Smoke and CO alarm placement

Smoke alarm locationsR314.3#

Smoke alarms are required in every sleeping room, in the hallway or area immediately outside each sleeping area, and on every story of the dwelling including basements.

In split-level construction without an intervening door, a single smoke alarm on the upper level serves both levels if the lower level is less than one full story below.

InterconnectionR314.4#

All smoke alarms in new construction must be interconnected so that activation of one triggers all. Interconnection may be hardwired or, where permitted, wireless using a listed system.

Power sourceR314.6#

Smoke alarms in new construction must receive primary power from the building wiring with a secondary battery backup. Battery-only alarms are not acceptable for new work.

Alarms added to an existing dwelling during a renovation may use batteries when hardwiring is impractical. Check with the local inspector on what counts as impractical.

CO alarmsR315#

Carbon monoxide alarms are required outside each sleeping area in dwellings that contain a fuel-burning appliance or that have an attached garage.

CO alarms may be combined with smoke alarms in a single listed combination device. Placement rules for the combination device follow the smoke alarm rules above.

Common inspection flags#

Frequent failure points:

• Smoke alarm missing from one sleeping room in a multi-bedroom renovation
• Alarms not interconnected when the scope of work triggers interconnection
• Battery-only alarms in new construction
• CO alarm missing in a home with an attached garage
• Alarms installed within the dead-air space at a ceiling-wall junction