AS 3600: concrete structures
AS 3600 is the Australian Standard for reinforced and prestressed concrete structures: cover, grade, and detailing for suspended slabs, beams, columns, and walls.
Ask Chalkline about this →AS 3600 is the Australian Standard for the design and detailing of reinforced and prestressed concrete structures. The current edition is AS 3600:2018, Concrete structures (with Amendment No. 1; verified 2026-05-25). It is engineer-driven: the structural engineer designs to AS 3600, and the concretor builds to the engineer’s details. It is called up by the NCC for structural concrete.
On a residential job it governs the engineered concrete elements, suspended slabs, beams, columns, basement and retaining walls, and anything outside the scope of AS 2870.
AS 3600 vs AS 2870 (the one that matters)
These two get confused constantly:
- AS 2870 Residential slabs and footings: the deemed-to-comply standard for on-ground slabs and footings for houses, sized off the site classification (M, H1, etc.). This covers the bulk of normal residential slab and footing work.
- AS 3600 Concrete structures: the general engineered-concrete standard for everything off the ground or outside AS 2870’s scope, suspended floors, columns, beams, transfer slabs, and retaining or basement walls.
A standard slab-on-ground house runs on AS 2870. The moment an element is suspended, retaining, or specifically engineered, it is designed to AS 3600. AS 2870 itself leans on AS 3600 for the structural design of its members.
Durability: exposure classification and cover
AS 3600 sets minimum concrete grade and cover to reinforcement based on the exposure classification of each element. There are seven classes, in order of increasing severity:
| Class | Roughly |
|---|---|
| A1, A2 | Interior / protected |
| B1, B2 | External, above ground |
| C1, C2 | Aggressive / marine |
| U | Unusual, assessed case by case |
The principle: the harsher the exposure, the higher the minimum concrete strength and the greater the cover over the steel. Durability cover sits in Section 4 of the standard; fire-resistance cover sits in Section 5, and the governing requirement is whichever is greater. The exact cover in millimetres depends on the exposure class, the grade, and the member, so it comes off the engineer’s drawings, not a rule of thumb.
This is why concrete cover and concrete grade on a pre-pour check are not arbitrary: they are AS 3600 durability and fire requirements.
Not the other AS numbers
The concrete and related-trade standards are easy to cross up:
- AS 3600: concrete structures (this one).
- AS 1379: specification and supply of the concrete.
- AS 3500: plumbing and drainage.
- AS 3660: termite management.
- AS 3700: masonry.
AS 3600 is the structural-design standard; AS 1379 is how the concrete that goes into it is ordered and supplied.
For a builder
- Build to the engineer’s details. On AS 3600 elements, cover, bar size, spacing, and grade are the engineer’s call. Do not eyeball cover or substitute grade.
- Cover is the common failure. Bars sitting too high (low cover) or chairs at the wrong height are the classic AS 3600 non-compliance, picked up at the pre-pour inspection. Cover is durability and fire protection, not a nicety.
- Match the concrete to the spec. The grade on the AS 1379 docket has to meet the AS 3600 minimum the engineer specified for that exposure.
- Know which standard applies. On-ground house slab and footings: AS 2870. Suspended slab, column, beam, or retaining wall: AS 3600 with an engineer.
Also known as: AS 3600-2018, AS 3600 concrete structures standard.
Related
See also
Last updated: 2026-05-25. Verified: 2026-05-25. Quarterly review for currency.