Where are smoke alarms required after a renovation?

Work it through

You're the contractor. Pick what you'd do, then see how each choice plays out.

1. AThe new bedroom needs its own smoke detector, and if the existing detectors are battery-only, the renovation triggers a requirement to install interconnected, hardwired detectors. Explain the code and include it in the work
   Correct

   IRC R314 requires smoke alarms in each sleeping room, outside each sleeping area, and on each floor level. New construction and renovations require hardwired, interconnected detectors with battery backup. Adding a bedroom to an existing home through renovation triggers the upgraded requirements for the new work. The cost is minimal and the life-safety value is immense.

2. BThey have detectors already — that's enough. No need to add cost for one more
   Wrong

   A new bedroom requires a smoke detector inside the room, not just in the hallway. IRC R314 is specific about locations: inside each bedroom, outside the sleeping area, and on every floor level. Renovations adding bedrooms must comply with current code for the new work. The inspector will check for this. A smoke detector costs $15. Not installing one in a new bedroom is a code violation with life-safety implications.