Fire code
requirements.
If a fire inspector has asked about the carbon monoxide system in your garage, or you are trying to work out what you are actually obligated to do, this page covers the three rules that matter and what each one means in practice.
1. Your gas detection system must be inspected and tested at least once a year
California Fire Code Section 916.11 states that inspection and testing of gas detection systems shall be conducted not less than annually, that sensor calibration shall be confirmed at the time of sensor installation, and that calibration shall be performed at the frequency specified by the sensor manufacturer.
Two things follow from that wording. Annual is the floor, not the ceiling: if your sensor manufacturer specifies calibration every six months, six months is your requirement. And the obligation is ongoing. A system that passed at installation is not a system that is compliant today.
2. Enclosed garages must be ventilated, and CO monitoring is what lets you stop running the fans continuously
Building code requires mechanical ventilation for enclosed parking garages (IBC 406.4.2, with the mechanical requirements in the IMC). Those systems must either run continuously or be operated automatically by carbon monoxide detection. That second option is the entire reason CO monitoring systems exist in garages: without one, the fans run around the clock. With a properly calibrated one, they run only when vehicle exhaust actually requires it. See how gas detection works in an enclosed parking garage.
The practical consequence: if your CO system is out of calibration or failed, you are not only out of compliance, you are also either running fans you do not need or, worse, not running them when you do.
3. There is a legal exposure limit for the people in the building
Cal/OSHA sets the permissible exposure limit for carbon monoxide at 25 ppm as an 8-hour time-weighted average, with a 200 ppm ceiling (Title 8 Section 5155, Table AC-1). Anywhere staff work, including a parking structure, that limit applies. A monitoring system that is not reading accurately cannot demonstrate that you are under it. More on this in what Cal/OSHA 5155 means for a parking garage.
What about Title 24 and CO2?
Title 24 is California’s building standards code, and the fire code above is part of it (Part 9). Ventilation and energy provisions in Part 6 also affect how garage fans are controlled. Separately, a note on terminology, because it comes up constantly: if you are searching for CO2 sensors in a parking garage, you almost certainly mean CO. Carbon dioxide sensors are used for indoor air quality in occupied spaces. Carbon monoxide is the one that comes out of a tailpipe, is the one that is dangerous, and is the one the fire code is talking about.
Who is responsible
The building owner. Not the tenant, not the maintenance vendor, not the company that installed the system a decade ago. If an inspector asks for records, or something goes wrong and a claim follows, the maintenance history of that system is the document that matters.
Parking garage gas compliance checklist
On paper, gas compliance for a parking garage comes down to four things you can hand an inspector:
- An annual inspection and test of the full system, sensors and ventilation response together
- Calibration with certified span gas on the manufacturer’s schedule
- A dated service report listing every sensor, its readings, and any fault found
- Records available when the fire department, an insurer, or an attorney asks
ACES Monitoring does gas monitoring and nothing else, in enclosed parking garages, warehouses and commercial structures nationwide. If you are not sure whether your system has ever been calibrated, that is the normal state of affairs and it is the thing we are usually called about first.
Sources: California Fire Code §916.11 · IBC §406.4.2 and IMC ventilation provisions · Cal/OSHA Title 8 §5155, Table AC-1.
Common questions
Are CO detectors required in parking garages?
Enclosed parking garages must be mechanically ventilated, and the ventilation must either run continuously or be operated automatically by carbon monoxide detection (IBC 406.4.2 with the mechanical code provisions). Where a gas detection system is installed, California Fire Code 916.11 requires it to be inspected and tested at least annually.
How often does fire code require CO system testing?
California Fire Code 916.11 requires inspection and testing of gas detection systems not less than annually. Sensor calibration must be performed at the frequency specified by the sensor manufacturer, which is typically every 6 to 12 months.
Who is responsible for CO system maintenance in a rental building?
The building owner. Responsibility does not transfer to a tenant, a maintenance vendor, or the company that originally installed the system.
Is it CO or CO2 in a parking garage?
Carbon monoxide (CO). Carbon dioxide (CO2) sensors are used for indoor air quality in occupied spaces. CO is what comes out of a vehicle tailpipe, is the dangerous gas in an enclosed garage, and is what the fire code addresses.
Talk to a gas monitoring specialist
Tell us the building and how many sensors you have. We will tell you what service it needs and what it costs, no pressure.