How to price a variation

Most variation losses come from the process around the price. The extra gets agreed on site, the price turns up weeks later, and by then the customer has forgotten asking for it. Here is a process that gets each variation priced, signed and paid while everyone still remembers why it exists.

1. Set the rules before the job starts

Tell the customer at the start how variations work: every change goes through the office, gets priced, comes back for approval, and only then gets built. A New Zealand builder who brought in a formal variation process says framing it up front means there are no nasty surprises later, and he no longer ends up eating costs because the bill arrived too late.¹

Done looks like: the variation process is written into your welcome pack or pre-start meeting, and the customer has heard it from you before the first change request.

2. Log it on site, price it in the office

Site supervisors should record requests, never agree them. A Western Australian refurbishment business fixed its missed variations with a simple chain: the supervisor logs the request, it is priced in the job software, the customer approves it, then the work is done. Each extra was only a couple of thousand dollars, but that adds up when you are running 40 jobs.²

Done looks like: every request has a log entry with the date, who asked and what they asked for, and nobody on site has quoted a price out loud.

3. Build the price like a small job

Price the variation the same way you priced the base job. Count materials, labour hours and subbie quotes, then add your overhead recovery and margin on top. Skipping overheads on extras because “it’s only small” is one way a job finishes at a lower margin than it was quoted at.

Then add time. If the change pushes the programme out, the job keeps costing you while it waits. Loan interest, council fees, insurance and supervision all carry on while no trade is on site, so put a weekly figure on an idle site and use it when a variation adds days.³ If the change extends the build, follow your contract’s extension of time notice process as well. Those clauses only protect you when you follow their notice requirements.⁴

Done looks like: a priced variation showing cost lines, overhead, margin and any time impact, with an extension of time notice issued where the contract needs one.

4. Price it fast

Speed matters because memory fades. A Sydney builder now minutes every customer meeting by email and has variations costed within two to three days.⁵ The New Zealand builder above commits to coming back to the customer the same week.¹

Builder	Region	Price turnaround	Payment terms
Northern Sydney builder	NSW	Costed within 2 to 3 days	Nothing proceeds without written approval
Wellington builder	NZ	Priced and signed within the week	Invoiced the following week
Texas remodeller	US	Signed change order before work	Larger ones paid half before, half on completion; items under about $500 absorbed

Done looks like: the customer has a written price in their inbox within a few working days of asking.

5. Check whether it changes the bank’s numbers

If your customer has a construction loan, a variation can change the stage amounts and even the valuation. A finance broker gives the example of a $15,000 tapware upgrade at stage 2: if the customer cannot cover the gap, the bank may stall the next draw. His advice is to loop in the broker and confirm where the money is coming from before you issue the variation.⁶

Done looks like: for any financed job, the customer has confirmed how the variation will be paid, and the broker or lender knows about it.

6. Get it signed before work starts

No signature, no start. If the price is not agreed in writing before the work, plan on doing it for free.

The Sydney builder learned this on a $160,000 basement excavation variation done without written sign off. He never got paid and took the loss.⁵ For bigger changes, consider taking money up front. A Texas remodeller (a US example) takes half before starting and half on completion, though he also absorbs items under about $500 by rule.⁷ Most Australian sources in our research say nothing proceeds without written approval, whatever the size, and that is the safer default.

Mobile sign off on a phone or tablet makes this quick enough that site does not have to wait.

Done looks like: a signed variation on file, dated before the work began, with payment terms stated.

7. Invoice it straight away

Bill the variation as soon as it is done, or on the next claim, rather than saving it for the final invoice. The Wellington builder invoices the week after sign off, which also stopped his crew agreeing small extras on site.¹

Done looks like: the variation appears on an invoice within a week or two of completion, and your job costing shows it as income as well as cost.

Where to next

Once the process is in place, check you are not making the common slips that undo it. Read Variation mistakes that cost you margin, then Contract mistakes builders make before they sign, because a clear scope is what every variation is measured against.

Footnotes

1. James Fell, “How James Fell Used An OVERHEAD RECOVERY MARGIN To Hit 25% Profit”, The Professional Builder (podcast), 2026. https://www.youtube.com/watch?v=AuVZltDFdac ↩ ↩² ↩³

2. Simone McKenzie, “If You Treat Your Staff Like THIS, You Will Lose Everything”, The Professional Builder (podcast), 2026. https://www.youtube.com/watch?v=3-xRfhpZnyA ↩

3. “The Hidden Cost of an Idle Site”, The Good Builder, 2026. https://thegoodbuilder.com.au/the-hidden-cost-of-an-idle-site/ ↩

4. “Construction Contracts in Australia”, The Good Builder, 2026. https://thegoodbuilder.com.au/construction-contracts-in-australia/ ↩

5. Joshua Rosinski, “How Outsourcing Administration Cut Overheads From 35% To 8%”, The Professional Builder (podcast), 2026. https://www.youtube.com/watch?v=vTe7JnQx6fg ↩ ↩²

6. “‘Money Talks, Wealth Whispers’: What Builders Can Learn From Finance Broker Barry Wilkinson”, The Good Builder, 2025. https://thegoodbuilder.com.au/money-talks-wealth-whispers-what-builders-can-learn-from-finance-broker-barry-wilkinson/ ↩

7. Chris Warren, “Stop Sweeping Extras Under The Rug Before You LOSE Money”, The Professional Builder (podcast), 2026. https://www.youtube.com/watch?v=eVauKJW-OOY ↩