Smoke detectors should be installed on each level in your home as well as outside sleeping areas. If you live in a smaller home, one on each level will usually take care of it. Don’t forget the attic and basement. Smoke detector placement locations should also be considered.
You want to allow your smoke detector to have ample air flow so never place it in dead air space. They should be mounted to the ceiling at least 8-12 inches from any adjacent wall. Also avoid areas where smoke may normally exist, like kitchens and avoid mounting your smoke alarm close to a bathroom. Steam and moisture can destroy the metal within the detector.