How Long Do Smoke Detectors Last?

Next steps (at a glance)

If you only do 3 things:

  1. Check the manufacture date on each smoke detector.

  2. Replace any unit that is 10 years old or older.

  3. Test detectors monthly and replace batteries as needed.

Urgency level: Low → Medium
(Becomes High if alarms fail to test, chirp repeatedly, or are missing in key areas.)

Short answer

Most smoke detectors should be replaced every 10 years, even if they still beep or appear to work. Sensors degrade over time and become less reliable as they age.

A detector that powers on is not the same as a detector that can still detect smoke accurately.

What a smoke detector does (and why it matters)

Smoke detectors sense particles from fires and trigger an alarm to alert occupants early. Early warning is critical—most injuries and fatalities occur from smoke inhalation, not flames.

Because detectors sit quietly for years, it’s easy to assume they’re working when they’re not.

Typical smoke detector lifespan (what most homes see)

  • Smoke detectors (all types): replace at about 10 years
    Replacement clues: yellowing plastic, frequent false alarms, failed tests

  • Batteries: replace as needed (often annually)
    Replacement clues: chirping sounds, weak or no alarm during test

Even hard-wired detectors have internal sensors that age.

What shortens smoke detector effectiveness

  • Age and sensor degradation

  • Dust, debris, or insects inside the unit

  • High humidity or steam exposure

  • Improper placement near kitchens or bathrooms

  • Long periods without testing

Detectors don’t usually fail all at once—they become less sensitive over time.

Warning signs a smoke detector needs attention

  • Repeated chirping or beeping

  • Failure during test button checks

  • False alarms without obvious cause

  • Discoloration or cracking of the housing

  • Detectors older than 10 years

Any detector that fails a test should be addressed immediately.

What happens if old detectors aren’t replaced

  • Delayed or missed alarms during a fire

  • Reduced warning time for occupants

  • Increased risk during sleeping hours

  • False sense of security

Outdated detectors often look fine but respond too slowly when it matters.

DIY-safe checks you can do

These steps are safe for homeowners:

  • Press the test button monthly

  • Replace batteries when chirping occurs

  • Gently vacuum vents to remove dust

  • Check the manufacture date on the back of the unit

Do not open sealed detectors or attempt sensor repairs.

Maintenance that actually helps

  • Monthly testing confirms the alarm still sounds

  • Battery replacement prevents nuisance chirping

  • Unit replacement at 10 years ensures reliable detection

  • Occasional dust removal keeps sensors clear

Testing confirms sound, not sensor accuracy—age still matters.

If you don’t want to call a professional yet but want to stay safe

Prioritize these:

  • Replace detectors older than 10 years

  • Install fresh batteries if chirping occurs

  • Make sure detectors are present in key areas (sleeping areas, hallways, each level)

If alarms continue to malfunction, replacement is safer than troubleshooting.

Common mistakes

  • Assuming a working beep means a working sensor

  • Ignoring the manufacture date

  • Removing batteries to stop chirping

  • Keeping outdated detectors because they “still work”

Detectors are safety devices, not lifetime fixtures.

When to call a professional

Consider professional help if:

  • Detectors are hard-wired and malfunctioning

  • Multiple alarms trigger without cause

  • You’re unsure proper placement requirements

What to ask:

  • Whether replacement or rewiring is needed

  • Compatibility with existing systems

What to expect:
Most replacements are straightforward. Costs vary based on wiring and quantity.

Related guides

Disclaimer:
This is general information only. When in doubt, hire a licensed professional.