Here’s a story you’ve probably lived, or watched a mate live. The PM emails you on a Monday morning: “Can you strip out the extra section of blockwork by Wednesday? Owner’s directive.” Your crew hits it, gets it done, and you carry on with the job. Three weeks later, you drop it into your monthly claim as a variation. The head contractor comes back with two lines: “Refer clause 15.2 — notice not given within 5 Business Days. Claim rejected.”

The work happened. Your crew did it. The email is right there in your inbox. And the claim is dead — not because the work wasn’t real, but because a time bar clause killed it before you ever sat down to price it.

If you’re claiming up the chain on a commercial or civil project in Australia, this is the single most expensive mistake you can make. And it’s completely preventable if you understand what a time bar is, which clauses trigger it, and how to build a paper trail that survives it.

What a time bar clause actually does

A time bar (sometimes called a condition precedent in the legal reasoning) is a contract clause that says: if you don’t give written notice of a claim within a specific number of days, you lose the right to make the claim at all. Not “we’ll knock 10% off.” Not “we’ll dispute it.” Lose the right, permanently.

The reason head contractors and principals love them is simple — they force commercial certainty. If a variation, an extension of time, or a delay cost isn’t on the table within the notice window, the head contractor knows it never will be. It closes their exposure.

The reason subbies keep getting caught by them is also simple. The person who knows about the change — the supervisor on the tools — is not the person who writes the claim. By the time the paperwork lands on the office desk, the clock has already run. The claim gets in “when we do the next progress claim” instead of within the 5 or 10 Business Days the contract required.

The AS 4000 clauses that create the trap

The AS 4000-1997 general conditions of contract are the base document most Australian head contracts derive from. Here are the clauses that quietly control your variation and delay claims:

  1. 1Clause 36.1 — Direction to vary. If the Superintendent directs a variation, you must give written notice of your intention to claim payment before starting the varied work. Miss this and you may be treated as having done the work for free — even before any pricing dispute begins.
  2. 2Clause 36.4 — Pricing of variations. Priced claims must be submitted within a reasonable time. Most head contracts amend this to a fixed 10 or 14 Business Day window from the direction.
  3. 3Clause 34.3 — Extension of time claims. You must give notice of a qualifying cause of delay within 28 days of when you first became aware of it, and a detailed EOT claim within a further 28 days. Miss either and the EOT is barred.
  4. 4Clause 42.1 — Notification of claims. A catch-all for any claim not otherwise covered. Notice in writing to the Superintendent within 28 days of the event, with detailed particulars within a further period.
  5. 5Clause 20 — Latent conditions. Notice as soon as reasonably practicable, with detailed particulars promptly. “Reasonably practicable” gets read strictly — days, not weeks.

And that’s just AS 4000 in its standard form. Most head contractors amend those clauses to be tighter still. The 5 Business Days you keep hearing about isn’t standard — it’s an amendment you agreed to when you signed. Read your Special Conditions before every job. The variation notice window is the first place to look.

Reference guide: Turtons Legal — How to claim a variation under AS 4000 is a plain-English breakdown of these clauses written for subcontractors.

Australian courts enforce time bars — two cases you should know

Subbies sometimes assume that if the underlying claim is genuine, a court will find a way through the time bar. That’s not how Australian construction law works.

CMA Assets v John Holland [2015] WASC 217

Contract: subcontract for a WA infrastructure project. CMA Assets had legitimate extension of time claims worth hundreds of thousands of dollars. The issue was that CMA hadn’t given notice within the contractually specified window.

The Supreme Court of Western Australia held that where a contract clearly conditions the right to make an EOT claim on giving notice within a specific period, the courts will enforce that condition. Valid claims were disallowed solely because notice was late. No investigation of the merits, no discount for good faith — the claim was barred.

The takeaway: Australian courts treat time bars in construction contracts as conditions precedent, not procedural niceties. If the contract says notice within 5 Business Days is a condition of entitlement, that’s exactly what it means.

Valmont Interiors v Giorgio Armani [2021] NSWCA 93

Contract: fitout works for an Armani retail store in Sydney. The subcontract had a strict 5-Business-Day notice window for variation claims. Valmont routinely missed it; Armani’s project team routinely accepted the late notices anyway and paid the varied work.

When a disputed claim arose late in the project, Armani’s lawyers tried to invoke the time bar. The NSW Court of Appeal held that Armani’s conduct throughout the project — consistently accepting late notices, never objecting, paying for varied work — created a reasonable expectation that the time bar wouldn’t be strictly enforced. Armani was estopped from suddenly insisting on it.

Valmont won that argument, but it took a Court of Appeal decision to get there. As legal commentary from White & Case points out, estoppel is an expensive and unpredictable backstop. The reliable protection is compliance with the notice regime the first time.

The five traps that catch subbies most

These are the failure modes we see across almost every subcontractor commercial team we’ve talked to:

  1. Notice starts from the direction, not the paperwork. The clock begins when the head contractor tells you to do the work — verbal at the toolbox, email, RFI response, site instruction. Not when you get back to the office to type it up.
  2. “Business Days” excludes public holidays and often the site’s scheduled RDOs. Check the definition in your contract. A 5-Business-Day window over Easter could be 3 calendar days.
  3. An oral notice is almost never sufficient. “I told the site manager on Tuesday” will not save the claim. The notice has to be written, addressed to the person the contract names (usually the Superintendent), and delivered in the form the contract specifies.
  4. The notice of intention is separate from the priced claim. Most contracts require you to first say “I intend to claim,” then submit the priced claim later. Missing either can bar you.
  5. Latent conditions and directions to vary are two different regimes. A latent condition — unexpected rock, contaminated soil, undisclosed services — falls under clause 20, not clause 36. Different notice, different clock, different form.

The paper trail that beats a time bar

If you accept that time bars are enforceable, expensive, and routinely missed, the fix is a system that makes compliance automatic. Here’s the checklist:

  • Every direction gets a timestamp on the day it happens. Voice memo from the supervisor, photo of the site condition, screenshot of the email. That timestamp is your defensive record if the notice period is later disputed.
  • Notice of intention issued the same day. One-line email to the Superintendent: “This confirms our intention to claim a variation arising from your direction of [date] to [work description]. A priced claim will follow within [X] days per contract.”
  • The claim itself follows the priced-claim window. Priced against the schedule of rates where the item exists, or built up from dayworks (labour hours, plant hours, materials at cost plus margin) where it doesn’t.
  • Numbered, sequential, referenced back to the original direction. Every claim in a register that ties the direction, the notice of intention, the priced claim, and the eventual approval or rejection into one audit trail.
  • Weekly review. At the end of each week, the office walks through the register with the supervisor. Anything with a pending clock gets escalated immediately.

This isn’t revolutionary — it’s the commercial hygiene good subcontractors have always practised. What’s changed is that the tools now exist to enforce it automatically instead of relying on anyone’s memory.

FAQ

What is a time bar clause in a construction contract?

A time bar clause is a contract term requiring you to give written notice of a claim — a variation, extension of time, or delay cost — within a set number of days of the event. Miss the window and you lose the right to make the claim at all, no matter how legitimate the underlying entitlement is. Australian courts routinely enforce them.

How long do I have to notify a variation under AS 4000?

Under AS 4000-1997 clause 36.1, if the head contractor directs a variation you must give the Superintendent written notice of your intention to claim payment before starting the varied work — practically, immediately. Clause 36.4 then requires you to submit the priced claim within a reasonable time. Most amended AS 4000 contracts tighten this to a specific window such as 5 or 10 Business Days.

Can I get around a time bar with estoppel?

Sometimes. In Valmont Interiors v Giorgio Armani [2021] NSWCA 93, the NSW Court of Appeal found that where the head contractor's conduct — accepting late notices, encouraging late claims, waiving strict compliance — creates a reasonable expectation that time bars won't be enforced, they can be estopped from later insisting on them. But estoppel is expensive to prove and unreliable. The safe play is to hit the notice window every time.

Do time bars apply on Security of Payment claims?

The Security of Payment Acts (state by state) give you a statutory right to progress payment that survives most contractual restrictions — but the underlying entitlement still has to be a valid contractual claim. A variation that was time-barred at the contract level generally can't be resurrected on a payment claim. Get the contractual notice right first; SOPA is your enforcement mechanism, not your fallback.

What's the difference between a variation and an extension of time?

A variation changes the scope, method, or conditions of the work — extra concrete, a redesign, a new sequence. An extension of time (EOT) extends your date for practical completion when something outside your control (weather, late access, principal's delay) slows you down. Both have their own notice regimes and their own time bars — usually a shorter window for the initial notice and a longer window for the detailed claim.

The bottom line

A time bar clause turns a legitimate commercial entitlement into a stopwatch. Australian courts enforce them. Your head contractor’s lawyers know how they work. The only reliable protection is a workflow that captures every direction on the day it happens and issues the notice of intention before the crew has packed up for smoko.

Everything else — the pricing arguments, the estoppel defences, the SOPA claims — is trying to recover from a mistake you should never have had to make.

Varipack is the tool built for this. Your crew captures the direction on site with a voice memo and a photo. Varipack prices it against your contract schedule of rates or a dayworks build-up and drafts a numbered claim with a client approval link — before the notice period runs out. See how Varipack works →

Sources and further reading