e.g., "Bedroom 2 ceiling, north wall").
2. Type — smoke (photoelectric/ionization/dual), CO, or combo.
3. Manufacture date, stamped on the back of every listed alarm. This matters: smoke alarms expire 10 years from manufacture, CO alarms typically 5–10 years depending on model. An expired device is treated as no device.
4. Install date and who installed it.
5. Every test: date, who tested, pass/fail.
6. Every service event: battery swap, replacement, tenant report, your response time.

The cleanest way to run this is as a recurring item on your maintenance calendar with photos attached to the unit record. If you're already tracking inspections and repairs digitally — you can see how that flows in the Rentmark demo dashboard — add alarms as a standing annual task so it never depends on memory.

The move-in test is the single most valuable record

At move-in, walk the unit with the tenant, press the test button on every alarm, and record it on your move-in inspection form with a line for each device and a tenant signature. Photograph each alarm in place with the room visible in frame. That one page does more for you legally than everything else combined, because it establishes working devices on day one and shifts the maintenance-notification duty to the tenant going forward.

Lease language you should be using

Your lease should include an alarm clause that does four things:

• Acknowledges that working smoke and CO alarms were present and tested at move-in, listing the count and locations.
• Prohibits disabling, removing, covering, painting, or taking batteries from any device — and states that doing so is a material lease violation.
• Requires written notice (text or in-app message counts if you say so) within 24 hours of any alarm that chirps, fails a test, or is damaged.
• Grants entry for testing and replacement with proper statutory notice, and immediate entry in an emergency.

Add a sentence that tenants are responsible for the cost of replacing devices they removed or destroyed. Just know that recovering that from the deposit is subject to your state's rules on allowable deductions and itemization deadlines — review the specifics in our security deposit laws by state guide before you write the charge onto a move-out statement. In some states, tight itemization windows mean a late letter forfeits the charge entirely; California's 21-day rule is a common example.

Handling the tenant who disables the alarm

This is common and it is dangerous. The usual causes are kitchen nuisance alarms, a low-battery chirp at 3 a.m., or a steam-prone bathroom nearby. Your response should be operational before it's punitive:

1. Fix the root cause. Move or swap the device — a photoelectric alarm near a kitchen dramatically reduces cooking false alarms compared with an ionization unit.
2. Switch to sealed 10-year units so there's no battery to remove and no midnight chirp for a decade.
3. Document the incident in writing. A dated notice describing the disabled device, the reinstallation date, and a reminder of the lease term creates the record you need if there's ever a claim.
4. Escalate only if repeated. A second removal after written warning justifies a formal cure-or-quit notice. Courts take alarm tampering seriously because it endangers neighbors too.

Never accept "the tenant disabled it" as a defense you can rely on passively. In many states, your duty to maintain persists — which is why testing at every routine inspection matters more than the lease clause.

An annual alarm routine that takes 15 minutes per unit

• Once per year (pair it with your HVAC filter visit or annual inspection): test every device, check manufacture dates, replace anything within a year of expiration, and photograph each unit.
• At every turnover: replace any alarm older than 7 years rather than reusing it, since the next tenancy likely outlives the device.
• Before any city rental inspection: confirm counts and placement against the current local code. Missing alarms are the most-cited violation in most municipal rental inspection programs.
• Whenever you add a gas appliance or convert a garage: re-evaluate CO coverage immediately.

Buy alarms in bulk with matching models so replacement is predictable, and write the install date on the device with a marker so a future tester can read it from a ladder without pulling it down.

Key takeaways

• Smoke alarms go in every bedroom, outside each sleeping area, and on every level; CO alarms go anywhere there's a fuel-burning appliance or attached garage.
• Alarms expire — 10 years for smoke, often 5–10 for CO. Check the manufacture date stamped on the back, not the install date.
• The move-in walkthrough with a signed, per-device test record is your strongest piece of evidence in any claim.
• Sealed 10-year battery units and correctly placed photoelectric alarms eliminate most of the reasons tenants disable devices.
• Keep a dated alarm log per unit covering installs, tests, tenant reports, and your response time.
• Charging a tenant for a removed alarm only works if your deposit itemization follows your state's deadline and format rules.

Frequently asked questions

Who is responsible for replacing smoke alarm batteries — landlord or tenant?

In most states the landlord must supply working alarms at the start of the tenancy, and the tenant is responsible for routine battery replacement and for notifying the landlord of failures during occupancy. Several states have shifted entirely to sealed 10-year batteries, which removes the question. Spell the split out in your lease either way.

Do I need a CO alarm in an all-electric unit?

Often not, but check for an attached garage, a shared boiler or mechanical room, a fireplace, or a gas dryer hookup — any of those usually triggers the requirement. Given the low cost, many landlords install combo alarms everywhere rather than track exemptions unit by unit.

What happens if a tenant removes the alarm and there's a fire?

Your lease clause and written warnings help, but they rarely eliminate exposure on their own. Courts look at whether you installed compliant devices, whether you tested them periodically, and whether you responded to known problems. Documented annual testing is what turns your position from "we told them not to" into "we maintained the property."

How often should I test alarms in an occupied rental?

At minimum annually, plus at every move-in and move-out. If your state or city requires more frequent testing, follow that. Always give proper written entry notice unless it's an emergency.

The bottom line

Alarm compliance isn't a hardware problem — it's a recordkeeping problem wearing a hardware costume. Landlords who get burned almost always installed something; they just couldn't prove when, where, or that it worked. Logging installs, tests, and tenant reports alongside your inspections, leases, and maintenance history — which is exactly what Rentmark is built to keep in one place — turns a scary liability into a 15-minute annual task you can document on demand.