Fire rated walls on the boundary in SA: NCC 2022

When does a wall near the boundary need to be fire rated?

South Australia deletes clause 9.2.1 of the Housing Provisions and inserts SA 9.2.1, which provides that an external wall of a Class 1 building, “and any openings in that wall”, must comply with 9.2.3 if the wall is less than “900 mm from an allotment boundary other than the boundary adjoining a road alignment or other public space”, “1.8 m from another building on the same allotment other than an appurtenant Class 10 building associated with the Class 1 building or a detached part of the same Class 1 building”, or “3 m from a brush fence”. The brush fence trigger is the South Australian addition; the Housing Provisions define a brush fence as one “primarily constructed of Broombrush”.

Behind it sits Performance Requirement H3P1 of Volume Two, which South Australia also replaces. SA H3P1(1) requires a Class 1 building to be protected from the spread of fire from another building other than an associated Class 10 building, from the allotment boundary other than a boundary adjoining a road or public space, and from a Class 10b brush fence. Clause H3D3 provides that compliance with Part 9.2 satisfies H3P1 for fire separation of external walls. Part 9.2 is a Deemed-to-Satisfy provision, and a Performance Solution is the other route the Code allows.

The ABCB records that NCC 2025 was published on 1 May 2026, and lists South Australia as “BCA: 1 May 2027” and “PCA: 1 May 2026”, noting that some requirements may apply at different times or not at all because of state or territory variations. The edition that applies to a given application is for the relevant authority assessing the building work to confirm.

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Boundary wall fire rating requirements: how the wall is built

Clause 9.2.3(1) requires an external wall, including a gable, that must be fire-resisting to commence at the footings or ground slab, except where it commences above a separating wall complying with 9.3.1. It must extend to the underside of a non-combustible roof covering — it may stop “not more than 200 mm from the underside of a non-combustible roof covering, where the area between the external wall and underside of the roof covering is sealed with a non-combustible fascia, gutter or flashing” — or to the underside of a non-combustible eaves lining.

Clause 9.2.3(2) gives three forms of construction. The wall must “have an FRL of not less than 60/60/60 when tested from the outside; or be of masonry-veneer construction in which the external masonry veneer is not less than 90 mm thick; or be of masonry construction not less than 90 mm thick.” The Housing Provisions define a fire-resistance level as grading periods in minutes for structural adequacy, integrity and insulation, “expressed in that order”.

The explanatory information to the clause states: “A Performance Solution must be used where an external wall required to be fire-resisting does not commence in accordance with 9.2.3(1)(a).”

How the distance is measured, and how much of the wall is caught

Clause 9.2.2(1) measures the distance from any point on an external wall to an allotment boundary or another building “along a line at right angles from the allotment boundary or external wall of the other building”. Under clause 9.2.2(2), where a wall within a specified distance must comply with 9.2.3, “only that part of the wall (including any openings) within the specified distance need be constructed in that manner”. The note to Figure 9.2.2a states: “No protection required for the wall at right angles or more to the boundary.”

Clause 9.2.2(3) sets how the distance is taken between buildings of different heights. South Australia inserts SA 9.2.2(4): the distance from an external wall to a brush fence “is measured in any direction from the external wall.”

Windows and openings in a fire-rated external wall

Clause 9.2.3(3) requires openings in an external wall that must be fire-resisting to be protected by “non-openable fire windows or other construction with an FRL of not less than –/60/–; or self-closing solid core doors not less than 35 mm thick.”

Clause 9.2.3(4) makes an exception for a window in a non-habitable room that is not less than 600 mm from the boundary of an adjoining allotment, or 1.2 m from another building on the same allotment: in a bathroom, laundry or toilet the opening may be up to 1.2 m2; in other rooms up to 0.54 m2, where the window is steel-framed with no opening sashes and glazed in wired glass, or the opening is enclosed with translucent hollow glass blocks. Under clause 9.2.3(5), subfloor vents, roof vents, weepholes, control and construction joints and penetrations for pipes and conduits need not comply with subclause (3).

Eaves, gutters and other encroachments in SA

South Australia replaces clause 9.2.9 with SA 9.2.9. Within 900 mm of an allotment boundary, within 1.8 m of another building on the same allotment or within 3 m of a brush fence, SA 9.2.9(3) allows non-combustible fascias, gutters and downpipes; light fittings, electricity or gas meters, aerials or antennas; pergolas, sun blinds or water tanks; and “unroofed terraces, landings, steps and ramps, not more than 1 m in height.”

SA 9.2.9(4) allows combustible fascias, gutters and downpipes, eaves with non-combustible roof cladding and lining, and flues, chimneys, pipes, domestic fuel tanks, cooling or heating appliances and other services “up to but not closer than 450 mm from an allotment boundary” or 900 mm from another building on the same allotment. SA 9.2.9(5) lets eaves with non-combustible cladding and soffit encroach within 450 mm at the corner of the roof, where the walls are at least 900 mm from the boundary and set at between 20 and 70 degrees to it. SA 9.2.9(6) keeps the fascias in (4)(a) at least 3 m from a brush fence.

Clause 9.2.10 limits combustible roof lights and skylights in a roof required to have a non-combustible covering to an aggregate of not more than 20% of the roof, and not less than 900 mm from “the allotment boundary other than the boundary adjoining a road alignment or other public space”. How SA 9.2.9 applies to a particular deck is for the relevant authority to confirm; the note on attached decks covers how decks are fixed to a house.

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Garages and carports near the boundary

Clause 9.2.4(1) deals with a Class 10a building, such as a garage, between a house and a boundary or another building, and sends each arrangement to a set of acceptable methods in 9.2.5, 9.2.6 or 9.2.7. Where the Class 10a building is between the house and “a boundary alignment that is not a boundary with a road alignment or other public space”, clause 9.2.5 lists methods built from two options: keeping the buildings 900 mm from the boundary or from each other, or building the relevant external wall to clause 9.2.3.

South Australia inserts SA 9.2.4(3): “A carport or verandah may have timber posts and timber roof support beams regardless of their distance from the boundary.” It also replaces clause 9.2.8 with SA 9.2.8, under which a Class 10a carport is exempt from 9.2.4(1) if, among other conditions, it has two or more sides open and not less than one third of its perimeter open (or the alternative fire-resisting arrangement the clause describes), it has a polycarbonate or non-combustible roof covering, and it does not provide direct vertical support to any part of the house.

Walls between attached dwellings: separating walls

Where dwellings are attached, the wall between them is a separating wall, which the Housing Provisions define as “A wall that is common to adjoining Class 1 buildings” and note “may also be known as a party wall”. Clause 9.3.1(1) requires it to have an FRL of not less than 60/60/60 or be of masonry not less than 90 mm thick, to commence at the footings or ground slab, “except for horizontal projections to which 9.3.4 applies”, and to extend to the underside of a non-combustible roof covering, or to not less than 450 mm above a combustible roof covering.

A separating wall of lightweight construction must be tested in accordance with Specification 6 (clause 9.3.1(2)). Clause 9.3.1(3) provides that a separating wall complying with 9.3.1(1)(c)(i) — the one extended to the underside of a non-combustible roof covering — “must not be crossed by timber or other combustible building elements except for roof battens with dimensions of 75 x 50 mm or less, or roof sarking”, with any gap at the top packed with mineral fibre or other suitable fire-resisting material. Where there is a masonry veneer external wall, the gap between it and the separating wall must be not more than 50 mm and packed. Clause 9.3.2 sets the rules for service openings, electrical cables and outlets in the wall.

The Planning, Development and Infrastructure Act 2016 deals separately with neighbours’ rights over party walls; the note on party walls quotes it.

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The South Australian 600 mm Deemed-to-Satisfy provision for space between buildings

South Australia inserts SA H5P3 and SA H5D4 into Part H5 of Volume Two. SA H5P3 requires the space between buildings to be “sufficient to allow access for inspection and maintenance” to avoid an accumulation of rubbish that could bridge termite barriers, harbour vermin or create a fire hazard.

The Deemed-to-Satisfy provision is SA H5D4(2): unless the space between external columns is not infilled, “every part of an external wall of a building must be not less than 600 mm from— any boundary of the allotment, unless that wall is on or abutting that boundary; or the external wall of any other building on the same allotment, unless the two buildings are abutting.” How that provision and Part 9.2 apply together to a particular wall on a new build is for the relevant authority assessing the building work to confirm.

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