AS 4773:2015 masonry in small buildings: builder's guide

TL;DR

AS 4773 (Parts 1 and 2, both current at 2015 edition) is the practical masonry standard for Class 1 houses and Class 10a garages. It sits inside the geometric limits that cover the overwhelming majority of residential builds: eaves height no more than 6.0 m, overall roof height no more than 8.5 m, building width no more than 16 m. If your job is within those bounds, AS 4773 plus the ABCB Housing Provisions 2022 (Section 5, free at ncc.abcb.gov.au) is the DTS path under NCC 2022 H1D5 without needing a structural engineer to design to the heavier AS 3700. Where AS 4773 limits are exceeded (taller buildings, Class 2 apartments, complex reinforced masonry), the job steps up to AS 3700 and typically needs an engineer. The most common site failures on AS 4773 jobs are missing or filled articulation joints, cavity not kept clear of mortar droppings, and ties at the wrong duty for the wind class.

In plain English

AS 4773 was developed specifically for masonry in houses and similar small structures. It was last published in 2015 (both parts incorporating Amendment No. 1 from November 2016) and remains the current edition (verified 2026-05-08, Standards Australia AS 4773.1:2015 and AS 4773.2:2015).

The standard comes in two parts:

AS 4773.1:2015: Design. Covers masonry wall design, wall tie selection, articulation joint requirements, mortar specification, lintel sizing, and the geometric limits.
AS 4773.2:2015: Construction. Covers workmanship on site, material handling, laying practices, control joints, cavity management, and built-in components.

AS 4773 applies to clay brick, concrete masonry, and calcium silicate (sandlime) masonry units with a leaf thickness of 90 mm or greater. It does not cover autoclaved aerated concrete (AAC) blocks, which are addressed under AS 5416.

The companion standard AS 3700:2018 covers all masonry structures, including the complex and larger-scale work outside AS 4773’s limits. For most residential jobs, AS 4773 is simpler and sufficient.

What it requires

NCC 2022 reference point

NCC 2022 Volume Two Clause H1D5 states that masonry in Class 1 and Class 10 buildings must be designed and constructed in accordance with either:

AS 3700, or
AS 4773.1 and AS 4773.2

Both are DTS paths. The ABCB Housing Provisions Standard 2022, Section 5 (Masonry) provides the same DTS rules in an accessible format and is free at ncc.abcb.gov.au (verified 2026-05-08, NCC 2022 Volume Two H1D5).

The Housing Provisions’ wind and site constraints mean AS 4773 via that pathway applies only where wind class does not exceed N3 and the site is classified A, S, or M under AS 2870. If your site is class H, E, or P, or in a cyclonic area above N3, you need engineered design.

Geometric limits of AS 4773

AS 4773 applies where the building geometry stays within all of the following limits (verified 2026-05-08, AS 4773.1:2015 Clause 1.2.2):

Parameter	Maximum limit
Eaves height above ground	6.0 m
Highest roof point above ground (excluding chimneys)	8.5 m
Building width (including roofed verandas, excluding eaves)	16.0 m
Building length	5 times the width
Individual storey height (floor to ceiling at external wall)	3.0 m
Roof pitch	35 degrees
Eaves width	900 mm

If any of these limits is exceeded, the masonry design steps up to AS 3700 and an engineer of record is required.

Masonry types and wall height limits

The Housing Provisions set the following maximum wall heights for the DTS path (verified 2026-05-08, NCC Housing Provisions 5.2 and 5.3):

Masonry type	Maximum wall height above finished ground
Masonry veneer	8.5 m
Cavity masonry	8.5 m
Unreinforced single leaf external	3.0 m between lateral supports

For cavity masonry, the wall between lateral supports must not exceed 3.0 m in height. Cross walls providing lateral support must be at least 2.0 m long and spaced no more than 5.1 m apart. Each masonry leaf must be at least 90 mm thick. The cavity must be 35 mm to 75 mm clear width.

For masonry veneer, the cavity between the veneer leaf and the frame backing must be 25 mm to 75 mm clear width. Mortar droppings (snots) that fall into the cavity and bridge the gap are the most common cause of cavity failure.

Wall ties (Housing Provisions 5.6.5)

Wall ties must comply with AS 2699.1 and be selected to match the wind class and masonry type. The minimum duty ratings from the Housing Provisions (verified 2026-05-08, NCC Housing Provisions 5.6.5):

Masonry type	Wind class	Minimum tie duty
Masonry veneer	N2 or below	Light duty
Masonry veneer	Above N2	Medium duty
Cavity masonry	N1	Light duty
Cavity masonry	Above N1	Medium duty

Maximum tie spacing: 600 mm horizontally and vertically for cavity masonry. For veneer with 450 mm stud spacing, maximum 450 mm horizontal and 600 mm vertical. For veneer with 600 mm stud spacing, maximum 600 mm horizontal and 400 mm vertical.

Critical fixing positions: ties must be placed within 300 mm of panel edges and openings, within 300 mm or two courses (whichever is less) of the top and bottom of any veneer panel, and within the first two courses at DPC level. Ties must embed at least 50 mm into each masonry leaf.

Corrosion protection requirements increase with coastal exposure:

Location	Minimum protection
Within 1 km of breaking surf, within 100 m of salt water, or heavy industrial	Grade 316L stainless steel or engineered polymer
1 km to 10 km from breaking surf, 100 m to 1 km from salt water	470 g/m2 hot-dip galvanised post-manufacture, or Grade 304L stainless
All other areas	300 g/m2 galvanised coating

Articulation joints (Housing Provisions 5.6.8)

Articulation joints are vertical movement control joints built into masonry walls to accommodate thermal expansion, moisture change, and foundation movement. They must have a minimum width of 10 mm and be filled with flexible sealant backed by compressible foam or a purpose-made backer rod.

Spacing rules (verified 2026-05-08, NCC Housing Provisions 5.6.8):

Wall condition	Maximum joint spacing	Placement note
Straight wall, openings under 900 mm x 900 mm	6 m centres	Within 4.5 m of corners; not closer than 470 mm to a corner
Straight wall, openings 900 mm x 900 mm or over	5 m centres	Within 1.2 m of any opening
At wall height changes exceeding 20%	At the change point	Continuous through the full leaf height
At thickness changes, footing joints, or material junctions	At the change point	Continuous

Exception: articulation joints are not required on sites with soil classification A or S under AS 2870.

The joint must be continuous through the full height of the masonry leaf. Partial joints, mortar-filled joints, or joints that are bridged at any course level provide no movement capacity and will cause diagonal cracking. This is the defect most commonly missed on site.

Mortar mixes (Housing Provisions 5.6.3)

Mortar proportions by volume (cement:lime:sand) depend on exposure class (verified 2026-05-08, NCC Housing Provisions 5.6.3):

Exposure class	Clay/calcium silicate masonry (cement:lime:sand)	Concrete masonry (cement:lime:sand)
Protected (internal or coated external)	1:2:9	1:0:5
General purpose	1:1:6	1:0:5
Exposure (salt attack zones)	1:0.5:4.5	1:0:4.2

Nominal bed and perpend joint thickness is 10 mm. Raked joints are not allowed in saline or heavy pollution environments. Maximum raking depth is 5 mm for units 90 mm wide, and 10 mm for units 110 mm wide.

Masonry workmanship tolerances

The maximum permitted deviation for finished brickwork plumb and straightness in residential construction is pending verified member access to the HIA Guide to Materials and Workmanship. [HIA-060]

AS 4773.2:2015 itself includes workmanship tolerances for the construction phase (setting out, levelling, courses), but the post-completion acceptance tolerances for a builder’s practical inspection use the HIA Guide values. State Guides to Standards and Tolerances (e.g. Victoria’s Guide) are partially public; check your state regulator’s website for what is accessible before the HIA tracker is resolved.

What it doesn’t cover

AS 4773 does not apply to:

Class 2 buildings (apartments): must use AS 3700 with engineer design
Class 5 to Class 9 buildings (commercial): covered by NCC Volume One and AS 3700
Buildings outside the geometric limits in Clause 1.2.2: step up to AS 3700
Autoclaved aerated concrete (AAC) blocks: covered by AS 5416, not AS 4773
Earth masonry (rammed earth, mud brick): not covered; performance solution required
Masonry retaining walls not associated with a building: separate structural design

Practical implications

Choosing AS 4773 versus AS 3700 on a house

For a standard Class 1 house or townhouse sitting within the 6.0 m eaves height and 16.0 m width limits, AS 4773 is the right DTS path. The brickie and the builder use the Housing Provisions (Section 5) as the day-to-day working document; AS 4773 is the nominated standard backing those provisions.

AS 3700 applies when:

The building is Class 2 (apartments) or the engineer has been engaged for a specific reason
Any geometric limit in AS 4773 Clause 1.2.2 is exceeded
The masonry is complex (large reinforced piers, prestressed elements, unusual loads)
The certifier or structural engineer specifies AS 3700 by reference

On most suburban residential builds, the builder will never open AS 4773 directly. The Housing Provisions are the accessible document. AS 4773 is the backstop that Housing Provisions compliance relies on.

Sequencing on site

The critical construction sequence for masonry compliance on a house:

Footings and slab complete, DPC laid at base course level before the first brick goes down
First course laid to line, weep holes formed at DPC level (maximum 1.2 m centres)
Cavity kept clear of mortar droppings throughout, especially in the lower courses where snots accumulate fastest
Wall ties placed at correct centres and duty as the inner frame rises; critical positions at DPC, at openings, and at panel edges
Articulation joints formed at designed locations, continuous through the full leaf height, backed with compressible foam
Flashings and DPC installed above openings and at roof abutments before masonry continues
Weep holes formed immediately above each flashing course
Mortar mix matched to exposure class; raked joints avoided in coastal locations

Common defects under AS 4773

These failures show up repeatedly in building inspections and warranty claims:

Defect	Cause	Impact
Articulation joints filled or missing	Not formed, or later filled with mortar snots	Diagonal cracking as thermal movement accumulates
Articulation joints not continuous	Stopped partway up the wall height	Partial movement only; cracking resumes above the stopped point
Cavity bridged by mortar droppings	Not cleaned during construction	Moisture path across cavity; rising damp; tie corrosion
Cavity width outside 25 mm to 75 mm range	Inconsistent frame or brick setting out	Ties overstressed (too wide) or mortar bridging (too narrow)
Ties wrong duty for wind class	Light duty in exposed coastal or high-wind locations	Veneer detachment risk in high-wind events
DPC below 150 mm above ground	Set too low, or ground built up after construction	Rising damp pathway into wall cavity
Weep holes blocked or missing	Snots at base course; not formed above lintels	Moisture ponds in cavity; potential corrosion of lintels and ties
Wrong mortar mix for exposure class	Protected mix used in coastal/saline locations	Accelerated mortar degradation; joint failure

Source link

Standards Australia store: AS 4773.1:2015 and AS 4773.2:2015 (verified 2026-05-08). Both parts are paywalled. The free working document is the ABCB Housing Provisions 2022, Section 5 Masonry.

References

Standards Australia, AS 4773.1:2015 (incorporating Amendment No. 1) Masonry in small buildings, Part 1: Design. https://store.standards.org.au/product/as-4773-1-2015 (verified 2026-05-08).
Standards Australia, AS 4773.2:2015 (incorporating Amendment No. 1) Masonry in small buildings, Part 2: Construction. https://store.standards.org.au/product/as-4773-2-2015 (verified 2026-05-08).
Australian Building Codes Board, NCC 2022 Volume Two, Part H1 Structure, Clause H1D5 Masonry. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two/h-class-1-and-10-buildings/part-h1-structure (verified 2026-05-08).
Australian Building Codes Board, ABCB Housing Provisions Standard 2022, Section 5 Masonry. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/housing-provisions/5-masonry (verified 2026-05-08).
Australian Building Codes Board, ABCB Housing Provisions Standard 2022, Part 5.6 Masonry components and accessories. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/housing-provisions/5-masonry/part-56-masonry-components-and-accessories (verified 2026-05-08).

AS 3700:2018 masonry structures, the parent standard that AS 4773 sits within and steps up to for complex or larger buildings
NCC 2022 Volume Two, the residential building code that calls up AS 4773 under H1D5 Structure
Brickie (trade), what a bricklayer covers, licensing, tolerances, and what to require in their quote
NCC structure, BCA and PCA, how the structural performance requirements sit within the NCC framework
Articulation joint, the vertical movement control joint required by Housing Provisions 5.6.8
Cavity masonry, double-leaf masonry with a clear cavity between leaves
Masonry veneer, single masonry leaf tied to a structural backing frame