Smoke alarm requirements for a new SA house

Which edition of the Building Code

The ABCB records that NCC 2025 was published on 1 May 2026, and that South Australia adopts its Building Code of Australia volumes from 1 May 2027. This note quotes the NCC 2022 edition, in which the smoke alarm provisions for houses sit in Part 9.5 of the ABCB Housing Provisions.

The same ABCB page notes that some requirements may apply at different times, or not at all, because of state or territory variations. Which edition applies to a particular application is a matter for the relevant authority assessing it, not something this page can settle.

What clause 9.5.1 requires

Clause 9.5.1 of the Housing Provisions states that smoke alarms must be located in a Class 1a building in accordance with 9.5.2 and 9.5.4, and in a Class 1b building in accordance with 9.5.3 and 9.5.4. They must comply with AS 3786, except that in a Class 10a private garage, where the use of the area is likely to cause spurious signals, another alarm deemed suitable under AS 1670.1 may be installed, provided alarms complying with AS 3786 are installed elsewhere in the Class 1 building.

They must be powered from the consumer mains source where a consumer mains source is supplied to the building, and they must be interconnected where there is more than one alarm. The explanatory information to the clause records that interconnection applies only within a single dwelling.

The South Australian variations listed on the ABCB’s Housing Provisions index, read on 28 September 2026, are to Parts 4.2, 9.2, 10.2 and 13.1. Part 9.5 is not among them. In NCC 2022 Volume Two, clause H3D6 provides that compliance with Part 9.5 satisfies Performance Requirement H3P2; the South Australian schedule to Volume Two varies Part H3 at H3P1 (spread of fire) only, not at H3P2 or H3D6.

Where the alarms go, and how high

For a Class 1a building — a detached house is the familiar example — clause 9.5.2 requires smoke alarms to be located in “any storey containing bedrooms, every corridor or hallway associated with a bedroom, or if there is no corridor or hallway, in an area between the bedrooms and the remainder of the building”, and in “each other storey not containing bedrooms”.

Clause 9.5.4 fixes the installation position. An alarm on the ceiling must be a minimum of 300 mm from the corner junction of wall and ceiling, and, in a room with a sloping ceiling, between 500 mm and 1500 mm from the high point and apexes. Where ceiling mounting is not possible, the alarm may go on the wall, a minimum of 300 mm and a maximum of 500 mm off the ceiling.

The explanatory information gives the reason: trapped hot air in a dead air space — at the apex of a cathedral ceiling, in the corner where wall meets ceiling, between exposed joists — can prevent smoke from reaching an alarm.

Regulation 95: dwellings of any age, and a title transfer

Regulation 95 applies to Class 1 and 2 buildings under the Building Code “whenever constructed”. It defines the approved standard as Australian Standard 3786 (as in force from time to time) or a Ministerial building standard published for the purposes of the regulation.

Subregulation (3) provides that, subject to any other requirement in the Building Code, one or more smoke alarms complying with an approved standard must be installed in each dwelling in locations that will provide reasonable warning to occupants of bedrooms so that they may safely evacuate in the event of fire.

Subregulation (4) attaches to a transfer of title. Within 6 months from the day title is transferred, each dwelling must have alarms meeting subregulation (3) that are powered through a mains source of electricity (unless the building is not connected to one) or by 10 year life non-replaceable, non-removable permanently connected batteries. Subregulation (5) makes the owner guilty of an offence where alarms are not installed in accordance with the regulation, and subregulation (6) extends “transfer of title” to strata units, community lots and units in a building unit scheme.

Before a new house is lived in

Regulation 103H applies, by subregulation (1), to a Class 1a building for which a certificate of occupancy is not required under the Regulations. Subregulation (2) provides that a person must not occupy such a building that has not been fully completed in accordance with a development authorisation unless several conditions are met — among them, at paragraph (d), that all smoke alarms required under the Building Code have been installed and tested.

Which houses fall under regulation 103H, and which need a certificate of occupancy instead, depends on transitional arrangements tied to approval dates that are not reproduced here. The council decides that for a particular building.

• Certificate of occupancy for a new house in SA
• The statement of compliance at the end of an SA build
• New build services