Fire Side Chat: More of What You Need to Know About CO

The heightened attention given to CO detection in recent years is reflected in updates to the International Residential Code and NFPA 720. Learn what these changes are, their importance, and when and where not to apply them.

For a number of years, carbon monoxide (CO) alarms and detectors have been required to be installed within various occupancy classifications by a number of state laws and local ordinances. It was not until publication of the 2009 edition of the International Residential Code (IRC) by the International Code Council (ICC) that CO alarms were required to be installed within all single-family residential occupancies.

This month, we pick up where we left off last time when we discussed the various methods that may be used for monitoring CO detectors (see “CO: Stopping a Silent Killer). We’ll look at the changes within the IRC and National Fire Protection Association (NFPA) 720 detector siting requirements, among other important CO considerations.

Mind IRC as Well as State/Local Codes

The following CO requirement was added to the IRC:

R315.1 Carbon monoxide alarms — For new construction, an approved carbon monoxide alarm shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms in dwelling units within which fuel-fired appliances are installed and in dwelling units that have attached garages.

The IRC also has a requirement for CO alarms to be installed if work is performed that has a value greater than $1,000 and involves a permit being issued:

R315.2 Where required in existing dwellings —Where work requiring a permit occurs in existing dwellings that have attached garages or in existing dwellings within which fuel-fired appliances exist, carbon monoxide alarms shall be provided in accordance with Section R315.1.

While R315.2 is a retroactive requirement, there is a construction threshold before CO alarms are required to be installed. States such as California have, through legislative action, passed laws that add a retroactive component that mandates CO alarms be provided in all single-family occupancies within a stated timeframe, regardless if permitted work is being performed or not.

The system installer should be familiar with their state and local requirements for CO alarms and detection systems. Not all states have adopted the 2009 edition of the IRC; however, a number of them still have laws in place that require CO alarms and detection systems. One valuable source for information on the requirements found within each state can be accessed on System Sensor’s Web site (

Depending on the state and its requirements, there may be specified locations within an occupancy the CO alarm or detector is to be mounted. The installer should be familiar as to any codified locations for CO detection for the region in which the work is being performed.

NFPA 720 Spells Out How to Install

The IRC and the various adopted state codes, however, are not an installation standard. The installation standard for CO alarms and detectors is NFPA 720, Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment. NFPA 720 is comprised of nine chapters and three annexes (see sidebar); some of Chapter 7 was covered in May’s Fire Side Chat.

Anyone who installs CO detection systems needs to be familiar with the provisions contained within NFPA 720. A number of the requirements mirror those found within NFPA 72, National Fire Alarm Code. One section that is different is in regard to the mounting requirements of CO detection devices. This information is found in Chapter 5 for systems other than single-family occupancies, with those being detailed in Chapter 9.

As a number of states and local jurisdictions were calling for CO detection, the NFPA 720 Technical Committee was concerned there was no unified requirement for the mounting of devices. Previous editions of NFPA 720 referred to the manufacturers’ installation instructions for siting requirements. The Technical Committee wanted to avoid the various state and local requirements for CO also having unique mounting requirements. The committee was also concerned about the number of detection devices required.

In 1996, the National Fire Protection Research Foundation funded a paper, National Carbon Monoxide Detection Research Project, Detector Location: Literature Review and Test Planning (, which listed a number of sources of CO as well as how it is dispersed through a space.

In 2007, a second commissioned report, Development of a Technical Basis For Carbon Monoxide Detector Siting (, identified two uses for CO detection: 1) detectors in rooms containing a combustion source; 2) detectors located in occupied areas to provide monitoring of the air. (See sidebar for other sources of potential CO generation.)

The report concluded that CO detection devices installed in rooms that have a combustion source should have the detector sited proximate to the combustion device. The report further concluded that detectors placed near the floor could result in detection delays when prestratification effects of heat sources high in the space are considered. Detectors intended to provide monitoring of the air in occupied areas may be mounted throughout those sections of the building. These detectors should be installed in relatively open environments.

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About the Author


Shane Clary, Ph.D., is Security Sales & Integration’s “Fire Side Chat” columnist. He has more than 37 years of security and fire alarm industry experience. He serves on a number of NFPA technical committees, and is vice president of Codes and Standards Compliance for Pancheco, Calif.-based Bay Alarm Co.

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