According to the National Fire Protection Association (NFPA), minimum protection requires a smoke detector outside each sleeping area and on every level of the home, including the basement.
Smoke Detector Placement
On floors without bedrooms, detectors should be installed in or near living areas such as dens, living rooms, or family rooms. For extra protection, the NFPA suggests installing additional detectors in dining rooms, furnace rooms, utility rooms, and hallways.
Smoke detectors are not recommended for kitchens, bathrooms, or garages - where there are cooking fumes or steam. Attics and other unheated spaces - where humidity and temperature changes might affect a detector's operation.
Hear the Alarm
Be sure everyone sleeping in your home can hear your smoke detectors' alarms even with bedroom doors closed. If not, or if any residents are hearing- impaired, install additional detectors inside bedrooms. For the hearing impaired, there are smoke detectors that flash a strobe light in addition to sounding an audible alarm.