Combination smoke and CO alarm
Covers both fire and carbon monoxide detection in one unit — useful near attached garages and fuel-burning appliances.
Compare on AmazonSmoke Alarm & Carbon Monoxide Safety
Replace smoke alarms every 10 years from the manufacture date, not the install date. Put one inside every bedroom, one outside each sleeping area, and one on every level including the basement. Add CO alarms near fuel-burning appliances, attached garages, and sleeping areas.
Check your own home
The fastest way to see where you stand is our interactive checker — it tracks each alarm's age and compares your layout against the recommended count.
Go deeper
Expiration checker
How the 10-year rule works and how to read your alarm's date code.
CO alarm placement
Exactly where carbon monoxide alarms need to go — and where height stops mattering.
Checklist for landlords
What to document at every tenant turnover.
Checklist for new homeowners
A first-week walkthrough for a home you didn't wire yourself.
The basics
- Smoke alarms: inside every bedroom, outside each separate sleeping area, and on every level of the home, including the basement.
- Replace every smoke alarm 10 years from its manufacture date — check the date printed on the back of the unit, not when you happened to install it.
- Test every alarm monthly using the test button.
- Interconnected alarms (wired or wireless) mean every alarm sounds when one detects smoke — useful in larger homes.
- Add carbon monoxide alarms if you have fuel-burning appliances, an attached garage, or a fireplace/wood stove.
Tools and supplies to consider
These links go to an Amazon search so you can compare current options and prices.
10-year sealed battery smoke alarm
A sealed 10-year battery alarm removes the annual battery-swap chore for the life of the unit.
Compare on AmazonInterconnected wireless smoke alarm kit
When one alarm sounds, they all sound — useful in larger homes or homes with long hallways.
Compare on AmazonStandalone carbon monoxide alarm
A dedicated CO alarm for rooms near fuel-burning appliances or an attached garage.
Compare on Amazon9V alkaline batteries (multipack)
Keeps battery-powered alarms working between the annual replacement reminder.
Compare on AmazonLightweight step ladder
A stable way to reach ceiling-mounted alarms for testing and battery changes.
Compare on AmazonFrequently asked questions
Do I need to replace a hardwired alarm too?
Yes. The 10-year rule is based on how long the smoke sensor stays reliable, which applies whether the alarm is hardwired or battery-powered.
Is a combination smoke/CO alarm enough?
A combo unit covers both hazards in one device and is a reasonable choice for most rooms, as long as the placement still meets both smoke and CO guidance.
What does "interconnected" mean?
When one alarm senses smoke, every interconnected alarm in the home sounds — helpful for waking people in bedrooms far from the fire.
Related on HomeRuleCheck: when smoke alarms expire (the 10-year rule), where to place carbon monoxide alarms, how to dispose of an old smoke detector, and the smoke alarm coverage & expiration checker.