Australian Standard Contracts
Australian Standard Contracts
AS 4000, AS 2124, AS 4300 and AS 4902 are the standard form contracts that carry most commercial and civil construction in Australia. Advice, review, drafting and negotiation from a solicitor who is also a registered architect.
The Australian Standard (AS) suite is a family of standard form contracts published by Standards Australia and prepared by industry drafting committees. They set out the general conditions that govern the relationship between a principal and a contractor: how the work is administered, how progress payments and variations are handled, how extensions of time and delay costs are claimed, and how disputes are resolved. They are the most widely used standard forms on commercial, civil and infrastructure projects across the country.
The suite divides along the line that matters most on any project: who is responsible for the design. AS 4000 and AS 2124 are construct-only contracts, used where the principal supplies the design and the contractor builds to it. AS 4300 and AS 4902 are design and construct contracts, used where the contractor takes on the design as well as the construction. Each is administered by a Superintendent, and each is almost always amended by special conditions before it is signed.
Christopher Larcos advises principals, contractors, consultants and subcontractors on these contracts across Australia. Because he is a dual-qualified solicitor and registered architect with more than 40 years in the construction industry, he reads a standard form the way it is actually used on site, not only the way it reads on the page. That grounding is particularly valuable because these contracts are administered by a Superintendent, a role he understands from having performed it.
The contracts we advise on
AS 4000-1997
AS 4000-1997 is the most widely used construct-only head contract in Australia. Advice, review, special conditions and disputes, from a solicitor who is also a registered architect.
AS 4000 adviceAS 4000:2025
AS 4000:2025 is the modernised edition of Australia most widely used construct-only contract. Advice on what changed from AS 4000-1997, and which edition suits your project.
AS 4000:2025 adviceAS 2124-1992
AS 2124-1992 is the long-standing construct-only contract still used across civil, engineering and building work. Advice, review, special conditions and disputes, from a solicitor and registered architect.
AS 2124 adviceAS 4300-1995
AS 4300-1995 is the design and construct form of the earlier Australian Standard suite. Advice on design risk, novation, special conditions and disputes, from a solicitor and registered architect.
AS 4300 adviceAS 4902-2000
AS 4902-2000 is the most widely used design and construct contract in Australia. Advice on design risk, novation, special conditions and its AS 4903 subcontract, from a solicitor and registered architect.
AS 4902 adviceConstruct only or design and construct?
Construct only (AS 4000, AS 2124)
- The principal supplies the design; the contractor builds to it.
- Design risk stays largely with the principal and its consultants.
- AS 4000 (1997, with a modernised 2025 edition); AS 2124-1992 remains in wide use.
- Administered by a Superintendent who certifies payments and decides claims.
Design and construct (AS 4300, AS 4902)
- The contractor takes on the design as well as the construction.
- Design risk shifts to the contractor, often reinforced by special conditions.
- AS 4902-2000 is the modern form; AS 4300-1995 is its predecessor.
- Supports design and construct, design development and construct, and novation.
Choosing the right form, and amending it well, decides how risk is shared. The wrong form, or an unbalanced set of special conditions, is where most contract disputes begin.
What advice on a standard form contract covers
Choosing the right form
Advice on whether a construct-only or design and construct form suits the project, and which contract in the suite fits the procurement method, the design responsibility, and the risk you are willing to hold.
Drafting and reviewing special conditions
These contracts are rarely signed unamended. The special conditions are where risk is really allocated, and where a poorly drafted amendment can undo the balance of the standard form. This is drafting and review by someone who has administered the contract itself.
Risk allocation and design responsibility
Advice on where design risk, latent conditions, time risk and cost risk sit under the form and any amendments, and whether that allocation is workable and insurable for the party you act for.
The Superintendent and administration
Advice on the Superintendent role, certification, assessment of progress claims, and the decisions on variations and extensions of time that most often become disputes.
Security of payment interaction
How the contract payment regime works alongside security of payment legislation in the relevant state or territory, so payment claims, schedules and timing are handled correctly.
Disputes and adjudication
Strategic advice when a claim, a certification or a delay becomes contentious, informed by direct experience as an adjudicator under security of payment legislation in five jurisdictions.
Common questions
What are the main Australian Standard construction contracts?
The most widely used are AS 4000 and AS 2124-1992 for construct-only work (where the principal supplies the design), and AS 4300-1995 and AS 4902-2000 for design and construct work (where the contractor takes on the design). AS 4000 exists in the original 1997 edition and a modernised AS 4000:2025 edition; together with AS 4902 it forms the modern AS 4000 suite, while AS 2124 and AS 4300 are the earlier suite and remain in wide use. Each also has a companion subcontract form.
Which Australian Standard contract should I use?
It depends on who is responsible for the design and how the project is procured. If the principal supplies the design, a construct-only form such as AS 4000 or AS 2124 is usual. If the contractor is to design and build, a design and construct form such as AS 4902 or AS 4300 is used. The right choice, and the special conditions attached to it, should reflect the risk each party can realistically manage and insure.
Do these contracts need special conditions?
Almost always. The standard forms are a balanced starting point, but they are rarely signed unamended. Special conditions adjust risk allocation, payment, time, insurance and dispute resolution to the specific project. The quality of those amendments matters as much as the choice of form, because a poorly drafted special condition can undo the balance the standard form was designed to strike.
Can you advise both principals and contractors?
Christopher advises principals, contractors, consultants and subcontractors on these contracts, though on any single matter he acts for one party. The value of a dual-qualified adviser is the same on either side: advice grounded in how the contract is administered and how the work is actually built, not only in how the clauses read.
Why Christopher
- Dual-qualified solicitor and registered architect
- Fellow of the Australian Institute of Architects (FRAIA)
- 40+ years in the construction industry
- Adjudicator across five Australian jurisdictions