Building Variations Explained: What “Extras” Really Mean in Construction

Even with the most thorough planning, changes during construction are almost inevitable. While the design is usually finalised and agreed before tenders are called or a building contract is signed, variations allow projects to adapt to unforeseen conditions or evolving needs without derailing the process.

What Is a Variation?

A variation is a change to the type, extent or quality of work set out in the building contract. Variations typically arise where the physical building works need to be altered from what was originally documented.

Changes may be triggered by new information, site conditions or design refinements, and they generally affect either the cost of the project, the construction timeframe, or both.

Why Do Variations Occur?

Some variations are unavoidable. Conditions may be discovered on site that were concealed or could not reasonably have been anticipated at the time of tender. A common example is the discovery of rock during excavation, which can increase excavation costs and delay progress.

Variations can also arise from requirements imposed by authorities after construction has commenced, or from issues uncovered in existing buildings during renovation work. In other cases, changes may simply result from the owner reconsidering aspects of the design once the building starts to take shape.

Can I Change My Mind During Construction?

Most building contracts allow owners to request changes, usually through the architect in architect-administered contracts. While this flexibility can be valuable, it should be exercised carefully.

Variations almost always increase costs and frequently extend the construction program. Even small changes, such as relocating a door or altering a finish, can have knock-on effects if materials have already been ordered or work has commenced. For this reason, it is strongly advisable to resolve as many design decisions as possible before tenders are called. Where uncertainty remains, it is sensible to allow for potential variations within your budget.

Contingency Sums

To manage the financial impact of variations, your architect may recommend including a contingency sum in the project budget. This is commonly between 5% and 10% of the construction cost, and sometimes higher for renovation projects where unknown conditions are more likely.

The contingency sum can be included in the building contract or held outside it as part of your overall project budget. In either case, the funds can only be used with your approval. If included in the contract, any unused portion is typically deducted from the final payment to the builder.

How Are Variations Managed?

Building contracts set out clear procedures for dealing with variations. Where a variation is required, it should be requested and authorised through your architect. Your architect will usually seek a quotation from the builder. So that the cost and time implications are understood before the change proceeds.

In some situations, particularly where urgent work is required, it may not be possible to agree on the price immediately. Most contracts allow the architect to later assess and certify a fair and reasonable cost. However, domestic building legislation in many Australian states requires variation costs to be agreed in writing before the work is carried out wherever possible.

In Summary

Variations are a normal part of the construction process. Some are unavoidable, while others are a matter of choice. Before approving a variation, it is important to understand both the cost and time consequences. Your architect’s role is to manage variations in accordance with the building contract and relevant legislation. This helps to protect your interests and keep the project on track.

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