Brick veneer vs double brick in Adelaide: NCC 2022

What does brick veneer mean, and what is double brick in NCC terms?

The Housing Provisions glossary defines a cavity as “a void between 2 leaves of masonry, or in masonry veneer construction, a void between a leaf of masonry and the supporting frame.” Clause 5.7.2(1) describes the veneer cavity as the one “between the masonry veneer and the exterior face of the supporting frame”. In a brick veneer wall, the masonry is the outer skin and the frame — timber or steel, designed under H1D6 — is the structure it is tied to.

The NCC text does not use the words “double brick”. Clause 5.1.1(1) lists masonry veneer (Part 5.2) and cavity masonry (Part 5.3) as separate Deemed-to-Satisfy Provisions, and Volume Two H1D5(2) refers to “cavity brick unreinforced masonry”. Clause 5.3.3(2) states: “Cavity masonry walls must be constructed of two leaves, with each leaf not less than 90 mm wide.”

Section 5 also covers single leaf unreinforced masonry (Part 5.4), isolated masonry piers (Part 5.5), masonry components and accessories (Part 5.6) and weatherproofing of masonry (Part 5.7). Reinforced masonry is outside it: clause 5.1.1(2) refers to H1D5(4) for that.

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When can each wall be built to the Housing Provisions?

Volume Two clause H1D5(1) treats the structural Performance Requirement H1P1 as satisfied for masonry veneer designed and constructed in accordance with AS 3700, or AS 4773.1 and AS 4773.2, or Part 5.2 of the Housing Provisions provided: the building is in an area with a wind class of not more than N3; the veneer walls are built on footings or slabs complying with H1D4 and comply with Part 5.6 using components that comply with Part 5.7; “the building site soil classification is A, S or M in accordance with AS 2870”; “the framing that the masonry wall is tied to complies with H1D6”; the building is not in an alpine area; and Appendix A of AS 1170.4 contains no specific earthquake design requirements for it.

H1D5(2) sets the same structure for cavity brick unreinforced masonry, with Part 5.3 as the Housing Provisions route, provided “the building is located in an area with a design wind speed of not more than N3”, and the same other conditions, less the one about framing. Outside those conditions, AS 3700 and AS 4773 remain the listed Deemed-to-Satisfy routes, and a Performance Solution is another route under H1D1. This note does not describe the content of those Standards.

South Australia’s variations to Volume Two Part H1 list only SA H1P2 (buildings in flood areas), which that page shows as deliberately left blank. The site classification and the footing design are covered in separate notes.

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What do Parts 5.2 and 5.3 require of each wall?

Both Parts limit height in the same words: masonry veneer walls (5.2.2) and cavity masonry walls (5.3.2) “must not be greater than 8.5 m in height when measured above the adjacent finished ground level.” Both require openings to be spanned by steel lintels, except openings “not more than 500 mm wide” that are adequately supported (5.2.3, 5.3.5). Both send damp-proof courses and flashings to 5.7.3 and 5.7.4, and vertical articulation joints to 5.6.8.

Clause 5.3.3(1) requires the height of the wall between lateral supports — floor, ceiling or roof diaphragm — to be “not more than 3 m”, and walls subject to wind loads to be supported by masonry cross walls, which must be “not less than 2 m in length”, or by steel mullions. Clause 5.3.3(3) requires the cavity to be “not less than 35 mm and not more than 75 mm in width”, maintained between the outer leaf and any insulation or services in the cavity. Internal masonry walls must be “not less than 75 mm thick” under 5.3.4(1).

Flashings, damp-proof courses and weepholes: the national Part 5.7 text and SA’s change

In South Australia, SA H2D4(2) lists AS 3700 or AS 4773 Parts 1 and 2 as the Deemed-to-Satisfy routes for weatherproofing of masonry; Part 5.7 is not listed. Nationally, H2D4(2) lists AS 3700, AS 4773.1 and AS 4773.2, or Part 5.7; SA H2D4(2) deletes that subclause and inserts a version listing “AS 3700 - Masonry structures; or AS 4773 - Masonry for small buildings, Parts 1 and 2.” Part 5.7 is still referred to from Parts 5.2 and 5.3 (5.2.4, 5.3.3(1), 5.3.6) and from H1D5(1) and (2) for components. How the two fit for a particular wall is for the relevant authority assessing the building work to confirm.

SA H2D4(3) states that “metals and bitumen-coated metals referred to in clauses 7.2. and 7.3 of AS/NZS 2904 are not acceptable materials for use as damp-proof courses in South Australia”. SA H2D4(4) states that in low rainfall intensity areas where the site classification is A, S, M, M-D, H, H1, H2, H-D, H1-D or H2-D in accordance with AS 2870, the height of the damp-proof course may be “15 mm above finished paved, concreted or landscaped areas” or “0 mm if the damp-proof course is protected from the direct effects of the weather by a carport, verandah or the like.”

In the national Part 5.7 text, clause 5.7.2 sets the clear cavity width for masonry veneer at not less than 25 mm and not more than 75 mm, and for cavity masonry at not less than 35 mm and not more than 75 mm. On a slab-on-ground, “the cavity must be drained to the outside in accordance with 5.7.5”, and “the exterior masonry leaf must not overhang the edge of the slab by more than 15 mm.”

In the same national text, clause 5.7.4(1) requires damp-proof courses and flashings to form a continuous barrier in listed locations, including “around the bottom perimeter of walls where constructed on a concrete slab” and “to the bottom and tops of windows and doors and the like”. Under 5.7.4(2) a damp-proof course must be not less than 150 mm above the adjacent ground level, or 75 mm above paved, concreted or landscaped areas that slope away from the wall, and lower figures in listed cases; SA H2D4(4) sets its own low-rainfall-area heights for the site classifications it lists. Clause 5.7.5(1) requires weepholes in the course immediately above any flashing, “a minimum of 50 mm in height” and “at not more than 1.2 m centres”, with exceptions in 5.7.5(2).

Sarking requirements for brick veneer: wall wrap behind the bricks

Part 10.8 deals with membranes in external walls in clause 10.8.1. The glossary defines a pliable building membrane as “a water barrier as classified by AS 4200.1”. Where one is installed in an external wall, clause 10.8.1(1) requires it to comply with AS 4200.1, be installed to AS 4200.2 and sit on the exterior side of the primary insulation layer.

Clause 10.8.1(3) covers walls without one: “Except for single skin masonry or single skin concrete, where a pliable building membrane is not installed in an external wall, the primary water control layer must be separated from water sensitive materials by a drained cavity.” The glossary defines the water control layer as “a pliable building membrane or the exterior cladding when no pliable building membrane is present.” This note does not decide whether the single skin masonry exception covers a veneer leaf.

The explanatory information to 5.7.2 adds: “The 25 mm clear width of the cavity needs to be maintained regardless of any wall membranes, sheet bracing or services installed to the supporting frame.” Clause 10.8.1(2), on vapour permeance by climate zone, is covered in the note on condensation management. Whether a particular wall has a membrane, and which class, is set in its drawings and specification.

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Brick veneer next to a separating wall

In attached houses, clause 9.3.1(4) of the Housing Provisions deals with the junction between a masonry veneer external wall and the separating wall between dwellings. Any gap between them must be “not more than 50 mm” and packed “with a mineral fibre or other suitable fire-resisting material with the packing arranged to maintain any weatherproofing requirements of H2D4.”

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Which wall decisions do the drawings settle?

The limits above depend on facts the documentation records: the wind class and site classification, the footing design under H1D4, the frame design under H1D6 for veneer, the cavity widths, the location of damp-proof courses, flashings and weepholes, and whether a wall membrane is used. Where a wall falls outside Parts 5.2 or 5.3, H1D5 lists AS 3700 and AS 4773 as the other Deemed-to-Satisfy routes.

NCC 2025 was published on 1 May 2026, and the ABCB’s adoption page lists South Australia as “BCA: 1 May 2027” and “PCA: 1 May 2026”. Which edition applies to a particular application is for the relevant authority assessing it to confirm.

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