To be considered up to code, all smoke alarms must bear the label of a recognized testing laboratory. They should be installed on every level of the business, including near stairways to the upper levels.
Smoke alarms should be at least ten feet from a cooking appliance to minimize false alarms while cooking is ongoing. Mount smoke alarms high on the walls or 12-inches away from the ceiling.
To ensure your smoke alarms remain up to code, never paint over them and test them regularly to ensure proper function at all times.