Building contract variations in Queensland

A variation is any change to your building contract after both parties have signed it. In Queensland, variations to domestic building work are regulated — the Queensland Building and Construction Commission (QBCC) requires the change to be put in writing and agreed in writing before the varied work starts, with the price change, any delay and the payment timing all spelled out. Handled properly, a variation is a normal part of building. Handled loosely, it is one of the fastest ways to lose control of a budget.

What is a variation in a Queensland building contract?

Your contract describes a defined scope: a set of drawings, a specification, a schedule of finishes and a price. A variation is a documented change to that scope — adding, removing or altering work. It might be an addition (you decide the deck should run the full width), a deletion (you drop the second bathroom), or a substitution (a different cladding once the original is discontinued).

The QBCC is direct about the risk, describing changes made after a contract is signed as something that “should be kept to a minimum to avoid cost overruns and potential confusion on site”. A variation is not a failure of planning. Ten of them signed in a rush on a Friday afternoon usually is.

When is a variation legitimate?

There are three honest triggers for a variation on a Sunshine Coast or Noosa Shire job.

• You change your mind. You upgrade the joinery, move a wall, add a pool. This is the most common category and the easiest to control, because the decision is yours and the timing is yours.
• A latent condition appears. Something the builder could not reasonably have known about is uncovered. On coastal blocks that is often rock or a high water table in an excavation; on older Coolum and Noosa pole homes it is frequently termite damage, undersized bearers or non-compliant wiring found once linings come off. Renovations and extensions carry more of this risk than new builds, which is why an extension to an existing house is inherently harder to fix-price than a clear site.
• An authority requires it. A condition imposed by Sunshine Coast Council or Noosa Shire Council, a certifier’s direction, or a requirement flowing from an overlay or the Noosa Plan 2020 can force a change to approved work. See our guide to building approvals on the Sunshine Coast and in Noosa Shire.

What is not a legitimate variation is a builder recovering an underpriced tender, or charging you for work that was always in the contract documents. If a variation arrives for something already drawn and specified, ask which document it was missing from.

What does the QBCC require a variation document to contain?

Under Schedule 1B of the QBCC Act, a domestic building contract must be in writing, signed and dated by each party — and variations to it are held to their own standard. The QBCC requires the variation document to be readily legible and to state:

The builder must give you a written copy before the earlier of two moments: the variation work starting, or five business days from the day you both agreed to it. The only exception the QBCC allows is urgent work where documenting it beforehand was not reasonably practicable. The QBCC also states plainly that a builder cannot require payment for a variation before the variation work is started — variations are paid the same way the rest of the job is, through the agreed progress claim schedule.

Why must a variation be signed before the work is done?

Because after the fact, nobody is negotiating — they are arguing. Once the concrete is poured or the steel is up, you have lost the option to say no, and the builder has lost the ability to show you agreed to the cost before spending it. The QBCC’s requirement to present the variation in writing and obtain your written agreement before the varied work commences exists precisely to preserve that decision point.

It also protects the builder. A licensed builder who does extra work on a nod and a handshake is carrying unrecoverable cost and an unenforceable claim. The QBCC states that failing to properly and accurately record and approve variations before they are implemented is one of the most common causes of serious building disputes. Signing first is not bureaucracy; it is the only moment when both parties still have a genuine choice.

How do you keep variations under control?

1. Finish your decisions before you sign. Every selection resolved at design stage — tapware, tiles, appliances, external colours — is a variation that never happens. Understand what a fixed-price contract actually fixes, and what it leaves to provisional sums and prime cost items.
2. Insist on one variation register. A single running document listing every variation, its number, its price and its effect on the completion date. Reconcile it against the contract sum at every progress claim.
3. Never approve verbally. Not on site, not by phone. Email is fine — the QBCC accepts delivery in person, by post, by email, or as your contract’s notice clause provides — but it must be written and it must be agreed before the work starts.
4. Price a contingency separately. Hold your own allowance outside the contract sum for the changes you will inevitably want, so a variation is a decision rather than a crisis.
5. Ask about time, not just money. A variation that pushes out a lead time can cost you more in delay than it does in materials. The QBCC requires a reasonable estimate of the delay on the variation document, so make sure it is filled in rather than left blank.
6. Check your home warranty cover. Where variations change the value of the contracted work, the QBCC points builders to its guidance on changing or amending home warranty cover. Raise it with yours so the insured amount still matches the job.

How Roebuck Concepts handles variations

Tom Roebuck holds QBCC licence 15015060 and the company holds licence 15280811. Every variation is issued in writing, priced and dated before the work goes ahead, and tracked on a register you can see at any point. On the Grandview Drive extension at Coolum Beach — a pole home extended in every direction, and the project that won three 2025 Master Builders Queensland Sunshine Coast Housing & Construction Awards — that discipline is what made an inherently unpredictable structure manageable. You can read more about how we run a job on our build process page, or see the work on the Grandview Drive Extension project page.