The use of smoke detectors in a house can improve the odds of surviving a house fire by over fifty percent, but the number and placement of the alarms is just as important as having them to begin with. Most people who die in fires succumb to smoke inhalation long before flames can reach them.

A Little History on Smoke Detectors

When smoke alarms were first introduced in the 1970s, it was recommended that they be placed in, or just outside of bedrooms in the house.  The theory was that smoke reaching a bedroom when the occupants were asleep would trigger the alarms, wake the sleepers and enable them to escape. This recommendation meant that in two storey houses, smoke detectors were deployed on the second floor only where bedrooms are generally located in these homes.Home Smoke Detector

 It soon became apparent that in multi-storey homes, fires often reached deadly proportions before smoke could make its way up staircases to activate bedroom alarms.  Then too, closed doors on bedrooms also kept smoke from activating the alarms as early as they might if occupants slept with doors open.  Seconds matter in the successful evacuation from a burning home therefore the earlier the alarm activates the better chances for survival.

 Building codes soon required that smoke alarms be placed on each story of multi-story homes. However, this did not solve all the problems associated with their use.

Smoke alarms positioned inside bedrooms, (especially those with televisions or heating sources that might catch fire, and in the homes of smokers who habitually light up in bed) are most effective for alerting for fires begun inside a bedroom.  For fires originating outside of sleeping areas, bedroom doors are barriers to smoke. This can allow for a few more minutes of survival in some circumstances, but in others can prevent a timely activation of a smoke alarm.

 Federal recommendations altered in the 1980s, suggesting that smoke alarms be placed just outside bedroom doors. This gave early warning if a fire originated elsewhere in the house and if the occupants of the bedroom slept with their doors open, also provided protection from in-bedroom fires.

There are some places where fires can originate that are not suitable for fire alarms at all however.  Alarms positioned in kitchens seem like fundamental common sense, but as anyone can attest who has ever had fumes from cooking set off a fire alarm repeatedly, often defeat the purpose. More than one battery has been removed from a smoke detector (or been allowed to run down and not be replaced) by such false alarms. 

Garages are another area where smoke alarms are not recommended, as car exhaust can trigger the alarms.  Unheated attics and crawlspaces often suffer an extreme range of temperatures, either too cold or too hot that can interfere with electronic mechanisms in the detectors.   These areas are usually adequately served by smoke detectors elsewhere in the house, even when fires begin in these places. Other types of alarms can be placed in these areas, heat detectors are especially effective, but should not replace smoke alarms in the home.

So how many Smoke Detectors should a home have?

At least one for each storey of the house is important, and alarms should be placed in the hallways outside of each bedroom in the home especially if sleeping areas are not clustered together. It may also be advisable to place a smoke alarm in entertainment rooms where a high number of electronics are housed, or in living rooms with elaborate television and music systems are often placed; If not in the rooms themselves, then in hallways adjacent.

What is also important is that however many alarms you do have, that they are functional!  According to statistics compiled by the federal government, at any given time, up to a third of all smoke detectors in homes nationwide are non- functioning. Most smoke detectors are battery operated and the biggest cause of non functioning alarms is dead batteries.  It is recommended that alarms be tested every month, and that a day each year be chosen when batteries are routinely replaced.   A government recommendation for many years has been that this change of battery day coincide with time changes or New Years Day.  In homes where smoke detectors are powered by the home’s electrical circuits, it is advisable to supplement their number with battery operated models, since fires can cause electrical failures and during power outages, the detectors become non- functioning.

Spacing is important as well. To fully protect a home, detectors should be spread through the home not concentrated in one area, and also installed according to manufacturer’s recommendations on walls or ceilings; usually no closer than four inches from the ceiling and no lower than 12 inches from it for wall mounted units.

For more information in all areas of fire protection you can visit the website for Nation Fire Protection Association