Variations (Construction)

Variations are inevitable in construction. No matter how thorough your documentation is, something will change. The council might require a design modification after DA approval. The client might want upgraded finishes. You might hit rock where the geotech report said there'd be clay. Every one of these changes needs to be formally documented as a variation — and if it isn't, you're exposed.

There are three types of variation you'll encounter on a typical project. Directed variations are changes the principal instructs — you want a different tile, you want the layout adjusted, you want an additional power point. These are straightforward because you initiated them. Constructive variations are murkier. The contractor claims that work they performed was outside the original scope, even though you never issued a direction. Maybe the drawings were ambiguous, or the specification contradicted itself. The third category is latent conditions — physical conditions on site that differ materially from what was reasonably foreseeable. Think contaminated soil, unexpected underground services, or rock where the geotech said sand. Under most Australian standard form contracts, latent conditions entitle the contractor to additional cost and time whether you like it or not.

The formal variation process follows a predictable workflow: notice, assessment, direction, and valuation. It starts when either party identifies a change. The contractor gives written notice that they consider certain work to be a variation. The superintendent then assesses whether the claim is valid — does this work actually fall outside the contracted scope? If it does, the superintendent issues a direction confirming the variation and the contractor provides a quotation. That quotation gets assessed, negotiated if needed, and either approved or rejected. Finally, the approved variation gets valued and incorporated into the next progress claim.

Here's where Australian standard form contracts differ. Under AS4000, the superintendent can direct a variation and the contractor must comply, even if the price hasn't been agreed yet — valuation happens after the fact. AS2124 works similarly but with slightly different notice periods. HIA contracts, common on residential projects, give the builder more latitude to claim variations for anything not explicitly shown on the drawings. Each contract allocates risk differently, so you need to know which form you're working under before you push back on a variation claim.

The financial impact of variations compounds in ways that catch developers off guard. One $5,000 variation feels manageable. But twenty of them across a twelve-month build adds up to $100,000 on a $1M contract — a 10% cost blowout that can destroy your project margin. It gets worse. Each variation that adds time also adds holding costs: interest on your development finance, extended site prelims, superintendent fees, and delayed settlement income. A $15,000 variation that extends the program by two weeks might actually cost you $40,000 when you factor in the time impact.

Documentation is your single biggest protection. Every variation should have a written notice, a clear description of the changed work, a cost breakdown, a time impact assessment, and a formal approval or rejection. If you're relying on verbal agreements or email threads buried in someone's inbox, you're building a dispute file, not a paper trail. The contract will specify notice periods — typically 5 to 14 days — and if either party misses them, they can lose their entitlements. Courts and adjudicators take notice requirements seriously.

Variations flow directly into progress claims. Once a variation is approved, the contractor includes it as a line item in their next payment claim. The superintendent certifies it (or adjusts the amount), and it gets paid. This is why your variation register and your claim register need to talk to each other. If they don't, you'll either overpay — certifying work that was never formally approved as a variation — or underpay and trigger a payment dispute under security of payment legislation.

Watch for common contractor tactics. Scope creep is the most frequent: the contractor does extra work without notice, then drops a bulk variation claim months later when it's too late to verify quantities. Another favourite is the "shotgun" approach — submitting thirty minor variations hoping you'll approve most of them without scrutiny. Some contractors deliberately price the original tender low, knowing they'll make their margin on variations. And be wary of time-based claims disguised as variations — the contractor claims a disruption variation when what they're really after is an extension of time to avoid liquidated damages.

So when do you push back, and when do you accept? Push back hard when the work was clearly within the original scope, when the contractor hasn't followed the contractual notice process, or when the pricing is inflated beyond reasonable rates. Accept the variation — and manage it tightly — when the change is genuinely outside the original scope, when you directed the change yourself, or when a latent condition has been properly documented. The worst thing you can do is ignore a variation claim and hope it goes away. Unresolved variations stack up and become the basis for a final account dispute that costs far more to resolve than the original claims were worth.