What is a variation in a construction contract?
A variation is a change to the work you originally agreed to do. It can add work, take work out, or change how, where or when the work is done. Most Australian construction contracts, including standard forms like AS 4000, let the principal (usually through the Superintendent or contract administrator) direct variations, and give the contractor a right to be paid for them under the contract's valuation rules.
Typical variations include:
- ✓Added work: an extra room, more piles, additional services runs.
- ✓Omitted work: scope taken out of your contract, sometimes given to someone else.
- ✓A changed specification or design: a different material, finish, level or dimension.
- ✓Changed access, sequence or timing: being told to stage the work differently, or to work out of hours.
- ✓Changes that come from revised drawings or instructions issued after you priced the job.
A variation is different from work that was already inside your scope. A lot of disputes come down to exactly that line: you say it is extra, the other side says it was always included. That is why the scope documents matter as much as the variation clause.
Does a variation have to be in writing?
Often, yes. Standard forms like AS 4000 expect the Superintendent to direct a variation in writing, and the contractor generally isn't entitled to vary the work without a direction. Many amended contracts go further and say that work done without a written direction won't be paid for.
In real life, variations start as a conversation on site: “can you just move that”, “while you're here, add this”. If you do the work on a verbal instruction alone, you may be relying on arguments about the other side's conduct or fairness to get paid. Those arguments sometimes succeed, but they turn on the facts and the contract wording, they are slow and expensive, and they put your cash flow at risk. Plan on not needing them.
- Don't start on a verbal instruction alone. If you are told to do something extra, ask for it in writing. If that is not possible, confirm it yourself by email the same day: who asked, when, what, and that you are proceeding on that basis. A confirming email is not always enough under the contract, but it is far better than nothing.
What it looks like in practice: AS 4000
Under the 1997 edition of AS 4000, clause 36 deals with variations: the Superintendent can direct a variation, and its value is worked out under the contract's valuation rules. The contract also has its own notice and claim periods that can apply to a variation claim, and the Special Conditions often tighten them. A change that looks routine on site can carry a short, hard deadline buried in the amendments.
- The Special Conditions usually win. A requirement to price a variation before doing it, a short window to claim, or a clause saying unauthorised work is unpaid can all sit in the amendments, far from the variation clause itself. Read the two together.
How are variations valued?
The contract decides. Standard forms typically value a variation in order: first by agreement, then using any rates or prices already in the contract (such as a schedule of rates), and, failing that, by reasonable rates and prices. Omissions are valued the same way, so a deduction can be argued as hard as an addition.
Whichever method applies, the claim is only as good as its evidence. Keep:
- ✓Labour records and timesheets for the extra work, kept separate from base-scope work.
- ✓Plant and material records, invoices and delivery dockets.
- ✓Subcontractor quotes, and the source of any rates you relied on.
- ✓Marked-up drawings or photographs showing the before and after.
- ✓A record of who directed the work, and when.
A variation usually affects time, too
Extra work often pushes out the program. A variation direction does not automatically give you more time: under most contracts you need to claim an extension of time separately, within its own notice period. Claiming the money and missing the time, or the other way round, is a common and costly mistake. Our guide to construction time bars covers how those notices work.
Why variation claims fail
- The instruction was verbal and nobody confirmed it. When the other side says "we never asked for that", there is nothing to point to.
- The notice went out late, or to the wrong person. The contract names who must receive it, how, and by when.
- The extra work was never separated from the base work. If you cannot show which hours, materials and plant went on the change, valuation turns into a negotiation.
- The price came after the work. Some contracts require pricing first. Even when they do not, a number agreed in advance avoids the argument afterwards.
- Nobody tracked it. Variations spread across emails, site meetings and phone calls. Without one register, claims go in late or not at all.
A practical variation checklist
- ✓Know your scope. Keep the scope documents to hand so you can say, by clause and page, why something is extra.
- ✓Get the direction in writing, from someone with authority under the contract. If it was verbal, confirm it by email the same day.
- ✓Give notice straight away, using the contract's method: the named recipient, the address and the form it requires, quoting the clause.
- ✓Say what it affects: cost, time, or both, and state that you will claim for each.
- ✓Price it early, ideally before you start, and ask for the price to be accepted or for a direction to proceed.
- ✓Record the extra work separately from the base work from day one.
- ✓Log every variation in one register with its notice date, status and amount claimed, and review it weekly.
- ✓Claim it in your next payment claim and follow it up. An unclaimed variation is easy to forget and hard to recover later.
What a good variation notice includes
There is no universal template, because contracts differ, but a strong notice usually covers:
- ✓The contract and the clause you are relying on.
- ✓What was directed, by whom, when and how: verbally, by email, at a site meeting, or through a revised drawing.
- ✓Why it is a change to the scope, with reference to the scope documents.
- ✓The expected effect on cost and on time, even if you only have an estimate.
- ✓A request for written confirmation or direction, with a date to respond.
- ✓A reservation of your rights if the full cost or time impact is not yet known.
Variations and security of payment
Once a variation is done, it can form part of a payment claim. Security of Payment laws give you a fast route to be paid, but each state sets its own deadlines and rules, and whether something was a valid variation is exactly the kind of question that gets argued in adjudication. Strong notices and records made at the time are what decide those arguments. Our plain-English guide to Security of Payment explains the state-by-state rules.
Where software can help
Variations are a tracking and paperwork problem as much as a legal one: a notice date to catch, a clause to quote, a register to keep up. AIgile's Smart Contract Administrator keeps track of the deadlines in your contract and helps draft notices grounded in the contract's own clauses, which you review, edit and send. It does not replace advice on a contested claim.
Common questions
What is a variation in a construction contract?
A change to the agreed scope of work: added, omitted or altered work, directed or agreed under the contract, and valued under its rules.
Can a variation be verbal?
Some contracts allow it, but many require a written direction, and unauthorised work may not be payable. Even where a verbal direction is allowed, you will need to prove it, so confirm it in writing the same day.
How long do I have to claim a variation?
It depends on the contract. Look for notice periods in the variations clause, in any general claims clause and in the Special Conditions, and for payment claim deadlines in the Security of Payment law of your state. Many are short, so notify early.
Who pays for a variation?
The party that directed it, under the contract's terms. Each contract in a chain works on its own terms, so approval upstream does not automatically mean a subcontractor downstream is paid, and the reverse also applies. Check what each contract says.
What if the principal refuses to pay for a variation?
Keep your records, follow the contract's claim and dispute processes, and consider the Security of Payment route in your state. Get advice early, especially if a deadline may be close.
Is a variation the same as a latent condition or an extension of time?
No. A variation is a change to the work, a latent condition is an unexpected physical condition, and an extension of time is more time. They can come from the same event, but each usually has its own notice requirements, so treat them separately.
This article is general information, not legal advice. Contracts differ and amendments matter. Check your own contract and get advice from a qualified Australian lawyer before relying on it.