• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

When CO2 alarms are required

Mr. Inspector

SAWHORSE
Joined
Nov 28, 2009
Messages
4,695
Location
Poconos/eastern PA
.

CO2 alarms required in new construction only when there is a fuel-fired appliance. But CO2 alarms are required for any permit for alterations, repairs, additions or when bedrooms are added even when there is no fuel-fired appliance on the inside of a existing house. But as you can see a CO2 is not required if just a new mechanical system is installed or repaired, fuel-fired or not, in an existing house per exception.

According to the code per definition, a fireplace is a Mechanical System so if a permit is only for a fireplace a CO2 alarm is not required:
MECHANICAL SYSTEM. A system specifically addressed
and regulated in this code and composed of components,
devices, appliances and equipment.

2015 IRC:
R315.2 Where required. Carbon monoxide alarms shall be
provided in accordance with Sections R315.2.1 and R315.2.2.
R315.2.1 New construction. For new construction, carbon
monoxide alarms shall be provided in dwelling units
where either or both of the following conditions exist.
1. The dwelling unit contains a fuel-fired appliance.
2. The dwelling unit has an attached garage with an
opening that communicates with the dwelling unit.
R315.2.2 Alterations, repairs and additions. Where
alterations, repairs or additions requiring a permit occur,
or where one or more sleeping rooms are added or created
in existing dwellings, the individual dwelling unit shall be
equipped with carbon monoxide alarms located as
required for new dwellings.
Exceptions:
1. Work involving the exterior surfaces of dwellings,
such as the replacement of roofing or siding,
or the addition or replacement of windows or
doors, or the addition of a porch or deck, is
exempt from the requirements of this section.
2. Installation, alteration or repairs of plumbing or
mechanical systems are exempt from the requirements
of this section.

So say a new house was just finished, built with no CO2 alarm required or installed.
A permit for this house just for a new fireplace or a fire-fueled mechanical system does not need a CO2 alarm.
But a permit for this house just for a new electrical circuit will need require a CO2 alarm.

I'm I interpreting this right?
 
You are getting your

“O”

And

“2”

Mixed up. Houses normally do not have CO2, except for the heavy beer drinkers.
 
No...you are not interpreting the code correctly. But that’s only because I have a different interpretation.
 
Last edited:
I would permit a new fireplace as an alteration, and not as mechanical equipment. It is mechanical equipment, but you can't install it without an alteration to the house, so therefore = an alteration. I would require a CO detector.

Does this house not have an attached garage? How many houses are built nowadays without one?
 
R315.2.1 Existing buildings and new construction. For existing buildings and new construction, carbon monoxide alarms shall be provided in dwelling units where either or both of the following conditions exist.
  1. The dwelling unit contains a fuel-fired appliance or fireplace.
  2. The dwelling unit has an attached garage with an opening that communicates with the dwelling unit.
One would think that this covers all possibilities. An existing or newly constructed dwelling that has a fuel fired appliance, fireplace or attached garage that has an opening into the dwelling shall have a CO alarm. I don't see the need for the phrase "new construction" in as much as it to would qualify as existing as soon as it existed.

However, apparently one would be wrong about R315.2.1 covering all possibilities. That's because there is a R315.2.2.

R315.2.2 Alterations, repairs and additions. Where an addition is made to an existing dwelling, or a fuel-burning heater, appliance, or fireplace is added to an existing dwelling, not previously required to be provided with carbon monoxide alarms, new carbon monoxide alarms shall be installed in accordance with Section R315.

This section does not make sense and should be removed. It serves no purpose. But that's California code as we know it.

I use R315.2.1 like it's a Capitol One credit card......it works every time, everywhere.
 
Last edited:
2012 IRC
R315.3 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.

When we move to the 2018 editions I will not be aware of the exception for plumbing and mechanical system repair or replacement since the contractors have been trained to provide and install CO detectors when they change out a water heater and/or furnace. Since they do not read the IRC they will never know about the exception
 
I would permit a new fireplace as an alteration, and not as mechanical equipment. It is mechanical equipment, but you can't install it without an alteration to the house, so therefore = an alteration. I would require a CO detector.

Does this house not have an attached garage? How many houses are built nowadays without one?

I meant a fireplace that does not need any structure work like a self standing fireplace, wood stove/fireplace with just a vent or even a gas insert
 
shall be equipped with carbon monoxide alarms located as required for new dwellings.

The key is that they are as required for new dwellings. If new dwellings do not require, than neither would the alteration.
 
The key is that they are as required for new dwellings. If new dwellings do not require, than neither would the alteration.

Don't just take part of the sentence: I think the word located is also a key

R315.2.2 Alterations, repairs and additions. Where
alterations, repairs or additions requiring a permit occur,
or where one or more sleeping rooms are added or created
in existing dwellings, the individual dwelling unit shall be
equipped with carbon monoxide alarms located as
required for new dwellings.


R315.3 Location. 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.
 
Most states have other laws, have additional retroactive requirements.
The Building code does not contain all the laws and codes that must be enforced.


  • California: Cal. Health & Safety Cod17926(a), Retroactively Mandatory in each dwelling unit as following this applicable time period:
  • For all existing single-family dwelling units on or before July 1, 2011.
  • For all other existing dwelling units, duplex/apartment/condominium complex, on or before Jan. 1, 2013.
  • The Carbon Monoxide Poisoning Prevention Act of 2010 mandates that detectors must be installed if the residential unit has any of the following:
    • Gas appliances such as gas stove, fireplace, gas water heater, etc.
    • Fireplace.
    • An attached garage.
  • January 1, 2013, all multi-family units are required to install Carbon Monoxide detectors.
  • Washington State law (RCW 19.27.530) requires carbon monoxide alarms to be installed in new residences. As of January 1, 2013, carbon monoxide alarms are required in existing apartments, condominiums, hotels, motels, and single-family residences, with some exceptions. Owner-occupied single-family residences, legally occupied before July 26, 2009, are not required to have carbon monoxide alarms until they are sold.
 
Last edited:
Dwelling units for rent in Montana
(h) shall install in each dwelling unit under the landlord's control an approved carbon monoxide detector, in accordance with rules adopted by the department of labor and industry, and an approved smoke detector, in accordance with rules adopted by the department of justice. Upon commencement of a rental agreement, the landlord shall verify that the carbon monoxide detector and the smoke detector in the dwelling unit are in good working order. The tenant shall maintain the carbon monoxide detector and the smoke detector in good working order during the tenant's rental period. For the purposes of this subsection, an approved carbon monoxide detector, as defined in 70-20-113, and an approved smoke detector, as defined in 70-20-113, bear a label or other identification issued by an approved testing agency having a service for inspection of materials and workmanship at the factory during fabrication and assembly.
 
Back
Top