Ontario Building Code:

New construction and major renovations require the smoke alarms be brought up to current code:

  • Each sleeping area is to now have a smoke alarm with battery back up and flashing strobe.
  • All alarms are to be interconnected, one alarms sounds, they all sound.

• More than 90% of residential fires in Ontario are considered to have been preventable.
• 1 out of 17 preventable home fires results in a reported injury, and not all injuries are reported.
• Fatality occurs in 1 out of every 100 preventable home fires.

Research conducted between 1995 and 2004 concluded the following facts regarding smoke alarm usage in preventable residential fires causing detah in Ontario:
• In 35% of the cases - a smoke alarm was present and did operate
• In 25% of the cases - a smoke alarm was present but did not operate
• In 21% of the cases - no smoke alarm was present
• In 19% of the cases - a smoke alarm was present but its operational status could not be determined

These figures pertain to 609 residential fire related fatalities in Ontario during the period of this study. In nearly half of these fatal home fires there was no early warning from a smoke alarm. In the majority of these cases, it was determined that a dead battery, or a smoke alarm with no battery, was the reason for the alarm failing to activate.

Statistics also reveal that the holiday season between the beginning of November and the end of January is the greatest period in which residential fire fatalities occur. This highlights the need to be extra vigilant during this holiday period; ensuring that smoke alarms have fresh batteries installed at the beginning of the winter holidays could help reduce the risks involved should tragedy strike.

Are There Different Types of Smoke Alarms?
There are two types of technologies, ionization and photoelectric, used in the production of smoke alarms. These devices are designed to sound an alarm when the detection of smoke or other products of combustion occurs. Each type of alarm has its advantages and disadvantages and available products may use one or both technologies in a single unit.

Both types of alarms will alert you to a fire and may save lives when properly installed and maintained. It is a wise practise to purchase the highest quality alarm that your budget will allow - do not select a detector solely based on its low cost.

Smoke alarms may be battery operated or hard-wired into your home's electrical system. When replacing old or worn smoke alarms, it is important that the correct type of alarm be chosen as a replacement; hard-wired (or direct-wired) alarms cannot be replaced with battery-powered units.

Ionization Smoke Alarms
Ionization smoke alarms work by using a small amount of radioactive material (americium 241) that ionizes the air between two electrically charged plates. When smoke enters the chamber, the current of the elctrical flow is changed; the alarm is activated when this change is detected.  This type of alarm will activate more quickly for fast, flaming fires where there may be little visible smoke.

Qualities of Ionization Smoke Alarms

  • Cheaper than other types of smoke alarms
  • Very good with fast flaming fires with little visible smoke
  • Suitable for general use
  • Less prone to false alarms caused by dust and steam


  • Very susceptible to nuisance alarms due to cooking
  • May be slow to respond to slow smouldering fires
  • Contains radioactive material

Photoelectric (Optical) Smoke Alarms
In a sence, photoelectric smoke alarms "see" the smoke. The term photoelectric does not refer to the power source for the alarm as they may be either battery-powered or direct-wired. These alarms operate on the principle of scattered light reflecting off of the large air-borne particles that make up heavier, dense smoke. The scattered light then strikes a sensor which activates the alarm.

In normal conditions, there a a light source inside the alarm that emits a beam that shoots across to the other side without striking the sensor. It is only when smoke enters the chamber that this beam is disrupted and the light becomes scattered, thus striking the sensor which causes the alarm to sound.

Photoelectric smoke alarms are particulary more responsive to smoldering fires and the dense smoked produced by foam-filled furnishings.

Qualities of Photoelectric Smoke Alarms

  • Good for smouldering fires and dense smoke
  • Not as prone to cooking nuisance alarms
  • Contain no radioactive material
  • Suitable for general use


  • Prone to nuisance alarms from dust and insects – must be kept clean
  • More expensive
  • Contain no radioactive material

Ionization / Photoelectric Combination Smoke Alarms
Combination Ionization / Photoelectric alarms combine the two technologies to detect the presence of smoke or products of combustion. An alarm can be activated by either of the sensors within the unit. A combination Ionization / Photoelectric alarm gives you the benefits of both types of technologies.

Combination Smoke Alarm / Carbon Monoxide Alarm
Alarms that combine smoke and carbon monoxide detection capabilities are also available in a single unit. These units incorporate different sounding alarms, or in some cases voice alerting of “Fire / Fire” or “Warning Carbon Monoxide” when detecting the presence of smoke and/or carbon monoxide. If a combination smoke alarm / carbon monoxide alarm is used, it must be installed on the ceiling to ensure that it will detect smoke effectively.

Battery-Operated Smoke Alarms and Direct-Wired or Hard-Wired (A/C) Smoke Alarms
A 9v alkaline battery powers most battery-operated smoke alarms. Some manufacturers also offer battery-operated smoke alarms powered by a long-life lithium battery.

Direct-Wired alarms are powered by a permanent connection to the household electrical supply. Many of these models also offer a battery-powered backup feature to provide protection when the power goes out.  Ontario Building Code requires all housed built from 1986 and newer to have hard-wired interconnected alarms.  Those being replaced when the life of the unit is over (10 years) are to be replaced with battery back up built in.

Are There Smoke Alarms Made for Individuals with Impaired Hearing?
The Ontario Building Code and the Ontario Fire Code both require the installation of smoke alarms in all residential occupancies. By definition, a smoke alarm must sound an audible alarm to alert the home’s occupants. Unfortunately, an audible alarm may not alert an individual with a hearing impairment.  New Ontario Building Code requires a flashing strobe light in all new construction or major renovations.

There are numerous smoke alarms available that address the specialized needs of these individuals. Some devices utilize a bright flashing strobe light, as well as an audible alarm, to alert the residents in the event of a fire. Due to the electrical supply requirements to operate these strobe lights, they must be wired directly into the home’s electrical system. Some models have a 9v battery backup that will ensure that the audible alarm will activate in the event of a power failure, however the battery will not activate the strobe light.

Additional options also exist that allow the individual to connect their smoke alarms to an alerting system that may, for example, incorporate a flashing strobe light, vibrating pager and/or vibrating bed shaker to alert the resident to the emergency.

Smoke Alarms