Extra work and variations: how tradespeople should agree changes
Keep changes to scope, materials and price clear before they become disputes.
Applies to: UK construction and consumer work; contractual and consumer-rights details vary.
Last checked: 16 October 2026
Key points
• Explain why the extra work is needed before proceeding wherever practicable.
• Record the agreed change, cost and effect on timings in writing.
• Do not assume a customer's silence means they have agreed to a new charge.
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Typical triggers
Hidden damage, changes to specification, unforeseen ground conditions, additional preparation or a homeowner requesting something new can all create variations. They are not automatically chargeable without regard to the contract and circumstances.
A simple change record
• What the original quote included.
• What is different and why the change is necessary.
• Any extra or reduced cost and VAT treatment.
• Materials, programme and payment-stage impact.
• Customer approval before work proceeds where practical.
What if the work is urgent?
If immediate safety or damage prevention is necessary, explain and document the issue promptly. Keep safety decisions and the right to charge separate; obtain advice for a disputed contract.
Official sources
Use these official sources for the current detail that applies to your job, contract or location.
BuildPair provides general information and signposting, not legal, structural, electrical, gas or building-control approval. Requirements can change and the right answer depends on the work, contract, location and facts.
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