Smoke Alarms, CO Detectors, and Storm Prep: What Illinois Law Actually Requires

Illinois doesn't leave home alarms to personal preference: state law says what kind of smoke alarm you can install, where carbon monoxide detectors must sit, and what landlords owe tenants on both. Most households are out of compliance on at least one point without knowing it. Here's the actual rulebook, plus the storm-season half of home safety that no law mandates but every Illinois spring tests.

The smoke alarm rule most people miss

Since January 1, 2023, when you replace a battery-powered smoke alarm in Illinois, the new one must have a sealed, non-removable 10-year battery (Public Act 100-0200, enforced by the State Fire Marshal). The old style that takes a 9-volt you swap twice a year is no longer legal to install in most homes. Hardwired alarms and homes built to be hardwired are handled differently, but if you're buying an alarm off a shelf for a bedroom hallway, buy the sealed 10-year kind.

The 10-year replacement clock applies regardless of battery type. Every alarm has a manufacture date printed on the back; if yours predates 2016, it's due now. Testing monthly is the official advice, and the honest version is: pick two fixed days a year you already remember (the time changes in March and November work) and actually do it then.

Carbon monoxide: the 15-foot rule

Illinois' Carbon Monoxide Alarm Detector Act has required, since 2007, a CO alarm within 15 feet of every room used for sleeping, in any home that burns fuel for heat, hot water, or cooking, or has an attached garage. That covers the large majority of Illinois housing, given how common gas furnaces are.

The 15-foot rule is where compliance quietly fails: one detector in the kitchen doesn't cover bedrooms at the other end of the house, and a hallway unit doesn't cover a bedroom behind a closed door on another floor. Walk your home once with the rule in mind. Combination smoke/CO units are a legal and cheap way to fix both requirements in one mount.

CO risk in Illinois is seasonal and concrete: it spikes when furnaces fire up in fall and during winter power outages when people run generators or heat with ovens. Never run a generator in a garage, attached or not.

Local note: if you rent, your landlord must install the required alarms, and you're typically responsible for keeping batteries in older removable-battery units. If a unit is missing or dead-on-arrival, that request to the landlord is one Illinois law is clearly on your side about. Put it in writing.

The severe-weather half: what a warning actually requires of you

No statute makes you prepare for tornado season, but Illinois averages dozens of tornadoes a year, and the sirens-to-shelter window is minutes. The preparation that matters is small and specific:

1. Alerts on every adult's phone, not one. Wireless Emergency Alerts are on by default; check they haven't been silenced. A $30 NOAA weather radio covers overnight warnings, which are the ones that kill, since sirens are designed for people outdoors.

2. Pick the shelter spot now. Lowest floor, interior room, no windows: a basement corner, an under-stair closet, an interior bathroom. If you're in an apartment above ground level, know which neighbor or hallway is the plan.

3. One box, one place. Flashlights, batteries, phone chargers, medication list, insurance cards, and copies of documents in a single grab-able spot. Assembling this takes twenty minutes in August and is impossible at 2 a.m. during an outage.

4. Know your flood pattern. For most Illinois households the realistic storm damage isn't a tornado, it's a flooded basement. If your block has a history, test the sump pump before the spring peak and know where water enters.

If you rent or share a home

• Ask who handles storm cleanup, sump-pump failures, and after-hours emergencies, before the first storm rather than during it.

• Confirm shared basements or interior hallways (your likely tornado shelter) stay unlocked and passable.

• Renters insurance is the cheap fix for the gap most tenants discover too late: the landlord's policy covers the building, not your belongings.

Before you go

• Buying a smoke alarm in Illinois? It must be the 10-year sealed-battery type.

• Check the manufacture date on every alarm; over 10 years old means replace, not re-battery.

• Walk the 15-foot rule for CO detectors around every sleeping room.

• Set alerts up on every phone in the house and agree on the shelter spot out loud once.

• Rules verified August 2026 against the Illinois State Fire Marshal's smoke alarm law page and the Carbon Monoxide Alarm Detector Act.

Quick answers

Are the twist-off battery smoke alarms illegal in Illinois now? Installing new ones is, in most homes: replacements must have sealed 10-year batteries under the 2023 law. Existing hardwired systems follow their own rules.

How many CO detectors do I need? Enough that every room used for sleeping has one within 15 feet, if your home has any fuel-burning appliance or an attached garage. For most single-family homes that's one per bedroom hallway per floor.

What's the single highest-value storm prep? Overnight-capable alerts (phone settings checked, or a weather radio) plus a pre-chosen shelter spot. Everything else is recovery comfort; those two are survival.