Key takeaways
- Smoke alarms belong inside each bedroom, outside each sleeping area and on every level of the home, including the basement.
- Carbon monoxide alarms go outside sleeping areas and on each level, and you should leave the home and call 911 if one sounds.
- Test every alarm once a month, and replace smoke alarms 10 years after the manufacture date printed on the back.
- Interconnected alarms, which all sound when one does, give everyone in the home the earliest warning.
- A small fire extinguisher and a practiced escape plan with two ways out of every room complete your home's basic fire safety.
Smoke and carbon monoxide alarms are some of the cheapest safety upgrades you can make in a new home, and some of the most important. Many buyers inherit alarms of unknown age from the last owner, in the wrong places or with dead batteries. This guide explains where each type of alarm goes, how to test and replace them, how to spot carbon monoxide poisoning, and how to round out your plan with a fire extinguisher and an escape plan.
Why do working alarms matter so much?
Working smoke alarms give you the early warning you need to get out. The NFPA found that from 2018 to 2022, nearly three out of five home fire deaths happened in homes with no smoke alarms or with alarms that didn’t work. The death rate was about 60% lower in homes with working smoke alarms.
- No smoke alarm 43% (43%)
- Alarm present but failed 16% (16%)
- All other home fire deaths 41% (41%)
View data as table
| Item | % | |
|---|---|---|
| No smoke alarm | 43% | 43% |
| Alarm present but failed | 16% | 16% |
| All other home fire deaths | 41% | 41% |
Source: National Fire Protection Association (as of October 18, 2026)
Those figures come from the National Fire Protection Association’s June 2024 report (NFPA). In that period, 43% of home fire deaths occurred in homes with no smoke alarm and 16% in homes where an alarm was present but failed to operate. The NFPA found that missing, dead or disconnected batteries and disconnected hardwired alarms were the most common factors when alarms failed.
Time is short in a fire. The U.S. Fire Administration (USFA) warns that you could have less than 2 minutes to escape a home fire once the smoke alarm sounds (USFA).
Carbon monoxide (CO) is a separate danger. The CDC says more than 400 people in the U.S. die each year from unintentional CO poisoning not linked to fires, more than 100,000 visit an emergency department and over 14,000 are hospitalized (CDC).
Where should you install smoke alarms?
Put a smoke alarm inside every bedroom, outside each sleeping area and on every level of the home, including the basement. Mount alarms on the ceiling or high on a wall, following the manufacturer’s instructions. Keep them about 10 feet from cooking appliances to reduce nuisance alarms.
That placement comes from the USFA and the NFPA (USFA, NFPA). Your local building code may require more, especially if you remodel, so check with your local fire department or building department.
Which type of smoke alarm should you buy?
There are two basic sensor types. Ionization alarms and photoelectric alarms detect different kinds of fires. The USFA recommends that every home and sleeping area have both types, or dual-sensor alarms that combine them.
| Alarm option | What to know |
|---|---|
| Ionization | One of the two basic sensor types; the two types detect different kinds of fires |
| Photoelectric | The other basic sensor type; works best paired with ionization or as part of a dual-sensor unit |
| Dual-sensor | Combines both sensors in one unit, matching the USFA recommendation |
| Battery-only (9-volt) | Replace the battery at least once a year |
| Sealed 10-year battery | No battery swaps; replace the whole unit on the maker’s schedule |
| Hardwired with battery backup | Should be installed by a qualified electrician; replace the backup battery yearly |
| Strobe or bed-shaker | Uses flashing light or vibration for people who are deaf or hard of hearing |
If your home has older, stand-alone alarms, wireless interconnected models can be added without opening walls. Hardwired alarms are another option, but the USFA says only qualified electricians should install them. Our guide to hiring a contractor explains how to check an electrician’s license.
How do you test and maintain smoke alarms?
Press the test button on every alarm once a month. Replace 9-volt batteries at least once a year, and replace the backup battery in hardwired units yearly. Replace the whole smoke alarm 10 years after the manufacture date printed on it, even if it still beeps when tested.
Simple routine:
- Monthly: Press and hold the test button on each alarm until it sounds.
- Yearly: Replace replaceable batteries, and gently vacuum or dust the alarm.
- Every 10 years: Replace each smoke alarm. Check the date on the back when you move in.
Many households tie battery checks to clock changes in spring and fall. Our seasonal home maintenance checklist includes alarm testing alongside other recurring tasks.
What is carbon monoxide, and where does it come from?
Carbon monoxide is a colorless, odorless gas made when fuel burns. In homes, it can come from furnaces, gas water heaters, gas ranges, fireplaces, wood stoves, portable generators and vehicles running in an attached garage. Because you can’t see or smell it, a CO alarm is the only reliable way to detect it.
- 400DeathsMore than 400 a year, not linked to fires
- 100,000Emergency department visitsMore than 100,000 a year
- 14,000HospitalizationsOver 14,000 a year
Source: Centers for Disease Control and Prevention (as of October 18, 2026)
What are the symptoms of CO poisoning?
The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion as the most common symptoms (CDC). They are often described as “flu-like.”
Anyone can be poisoned, but the CDC says infants, older adults and people with chronic heart disease, anemia or breathing problems are more likely to get seriously ill.
Where should you install carbon monoxide alarms?
The CPSC says CO alarms should be installed on each level of the home and outside sleeping areas (CPSC). Don’t put them in attics or basements unless someone sleeps there. Choose battery-operated alarms or hardwired or plug-in alarms with battery backup, so they still work in a power outage.
| Task | Smoke alarms | CO alarms |
|---|---|---|
| Where to install | Inside each bedroom, outside sleeping areas, every level | Outside sleeping areas and on each level |
| Test | Monthly | Monthly |
| Replaceable batteries | At least once a year | Yearly |
| Replace the unit | 10 years after manufacture date | Maker's date, or about every 5 years |
Source: U.S. Fire Administration, CPSC and CDC (as of October 18, 2026)
CO alarm maintenance is a little different from smoke alarms:
- Test monthly, like smoke alarms. The CPSC recommends testing smoke and CO alarms monthly and replacing their batteries yearly.
- Replace on the maker’s schedule. The CDC says to replace CO detectors according to the manufacturer’s instructions or about every five years.
- Consider combination units. Combination smoke and CO alarms are available, the CPSC notes, but you’ll still need extra smoke alarms inside bedrooms.
How to prevent CO problems
The CDC recommends these habits:
- Have your furnace, water heater and any other gas, oil or coal appliances serviced by a qualified technician every year.
- Have chimneys inspected or cleaned every year.
- Run portable generators outside, more than 20 feet from windows, doors and vents, and never in a garage.
- Never run a car or truck in an attached garage, even with the door open.
- Never burn charcoal indoors or use camp stoves inside.
Winter is the highest-risk season for many homes, because heating systems run constantly and people use generators during outages. See our guide to winterizing your home for a full cold-weather checklist.
Do you need a fire extinguisher at home?
A small multipurpose extinguisher is a useful backup for very small fires, but getting out safely always comes first. The USFA says to use one only if the fire is small and contained, everyone has been alerted, someone has called the fire department, and you have a clear escape route.
The USFA explains extinguisher classes this way: Class A for ordinary items like wood and paper, Class B for flammable liquids like grease and oil, and Class C for electrical equipment (USFA). Multipurpose “A-B-C” extinguishers, sold at most home improvement stores, cover most common home fires. Look for a UL or ULC listing label.
To use one, remember PASS:
- Pull the pin, with the nozzle pointed away from you.
- Aim low, at the base of the fire.
- Squeeze the lever slowly and evenly.
- Sweep the nozzle from side to side.
Keep the extinguisher where you can reach it quickly, and check it regularly. Make sure the pressure gauge isn’t too high or too low, and look for dents, rust or a damaged hose. The USFA says young children and older adults should not use fire extinguishers.
How do you make a home fire escape plan?
Draw a simple map of your home showing every door and window, find two ways out of every room, and pick an outside meeting place a safe distance from the house. Then practice a fire drill with everyone in the home at least twice a year, at different times of day.
Ready.gov recommends a home fire drill at least twice a year (Ready.gov). Steps from the USFA and Ready.gov:
- Sketch a floor plan and mark all doors and windows.
- Find two exits from every room, and keep them clear. For upstairs bedrooms, the second way out may be an escape ladder.
- Choose a meeting place outside, such as a mailbox or tree in front of the home.
- Start each drill by pressing a smoke alarm’s test button.
- Get out, go to the meeting place and practice calling 911 from outside.
- Teach everyone to feel a closed door with the back of a hand. If it’s hot, use the second way out.
How much does this cost, and how do you fit it into your budget?
Alarms are inexpensive compared with most home repairs. The USFA lists basic ionization or photoelectric alarms starting at about $6 and dual-sensor alarms starting around $24, with wireless interconnected models costing more. Add replacement dates to your home maintenance budget so a 10-year swap doesn’t come as a surprise. It’s also worth knowing what your homeowners insurance covers after a fire, but working alarms are what protect your family.
This guide is general safety information. Local fire and building codes may set specific requirements for your home, so check with your local fire department when in doubt.
Frequently asked questions
How many smoke alarms do I need?
At least one inside each bedroom, one outside each sleeping area and one on every level, including the basement. A two-story home with three bedrooms and a basement could easily need six or more. Local codes may require more, so check with your local fire department.
How often should I test smoke and CO alarms?
Test them once a month using the test button. Replace 9-volt batteries at least once a year, and replace the backup battery in hardwired alarms yearly. Sealed 10-year alarms don't need battery changes, but the whole unit must be replaced on schedule.
How long do smoke alarms last?
Replace smoke alarms every 10 years, counting from the manufacture date printed on the alarm, not the date you installed it. That applies to hardwired and battery alarms, including sealed 10-year models.
How long do carbon monoxide alarms last?
Follow the replacement date from the manufacturer. The CDC says to replace CO detectors according to the maker's instructions or about every five years.
What should I do if my carbon monoxide alarm goes off?
Get everyone, including pets, outside into fresh air right away and call 911. Don't go back inside until emergency responders say it's safe. If anyone has headache, dizziness, nausea or confusion, tell the dispatcher and get medical care.
Can I use a combination smoke and CO alarm?
Yes. The CPSC notes that combination smoke and carbon monoxide alarms are available. Just make sure you still have enough alarms in the right places, because smoke alarms are needed in more locations, such as inside each bedroom.
Where should I not put a smoke alarm?
Keep smoke alarms about 10 feet from cooking appliances to cut down on false alarms, per NFPA guidance. Don't install CO alarms in attics or basements unless someone sleeps there, the CPSC says. Always follow the maker's mounting instructions.
Should I fight a home fire with an extinguisher?
Only if the fire is small and contained, everyone is alerted, 911 has been called and you have a clear way out. Otherwise, get out and stay out. The USFA says young children and older adults should not use fire extinguishers.
Sources
We check every source on the date shown. Rules and figures change, so confirm current details with the agency.
- Smoke Alarms · U.S. Fire Administration · accessed
- Learn More About Smoke Alarms · National Fire Protection Association · accessed
- Smoke Alarms in US Home Fires (June 2024) · National Fire Protection Association · accessed
- Carbon Monoxide Poisoning Basics · Centers for Disease Control and Prevention · accessed
- CO Alarms · U.S. Consumer Product Safety Commission · accessed
- Choosing and Using Fire Extinguishers · U.S. Fire Administration · accessed
- Home Fire Escape Plans · U.S. Fire Administration · accessed
- Practice Your Home Fire Escape Plan · Ready.gov · accessed
About the author
The Homeowner Guide Editorial Team
Our editorial team researches every guide from primary sources such as the IRS, FEMA, the CFPB, the FTC, state insurance departments and county assessors, and updates each article when the rules change.
