In each sleeping room.
Outside each separate sleeping area in the immediate vicinity of the bedrooms.
On each additional story of the dwelling, including basements, but not including crawl spaces and uninhabitable attics.

In dwellings or dwelling units with split levels and without an intervening door between adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided the lower level is less than one full story below the upper level.

When more than one smoke alarm is required to be installed within an individual dwelling unit, the alarm devices shall be interconnected in such a manner that the actuation of one alarm will activate all of the other alarms in the individual unit. The alarms shall be clearly audible in all bedrooms over background noise levels with all intervening doors closed. All smoke alarms shall be listed and installed in accordance with the provision of the Building Code and the Household Fire Warning Equipment Provisions of NFPA 72.

Other Occupancies

In addition to new construction of one- and two-family dwellings and townhouses, smoke alarms will be required in:

One- and two-family dwellings and townhouses undergoing alterations or additions.
Group R-4 small residential care/assisted living facilities (3-16 residents, excluding staff).
R-1 Bed and Breakfast establishments.

Smoke Alarm Options

Combination CO and smoke alarms may be used to satisfy the requirements for smoke and CO alarms.

Combination units may be interconnected with the smoke detectors within each dwelling unit.

Interconnected combination and CO detectors must be compatible with the smoke alarms used and installed per manufacturer's installation instructions.

R313.1.1 Alterations and additions.¹ When alterations or additions requiring a permit occur, or when one or more sleeping rooms are added or created in existing dwellings, the entire dwelling shall be provided with smoke detectors located as required for new dwellings. The smoke detectors shall have a power source in accordance with Section R313.2.

Exceptions:

1. The smoke detectors may be battery operated and are not required to be interconnected when other remodeling considerations do not require the removal of the appropriate wall and ceiling coverings to facilitate concealed interconnected wiring.
2. Alterations to the exterior surfaces of dwellings including, but not limited to, re-roofing, re-siding, window replacement and the construction of decks without roofs, are exempt from the requirements of this section.