Smoke Alarm Requirements

Location – Class 1a buildings

1.    Smoke alarms should be installed on or near the ceiling in –

i)     between each part of the dwelling containing bedrooms and the remainder of the dwelling; and
ii)    where bedrooms are served by a hallway, in that hallway, and

(see figure, diagram a and figure



2.    Location of Smoke Alarms

When deciding on the position of smoke alarms it is important to remember that they are intended to detect smoke before it reaches to sleeping occupants of the building.

The ensuing alarm is designed to wake the occupants and give them time to evacuate the building.

3.    Explanatory Information

Sleep-outs or similar type residential buildings that are not connected to the remainder of the building by a hallway or other enclosed structure the alarm could be located in the room itself.

4.    Protection of Sleeping Areas in Buildings

Smoke alarms should be located “between each area containing bedrooms and the remainder of the dwelling”.

In some dwellings the bedrooms are located in a common area and connected by a hallway.  In this instance the alarm should be located as shown in figure, diagram a.

5.    Location of the Smoke Alarm on other Storeys

A smoke alarm is also required on each other storey that is not already provided with a smoke alarm.  It should be noted that smoke alarms are required to be installed in other storeys even if those other storeys consist of only car-parking, bathrooms, laundries and the like.  “Storey” in this context differs from the definition contained in BCA96 Volume One which excludes such spaces from being considered as storeys.

6.    Favoured Location

The favoured location for this alarm will in the path of travel people will most likely to take to evacuate the building.  The will ensure an alarm will be raised before smoke makes the common exit path impassible.

eg:  if the bedrooms are on the first floor, then an alarm should be positioned near the area of the inter connecting stair at ground level.

If the other storey is not connected to the remainder of the building (for instance a ground floor garage) then the alarm should be centrally located in the lower area.  However, it may be reasonable not to install smoke alarms where the storey is predominantly open, such as the basement level of a highest house on stumps that is used for car-parking or laundry purposes.

7.    Installation of Smoke Alarms

Smoke alarms should be installed on or near the ceiling with special care being taken to avoid dead air spaces.

A dead air space is an area in which trapped hot air will prevent smoke from reaching the alarm.  This space generally occurs at the apex of cathedral ceilings, the corner junction of walls and ceilings, between exposed floor joists etc (see diagram 1).

If it is impractical to mount smoke alarms on the ceiling then it may be located on the wall.  The recommended position is between 300mm and 500mm off the ceiling (see diagram 1).  The distance from the apex of a cathedral ceiling to the top of the alarm should be between 500mm and 1500mm.

8.     Nuisance Alarms

Smoke alarms are extremely sensitive and may detect smoke and moisture created by common household activities (such as burnt toast or steam from a bathroom).

Accordingly, to reduce the likelihood of nuisance alarms, the smoke alarm should not be located near cooking appliances and bathrooms.  However if it is necessary to locate alarms in these positions, an ionisation type alarm is more suitable near bathrooms, while a photoelectric alarm may be used near cooking appliances.