Smoke detector installation cost
Smoke detectors cost $80 to $200 per unit hardwired, or $15 to $60 for a battery unit you fit yourself. They also expire after ten years, whether or not they have ever detected anything.
National average
$150
per each
On this page
Installing smoke detectors costs $80 to $200 per unit for hardwired and interconnected alarms, or $15 to $60 for a battery unit you fit yourself. Doing a whole house of hardwired interconnected alarms is $400 to $1,500.
It is the cheapest life safety equipment in a house and the one most often left with a chirping battery removed.
What it costs
| Job | Typical cost |
|---|---|
| Battery smoke alarm, DIY | $15 to $60 |
| Ten-year sealed battery alarm, DIY | $25 to $70 |
| Combination smoke and CO alarm | $40 to $120 |
| Hardwired alarm, replacing an existing one | $80 to $200 |
| Hardwired and interconnected, new installation | $150 to $350 per unit |
| Whole house, 5 to 8 hardwired units | $400 to $1,500 |
| Wireless interconnected alarms, DIY | $40 to $100 per unit |
| Smart alarm with app notification | $100 to $250 per unit |
| Adding a circuit for hardwired alarms | $350 to $900 |
| Heat detector for a garage or attic | $50 to $150 |
Where they go
Requirements are consistent across most of the country:
- Inside every bedroom
- Outside each sleeping area, in the hallway serving the bedrooms
- On every level of the house, including the basement
- At the top of every stairway, and at the bottom of a basement stair
- Not in the kitchen, but within 10 to 20 feet of it, and preferably a photoelectric type at that distance to reduce cooking false alarms
- Not in a bathroom, and not within 3 feet of a bathroom door
- Not within 3 feet of an HVAC supply register or a ceiling fan
- On the ceiling where possible, or high on a wall no more than 12 inches from the ceiling
- Not in an unconditioned attic or garage, where temperature swings cause false alarms; use a heat detector there instead
Carbon monoxide alarms go outside each sleeping area and on every level with a fuel- burning appliance or an attached garage.
Ionisation, photoelectric, and why it matters
Photoelectric alarms respond faster to smouldering fires: upholstery, bedding, electrical fires in walls. These are the fires that kill people in their sleep.
Ionisation alarms respond faster to fast-flaming fires: a pan fire, a Christmas tree. They are also the type that goes off when you make toast, which is why they end up with the battery out.
Dual-sensor alarms contain both and are the sensible default.
If you buy one type, buy photoelectric. The false alarm rate is dramatically lower, which means it stays powered, which is the only thing that matters.
Interconnection is the upgrade that counts
Interconnected alarms all sound when any one detects. A fire starting in a basement sets off the alarm in the bedroom on the second floor, which is the difference between waking up and not.
Hardwired interconnection is standard in new construction. In an existing house, wireless interconnected alarms achieve the same thing without wiring: they talk to each other by radio, cost $40 to $100 each, and install like ordinary battery alarms.
For a house without hardwired alarms, a set of wireless interconnected units is the highest-value $300 anyone spends on it.
They expire
Smoke alarms have a service life of ten years and carbon monoxide alarms five to seven. The sensor degrades whether or not it has ever detected anything.
The manufacture date is printed on the back. If you have never looked at it, look today. Alarms fitted when a house was built and never replaced are extremely common and they are not working alarms; they are objects on a ceiling.
Batteries: annually for a replaceable-battery unit, or buy sealed ten-year lithium units and replace the whole alarm at the end.
Frequently asked questions
Can I fit them myself?
Battery and wireless interconnected units, yes, and it is a fifteen-minute job per alarm. Hardwired units replacing existing hardwired ones are a plug-in connector and a bracket, which is within reach for most people with the breaker off. A new hardwired circuit is an electrician.
Why does it chirp at 3am?
Low battery, and the chirp interval is temperature-sensitive, which is why it starts when the house cools overnight. It can also mean the alarm has reached end of life, which some units signal the same way.
Do I need CO alarms if I have no gas?
If there is an attached garage, yes. If everything is electric and there is no attached garage and no fireplace, the risk is low. They cost $40; most households fit them anyway.
Are smart alarms worth it?
The useful part is being told your house alarm is sounding while you are out, which a conventional alarm cannot do. Whether that is worth $150 a unit against $60 depends on whether the house is often empty.
How many do I actually need?
A three-bedroom two-storey house typically needs five to seven: one per bedroom, one in each hallway, one per level, one in the basement. Count the list above rather than guessing.
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