Smoke Alarm Basics
Homes Built in 1998 or Later
If your home was built in 1998 or later, codes require that there are smoke alarms in common areas on each level of the home, and in each bedroom. The updated code also requires that smoke alarms have a battery backup in case of a power failure.
The alarms are "interconnected", meaning that they communicate with each other via an extra wire in the system. If one alarm senses smoke, it alerts the entire system. If your house is ten years old or older, and you have the original alarms, it's time to replace your system.
Homes Built Before 1998
Alarms, typically, were only installed in common areas on each floor.
In most cases, alarms did not include a battery backup. If you still have your original alarms, you are past-due to replace them with newer alarms.
No matter what kind of smoke alarm you have, most manufacturers recommend replacing your smoke alarm when it is ten years old.
Types of Alarms