The job is halfway through, someone says “while you’re here”, and suddenly the clean little contract you started with is gone. A bit more tiling. Another power point. Shift the vanity. Box that pipe in too. None of it sounds huge on its own, but this is where good jobs start getting messy and where trades end up doing work they never really got approval for.
Here’s how to handle extra work on site properly, what the official building guidance says about variations, and how to stop a small change turning into a proper fight.
Treat “while you’re here” like a contract moment
The mistake is treating extra work like a casual favour instead of what it actually is: a change to the deal. The words might be relaxed, but the consequences usually are not. A customer thinks they asked a quick question. A tradie thinks they got a verbal go-ahead. Two weeks later the invoice lands, the price feels different from what was imagined, and both sides are suddenly certain the other one is being unreasonable. If the scope changes, even a little, treat it as a variation and slow the conversation down.
The official pattern is simple: write it before the work starts
Across the official guides in NSW, Victoria and Queensland, the same pattern keeps showing up. NSW says variations must be in writing, attached to the contract, and signed before the work starts, except in urgent safety or damage situations. Victoria says major domestic building variations need to be agreed in writing and include the changed price and completion date before the work commences. Queensland says the contractor must give the variation in writing before the variation work starts, or within five business days of agreement at the latest, and the owner must respond in writing. Different systems, same message: do not rely on a chat beside the scaffold.
A proper variation has three parts
If you want the extra work approved cleanly, three things need to be on the page. First, what is changing. Not “extra joinery”. Say which cabinet, what finish, what hardware, and what is removed or replaced. Second, what it does to the price. Not “about another fifteen hundred”. Show the amount or the method of calculation. Third, what it does to time. If the change adds four business days because the new stone has a lead time, say so. Scope, money, time. If one of those is missing, the argument has already been booked in for later.
Urgent safety work is the narrow exception, not the habit
Most variation rules leave a small door open for urgent situations. NSW allows paperwork after the fact where there is likely danger to someone or damage to property. Queensland says there is an exception where urgent variation work is needed and it is not reasonably practicable to get the written document done first. That makes sense. If a rotten beam is about to fail, nobody wants a paperwork lecture before the temporary support goes in. But this is a narrow exception, not a lifestyle. “We were already here” is not an emergency. “It was easier just to keep going” is not an emergency either.
If the change fixes your mistake, don’t call it a variation
This is where plenty of relationships go bad. Official guidance in NSW is blunt on the point: if the reason for the variation is the builder’s or tradesperson’s fault, the owner does not have to pay the extra cost of fixing it. That is fair. A variation is not a clean-up fee for work that should have been allowed for, measured properly, or done right the first time. If a tradie underquoted because they missed something obvious, trying to relabel that miss as a variation only tells the customer the rest of the job will be the same story. Own the mistake early and you are much more likely to keep the trust.
Customers should stop saying yes in the doorway
Customers create plenty of this chaos too. A tradie points at a better idea on site, you say “yeah, go on then”, and later you are annoyed that the yes turned into a bill and a delay. If you are the owner, slow your own mouth down. Ask for the variation in writing. Ask what it does to the price and completion date. If the change is genuinely tiny and both of you are calm, you might still sort it quickly, but the habit should be the same every time. Small verbal approvals are how people sleepwalk into larger written disputes.
Tradies should stop carrying extra work on goodwill
From the trade side, the biggest trap is momentum. You are on site, the tools are out, the customer seems happy, and it feels awkward to stop and do the paperwork for what looks like half an hour’s extra work. Then the half hour becomes two hours, then materials, then a return visit, then a grim conversation about why the customer “thought it was included”. Good operators do not bill off vibes. They pause, describe the change, get approval, then restart. It is less romantic than a handshake, but it is how you get paid without poisoning the job.
A good variation should feel boring
The best variation documents are dull. That is the point. They say what changed, what it costs, how long it adds, and who approved it. They do not leave one side relying on memory, tone, or a phone call from three Fridays ago. In Victoria, even where the law allows a narrow shortcut for very small owner-requested changes, the official guidance still recommends putting prime cost items, provisional sums and other changes in writing to avoid disputes. Boring paperwork is not a lack of trust. It is what trust looks like once money is involved.
If the job changes, do not treat that as a side conversation to the real contract. It is the real contract now. Write the change down, attach the price and the extra time, and get the approval before the work starts unless it is a genuine emergency. That small pause saves a lot more than it costs.