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AS/NZS 4455: masonry units, pavers, flags, and segmental retaining wall units

AS/NZS 4455 is the AU/NZ standard for masonry units. Sets the 230x110x76 mm work size, exposure/general/protected durability grades, and dimensional tolerances.

By Chalkline. Last updated 29 May 2026. Verified 29 May 2026.

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AS/NZS 4455 is the Australian/New Zealand Standard for masonry units (bricks, blocks, pavers, flags, and segmental retaining wall units). It defines the dimensions, durability classifications, and tolerances that the materials in a masonry wall, paving area, or retaining wall must meet. Part 1 of the series, AS/NZS 4455.1:2008, is the part most builders touch: it covers the unit specification for bricks and concrete blocks (verified 2026-05-29, see bricks, clay and concrete).

Where it sits

AS/NZS 4455 specifies the product, not how it is built into a wall. The neighbouring standards in the masonry stack:

  • AS/NZS 4455.1 (this article): the unit (the brick, the block).
  • AS 3700: the design and construction of the masonry structure (walls, piers, lintels). Calls up units complying with AS/NZS 4455.
  • AS 4773: masonry in small buildings (Class 1, Class 10). Also calls up AS/NZS 4455 for the units.
  • AS 2699: the built-in components (wall ties, lintels, connectors).
  • NCC 2022 Housing Provisions Part 5 references these standards as the deemed-to-satisfy path for residential masonry.

So AS/NZS 4455 is the unit-specification layer that the other masonry standards stand on.

What it sets

The substance for a residential builder:

  • Standard residential brick work size: 230 x 110 x 76 mm (verified 2026-05-29 per the live bricks-clay-concrete article). Each course plus a 10 mm mortar joint stacks to 86 mm, so 1,000 mm of wall height is roughly 11-12 courses.
  • Durability classification (3 grades):
    • Protected: internal use only, sheltered from direct weather.
    • General Purpose: most external walls in standard exposure conditions.
    • Exposure: severe coastal, saline, freeze-thaw, or aggressive ground-contact conditions.
  • Dimensional tolerances: how much the actual unit can vary from the work size, both in length and in face flatness.

The grades and tolerances are what the AS 3700 designer assumed and what the certifier checks the delivered units against on a job. A “General Purpose” brick delivered to a coastal site that needed “Exposure” is a non-conformance even if the wall is built per the drawings.

Why it matters

For a builder, AS/NZS 4455 surfaces in three day-to-day decisions:

  • Specify the right durability grade for the site. Coastal jobs need Exposure grade; substituting General Purpose because it is cheaper or easier to source creates a future durability problem that traces back to the spec, not the install.
  • Check the delivery docket. The supplier’s docket should reference AS/NZS 4455.1 and the grade. Without it, the bricks are not demonstrably compliant.
  • Match the mortar to the grade. NCC 2022 HP Table 5.6.3 sets specific cement:lime:sand mortar ratios for each exposure level (e.g. 1:2:9 for Protected, 1:0.5:4.5 for Exposure, see bricks-clay-concrete). Right grade brick + wrong mortar is still a defect.

For a builder

  • Order to the standard: “Bricks per AS/NZS 4455.1, General Purpose, 230x110x76 mm work size” tells the supplier exactly what to send.
  • Keep the docket: the AS/NZS 4455 reference and grade on the delivery paperwork are the proof of compliance.
  • Match exposure to site: coastal and salt-spray zones need Exposure-grade units. See AS 2699 wall ties for the matching tie corrosion class.
  • Don’t mix grades on one wall: the lowest grade in the wall sets the wall’s effective grade.

References

See also

Last updated: 2026-05-29. Verified: 2026-05-29. Quarterly review for currency.

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