A key argument used by opponents of residential sprinklers is that smoke alarms are sufficient for residential life safety. Sprinkler supporters reply by saying that smoke alarms can only warn occupants of a fire, while sprinklers will control a fire and give occupants time to escape.
That limitation is obviously correct. But both sides neglect another, and perhaps more important, limitation of residential smoke alarms – their reliability. Manufacturers will tell you that smoke alarms experience a three percent annual failure rate. By the time that they are 15 years old, they have nearly a 50-50 chance of failing to operate in a fire. That is why smoke alarm manufacturers recommend replacing them every 10 years.
Per the US Fire Administration, the number of homes with smoke alarms exceeded 90 percent in the 1990's. Some homeowners may faithfully replace the batteries in their smoke alarms, but I suspect that they do not buy new smoke alarms every 10 years. The continued use of smoke alarms that are beyond their life span is a likely factor in why over 50 percent of homes where fires occurred had smoke alarms with batteries installed, and yet failed to operate.
Sprinkler opponents who fail to note the reliability issue are selling a false sense of security to decision makers and the public. Sprinkler supporters need to include the reliability issue when pointing out the limitations of smoke alarms.