How many smoke alarms should I have in my home?

The Ontario Fire Code requires a smoke alarm that meets CAN/ULC-S531 between each sleeping area and the remainder of the building. The Office of the Fire Marshal recommends that homeowners install one smoke alarm on every level of their home and outside all sleeping areas. For maximum protection, we suggest installing a smoke alarm in every room.

How often should I change the batteries in my smoke alarm?

Smoke alarm batteries are to be changed as per the manufacturer’s recommendations. We suggest changing 9-volt alkaline batteries every six months. Lithium batteries are supposed to have a 10-year life span. Both should be tested (monthly). If there is a malfunction, replace the battery and/or the alarm immediately.

I can't afford a smoke alarm, can the fire department help?

Windsor Fire & Rescue Services will install a smoke alarm, free of charge for a resident homeowner who cannot afford them. Landlords are responsible to provide smoke alarms and batteries for smoke alarms in their rental properties.

Is it permissible to replace existing permanently hardwired individual smoke alarms or electrically interconnected smoke alarms with battery powered smoke alarms?

No. When smoke alarms are being replaced, the installation must not reduce the level of detection required by the Building Code in effect at the time of construction of the dwelling unit, or by municipal by-laws in effect before the Fire Code adopted this requirement. This requirement is contained in Sentence of the Fire Code. In other words, existing permanently wired individual smoke alarms or electrically interconnected smoke alarm installations must be maintained to provide the same level of protection as originally required. Any replacement smoke alarms must be of a type comparable to the original (or better).

When a storey includes two levels, where is the best place to install the smoke alarm?

It is best to install the smoke alarm in the higher ceiling area, as the smoke alarm will react quickest to smoke development in either area in this arrangement. As well, smoke alarms are best installed near the stairs that interconnect the levels or storeys. Always install the smoke alarms on the ceiling or on the upper portion of a wall in accordance with the manufacturer’s instructions.

Where are smoke alarms required to be located in each dwelling unit?

A smoke alarm is required to be installed between each sleeping area and the remainder of the dwelling unit. Where the sleeping areas are served by hallways, the smoke alarms must be installed in the hallways.

In addition, at least one smoke alarm is required to be installed on each storey that does not contain a sleeping area.

Which type of smoke alarm should I purchase?

Individuals should assess the circumstances of their household and select the most appropriate alarm, however an important consideration in the purchase of a smoke alarm is conformance to a recognized standard. In Ontario, CAN/ULC-S531 is the recognized standard for both the ionization and photoelectric types of alarms. Both ionization and photoelectric type products conforming to this standard are available on the market. A homeowner will know that a smoke alarm meets the requirements of this standard by the ULC or cUL label on the device.

Who is responsible for installing and testing smoke alarms in my apartment? The tenant or the landlord?

It is the legal responsibility of the owner to install and maintain smoke alarms, unless stated in the lease agreement that the tenant is responsible. Condominium owners consult with the Condominium Board to determine who is the owner and who is responsible for smoke alarms in the suites.

If additional smoke alarms are being installed to comply with the Fire Code, do they have to be electrically interconnected to the existing smoke alarms?

No. Battery operated smoke alarms are acceptable as additional units in areas that were not protected by hard wired or hard wired interconnected. If a hard wired smoke alarm requires replacement then it must be replaced with a hard wired unit.

Where a dwelling unit is of a split-level design, is a smoke alarm required on each separate level?

No. A smoke alarm is not required on each level in a split-level dwelling unit because each level does not count as a separate “storey”.

To determine the number of storeys in a dwelling unit, and thus determine the number of smoke alarms required, it is necessary to first identify the “first storey” of the dwelling unit.

The Fire Code defines the “first storey” as meaning the storey with its floor closest to grade and having its ceiling more than 1.8 m above grade.

Once the first storey has been identified, it is then possible to identify the basement. The Fire Code defines a basement as meaning a storey or storeys of a building located below the first storey. Similarly, once the first storey is identified, it is then possible to identify the second storey and, where applicable, the third storey. As illustrated below, a storey can consist of more than one level. Only one smoke alarm is required to be installed in each storey (see note 1). However, when a dwelling unit contains multiple sleeping areas, a smoke alarm must be installed to protect each separate sleeping area. This may necessitate additional smoke alarms on some levels of a split-level home (see note 2). The following illustrated example of a split-level dwelling unit is provided for clarification.

split level home

Note 1: One smoke alarm required for each of the basement, first and second storeys.

Note 2: An additional smoke alarm is required on the lower level of the second floor due to sleeping rooms.

Which type of smoke alarm do you recommend?

There are two types of alarms – ionization and photoelectric. They operate on different principles and therefore may respond differently to various conditions. Some advantages to each type are set out below:


  • Fastest type to respond to flaming fires
  • Lowest cost and most commonly sold
  • Some models have a hush or temporary silence feature that allows silencing without removing the battery
  • Some models are available with a long life battery


  • Fastest type to respond to slow smouldering fires and white or grey smoke
  • Less prone to nuisance alarms from cooking

Photoelectric smoke alarms may respond slightly faster to smouldering fires, while ionization alarms respond slightly faster to flaming fires. Since you can’t predict the type of fire that will occur, it is difficult to recommend which is best. Both alarms will detect all types of fires that commonly occur in the home. Installing both types of smoke alarms in your home can enhance fire safety.