What carbon monoxide alarm means
A carbon monoxide alarm senses the odorless gas from fuel burning appliances, attached garages and blocked vents and sounds an alarm.
Also called CO detector, CO alarm.
Where it matters on a home inspection job
HVAC techs should check for CO alarms on every fuel appliance call. Required locations depend on local code, and combination smoke and CO units simplify the install.
What the model code says
- Carbon monoxide alarms go outside each separate sleeping area near the bedrooms, and inside a bedroom that contains a fuel-burning appliance. (IRC 2021, Chapter 3)
Check which code edition your building department enforces for carbon monoxide alarm before you quote.
What it costs
Koira's smoke detector installation cost guide puts a typical job at $110, with most between $70 to $150. The guide shows its sources and what moves the price.
Work it out
- Cost guide: Smoke detector installation cost
- Tools, templates and guides: Free home inspection resources
Sources: 2021 International Residential Code, Chapter 3, Building Planning (ICC). Checked October 9, 2026.