National price ranges
Fixr: $70 to $150 per hardwired dual-sensor alarm installed; $20 to $40 for the alarm alone.
When it is worth it
- Any level or bedroom without a working alarm.
- Alarms older than 10 years (check the date on the back).
- Gas appliances, a fireplace or an attached garage with no CO alarm.
What moves the price
- Hardwired versus sealed 10-year battery units.
- Wiring between floors for interconnection.
- Combination smoke and CO units.
DIY or hire it out
Battery alarms with sealed 10-year batteries are DIY; many wireless models interconnect without wiring. Test monthly.
Tax note. IRS Publication 502 lists this among home changes that usually do not raise a home's value, so the cost can count as a medical expense if you itemize and total medical costs pass 7.5% of adjusted gross income:
Modifying fire alarms, smoke detectors, and other warning systems.
(IRS Publication 502, 2025)
Where this shows up in the home check
Keepstead suggests this fix when one of these checks fails. Run the home check to see whether it is a priority for your home.
- There is a working smoke alarm inside the bedroom (bedroom)
- There are smoke alarms on every level and outside each sleeping area, tested monthly (lighting, electrical and alarms)
- Smoke alarms are interconnected, so when one sounds they all sound (lighting, electrical and alarms)
- No smoke alarm is more than 10 years old (check the date on the back) (lighting, electrical and alarms)
- There is a carbon monoxide alarm on each level if the home has gas, a fireplace or an attached garage (lighting, electrical and alarms)
Frequently asked questions
Where do smoke alarms go?
USFA: in every bedroom, outside each separate sleeping area, and on every level including the basement.
Where do CO alarms go?
CPSC: on each level of the home and outside sleeping areas, with battery power or battery backup.
Guidance sources
- U.S. Fire Administration (FEMA): Smoke Alarms (accessed 2026-10-17)
- U.S. Consumer Product Safety Commission: CO Alarms (accessed 2026-10-17)