Menu Close

Where Must Carbon Monoxide Alarms be Located in the Home?

Have you ever wondered how many carbon monoxide alarms you need installed throughout your home or where they need to be located?

Section R315 of the International Residential Code (IRC) details the requirements for carbon monoxide alarms within residential dwelling units.

Fun Tip: To learn the difference between the International Residential Code (IRC) verses the International Building Code (IBC), be sure to check out this POST.

Carbon Monoxide alarms have a huge role of alerting occupants of potential CO gas that might be present in the home. Carbon Monoxide (CO) is a toxic gas that is odorless and colorless. This type of gas is impossible to see, taste or smell and can kill occupants before they are aware it is present.

Therefore it is important to have a detection device that would notify you of potential CO and give you an opportunity to get to safety without much delay.

In this post we will cover where carbon monoxide alarms are required to be located within a residential dwelling unit per the requirements of the International Residential Code (IRC).

Carbon Monoxide Alarm Locations

Where should carbon monoxide alarms be located?

Per Section R315.3, Carbon Monoxide alarms are required to be placed in the following locations:

Carbon monoxide alarms in dwelling units shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms. Where a fuel-burning appliance is located within a bedroom or its attached bathroom, a carbon monoxide alarm shall be installed within the bedroom.

Carbon Monoxide Alarms Outside Bedrooms

The first part of the code section requires that carbon monoxide alarms be located outside each sleeping area throughout the house in the immediate vicinity of the bedrooms.

This is similar to one of the locations where smoke alarms are required to be placed. Both alarms can be located near each other as long as they are installed per the manufacturers installation instructions.

Carbon Monoxide Alarms Inside Bedrooms

The second part of the code section requires carbon monoxide alarms to be placed inside a bedroom whenever a fuel-burning appliance is located within the bedroom. Since a fuel-burning appliance is one of the sources where CO can be present, the code requires a carbon monoxide alarm be installed in a sleeping room that would contain one.

For example this would be appliances such as a gas furnace, wood fireplace, gas water heater, etc…

Such type of appliances located in a bedroom will require a carbon monoxide alarm be installed.

The code section continues by stating that a carbon monoxide alarm is still required in a bedroom when an attached bathroom serving the bedroom has a fuel-burning appliance installed in it.

Even though the bedroom might not contain a fuel-burning appliance, if the attached bathroom contains one, then the code requires the bedroom to still have a carbon monoxide alarm installed.

As you can see, Section R315.3 specifies the locations of were carbon monoxide alarms are required to be installed throughout the dwelling unit.

It is important to note that you may be thinking of why the code does not include attached garages since automobile exhaust can be a source of CO, however the reason for this is clear. Section R302.5 clearly says that an opening between a garage and a room used for sleeping purposes is NOT permitted.

To read more about Fire Rated Door Requirements Between a Garage and House, be sure to check out THIS POST.

So this sums up the basic code requirements for residential carbon monoxide alarm locations.

For more information regarding detailed requirements of carbon monoxide alarms within residential dwelling units, be sure to check out Section R315 of the 2018 International Residential Code (IRC).


* Reference Source – 2018 International Residential Code – [Buy on Amazon]

Want to become a Residential Plans Examiner?

Test your knowledge with 2 full practice exams based on the Residential Plans Examiner Exam & 1 Plan Review Test.


Includes 2 Practice Exams, 60 Questions Each, & 1 Plan Review Test, 30 Questions

This practice exam is designed for those who are looking to take the 2015 or 2018 R3 Residential Plans Examiner Certification Exam administered through the International Code Council (ICC).

These practice exams are intended to help you prepare for the actual exam by helping you navigate through the code book to familiarize yourself with the specific code sections. They will test your knowledge on the exam content areas covered to improve your chances of passing the certification exam. This is a great way to prepare yourself for the actual exam administered by ICC.