Variations: where the economics of a job quietly change, and how to control them without blocking change

Change is normal. Customers refine what they want, designs are completed or corrected, site conditions reveal surprises, regulations shift. A job that never changes may simply be one where nobody is learning. The problem is not change itself. It is how change gets agreed: verbally, on the spot, without a price, by whoever happens to be asked. Jobs rarely lose money through one dramatic variation. They lose it through many small decisions that become irreversible before anyone sees their combined effect.

A variation is not just an instruction to do different work. It is a decision to change the commercial basis of the job: what is being delivered, for what price, by when, with what risk. Treated as paperwork, variations accumulate without anyone seeing the whole picture. Treated as small investment decisions, they can be approved, deferred or declined deliberately, with their full consequences in view.

This article explains how to tell different kinds of change apart, why price and time should be agreed before work proceeds, how to see the full effect of a change, why timing matters so much, and how to learn from the pattern of changes across jobs. It applies whether you are the contractor or the customer. It is general information. Variation rules depend on the contract, and some laws, including residential building laws in several states, set specific requirements for how variations must be agreed; check yours, and get advice on disputes.

Three kinds of change

Before deciding anything, identify what kind of request it is:

• Correction: the agreed requirement has not been met. The question is usually who is responsible and how the fix is handled, often under warranty, not a new price.
• Controlled change: the agreed requirement, design, method or timing is being altered because of new information or a new decision.
• Enhancement: something extra beyond the agreed scope.

The labels matter commercially. Calling a defect an enhancement can shift cost unfairly onto the customer. Calling an enhancement a “clarification” lets scope expand without anyone consciously agreeing to pay for it. And well-meant additions that nobody asked for, sometimes called gold plating, can create training, support, warranty or compliance obligations. More is not automatically better.

Common misreadings

• Small changes are low risk. A change that is cheap on its own can trigger delay, rework, ordering changes or effects on other trades that cost far more.
• Price can be sorted out later. Once labour and materials are committed, leverage on both sides falls and disagreements become disputes.
• A quick verbal request is just coordination. A direction that changes the work can have commercial consequences even if nobody used the word “variation”. Whether it does depends on the contract and the law, which is exactly why it should be recorded.
• Only customer requests are variations. Design corrections, consultant changes and new external requirements change the job too.
• Each variation stands alone. The question is also what all the changes together are doing to the job’s original economics.

Agree the five essentials before work proceeds

For each change, establish:

1. Cause: why is it needed?
2. Authority: who can approve it under the contract?
3. Scope: what drawing, specification or requirement changes?
4. Cost: the direct cost and any knock-on costs.
5. Time: the effect on the programme and completion date.

For larger changes, add a sixth: benefit. Does it improve, protect or weaken what the job is meant to achieve?

Agreeing these before work proceeds creates a window in which the customer can understand the consequences before committing. Some changes are genuinely urgent, such as safety issues or work that will otherwise stop. Those need a fast route, not no route: urgency should shorten the process, not remove the record. Even a phone photo of a signed note, followed by a proper form the same day, is far better than nothing.

See the whole effect

The visible price is often only part of the cost. A change can affect:

• design and drafting time;
• ordering and supplier arrangements;
• the sequence of work and the critical path;
• testing, inspections and approvals;
• training, procedures and maintenance;
• drawings, records and manuals;
• other jobs competing for the same people;
• benefits delayed, increased or put at risk.

Make opportunity cost visible too. Approving a change may use the only available specialist for a week, extend hire of equipment or delay another customer’s job. Those costs often sit outside the job’s budget but are real. Where a change also moves the completion date, the when the job runs late article covers keeping the time effect properly recorded. For significant changes, record what approval gains, what rejection protects, what else is displaced and the latest date a decision can be made.

Timing changes everything

The cost of changing direction rises as work progresses. A layout change during design means revising drawings. After ordering, it means renegotiating with suppliers. After installation, it means rework, extra testing and possibly delay. The same request can cost several times more depending on when it arrives.

So the useful question is not only “can we do this?” but “is this the right time to do it?” Some good ideas are better deferred to a later improvement once the current job is complete, because changing now would cost far more than the benefit.

A one-page variation record

A simple form, completed before work proceeds, does most of the work:

Agreeing a schedule of rates at the start of the job, for common items such as an extra power point, a metre of cabling or an hour of a tradesperson’s time, makes small variations quick to price and hard to dispute.

Approval is not the end

An approved change means nothing operationally until everything affected is updated: drawings, specifications, work instructions, orders, the schedule, the budget, the risk list and the acceptance criteria. If the drawing changes but the instruction on site does not, approval has produced inconsistency rather than control. Keep one current version of each controlled document and make sure superseded versions are clearly marked.

Beware “approved, details to be worked out later”. It often transfers risk silently to whoever has to do the work.

Track the cumulative position

Each variation looks reasonable against the job as it stands. Nobody sees the total unless someone adds it up. Keep a simple register showing every change, its cost and time effect and a running total against the original contract. Agree in advance a point at which the total triggers a broader conversation about the job as a whole. The keeping the record of what you promised article covers keeping an unchangeable record of the original commitment alongside the working plan.

Learn from the causes

A register that records only prices misses its most useful information: why changes happened. If most changes come from the customer’s late decisions, scope was not settled early enough. If most come from design corrections, the design was issued before it was mature. If most come from unforeseen conditions, investigation before pricing may have been too thin, or the risk allocation may be working as intended. Measure your own pattern across jobs and fix the cause, whether in briefing, design, investigation or contract terms.

If you are the customer

Customers have as much to gain from controlling variations as contractors do. A few habits help:

• Name one person who can request and approve changes, and tell your staff and other contractors not to instruct workers directly.
• Ask for price and time before approving, even for small items. Most contractors can turn around a quick quote.
• Set aside a change budget for the job, separate from contingency for unexpected problems, so that improvements are decided against a known limit.
• Settle requirements early. The cheapest variation is the one decided before design is finished.
• Ask why when your contractor proposes a change. Is it a correction of their own work, a consequence of your decision, or something unforeseen?
• Keep your own copy of every approved variation and the updated drawings.

A worked example

This is an illustration. A small electrical contractor is wiring a café fit-out for a fixed price. Over three weeks, the café owner and the shopfitter make several requests directly to the electricians on site: six extra power points, relocating the coffee machine circuit, under-bench lighting and two extra data points. The electricians, wanting to help, do the work. When the contractor invoices about $7,800 in extras at the end, the owner disputes several items, saying they were “part of the job” or “only small”.

For its next jobs, the contractor introduces a one-page variation form and a simple rule: no change is carried out without a recorded price and the customer’s approval, except genuine urgent safety work, which is recorded the same day. Each request is classified:

• Correction: a circuit installed to the wrong location because of the contractor’s own misreading of the drawing, fixed at no charge.
• Controlled change: the coffee machine moved because the owner changed suppliers.
• Enhancement: under-bench lighting not in the original scope.

The contractor also shows the customer the effect of timing. On the next job, relocating a circuit before tiling is quoted at about $600; the same change after tiling would cost about $1,900 because of making good. The customer decides early.

After six months, the contractor reviews causes. Of 40 recorded variations, most came from incomplete shopfitting drawings. The contractor now asks for a pre-start coordination meeting with the shopfitter and owner on every fit-out, and disputes over extras largely disappear.

How this applies to a small Australian business

• Classify each request: correction, controlled change or enhancement.
• Agree cause, authority, scope, cost and time before work proceeds.
• Create a fast route for urgent changes that still leaves a record.
• Look beyond the direct price to knock-on and opportunity costs.
• Show the customer the cost of timing, and defer where sensible.
• Update every affected document after approval.
• Keep a running total against the original contract.
• Review causes across jobs and fix the source.
• Check legal requirements for variations in your industry and state, especially for residential building work.

Signals worth watching

• Requests made directly to workers on site.
• Extras invoiced at the end and disputed.
• Variations with no recorded cause.
• Drawings and site instructions out of step.
• Many small changes and no running total.
• The same causes of change on job after job.

Common mistakes

• Doing the work first and pricing it later.
• Treating verbal requests as harmless.
• Calling enhancements clarifications, or defects enhancements.
• Ignoring knock-on costs and timing.
• Approving changes without updating documents.
• Never asking why changes keep happening.

Frequently asked questions

Won’t a formal process annoy customers? Most customers prefer knowing the price before they commit. A short form and a quick quote usually improve the relationship.

What if the customer refuses to pay for a change already done? That is why approval should come first. If it has already happened, gather your records and refer to your contract’s dispute process; get advice if needed.

Who on site can approve changes? Only the people named in the contract. Tell your team who that is, and make it easy for them to direct requests to the right person.

What if the change is urgent? Do what is needed for safety, record what was asked, by whom and when, and confirm the price as soon as possible.

How do we price small variations quickly? Use a schedule of rates for common items, agreed at the start of the job.

Should every change go to the owner of the business? No. Set limits: the project lead can approve changes up to an agreed value that keep the margin intact, with larger or margin-reducing changes going higher. The aim is speed with a record, not more approvals.

Questions to ask

• Is this a correction, a change or an enhancement?
• Who can approve it, and has price and time been agreed?
• What else does it affect beyond the direct work?
• Is now the right time to make this change?
• What is the running total of changes against the original contract?
• Why do our jobs keep changing, and what can we fix upstream?

Bringing it together

Variations are where the economics of a job quietly change. Classify each request, agree cause, authority, scope, cost and time before work proceeds, and give urgent changes a fast route that still leaves a record. Look at the whole effect, including knock-on costs, opportunity cost and the cost of timing, and update every affected document once a change is approved. Keep a running total against the original, and learn from the causes so fewer changes are needed next time. Change handled deliberately protects both margin and the relationship.

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Source: KEVOS notes, drawing on teaching material on change control, configuration management and variations under standard construction contracts. Examples and figures in this article are illustrations. This article is general information, not legal advice.