Variation
Plain English. Practical detail. UK context.
A variation is a change to an agreed scope or specification. It can affect cost, time, sequencing and the work of other trades, not just the item being changed.
Last reviewed: (editorial review against the public sources listed below).
What it means in practice
Record the requested change and its consequences before carrying it out where practicable. Identify revised materials, labour, programme effects and any work made redundant. Follow the change procedure in the relevant contract rather than treating every site conversation as an approved instruction.
Distinguish correcting defective work from a customer-requested change. Both can alter the activity on site, but their commercial treatment is not automatically the same.
For homeowners
Ask for the price and programme implications of a change before agreeing it. Moving a socket, changing a shower or altering an opening can affect concealed work already completed. Keep the revised description with the original scope so there is a shared record of what the final project should include.
Practical checks
Use dated written confirmation and make clear who is authorised to agree changes. For an urgent safety issue, make the site safe first and document what happened promptly.
A change record should show the whole consequence
Moving a shower after first fix can affect pipes, waterproofing, electrical zones, tiling and the programme, not just the new tap position. Record the original requirement, proposed replacement and any abandoned materials or work. Identify whether a designer or specialist needs to approve the revised arrangement. A customer should be able to understand the combined effect before accepting the change. A tradesperson should distinguish a genuine new request from correcting their own non-compliant or defective work. Calling both an extra does not decide who should pay. Where timing is urgent, explain the available safe options and record what was authorised as soon as practicable.
Authority and consumer protection
Follow the actual contract's instruction and valuation process. Citizens Advice explains the importance of agreeing extra domestic work and its cost rather than simply increasing an accepted quote. A conversation with someone visiting the site may not be an instruction from the person authorised to change the contract. Agree that authority at the start, including how drawings or messages are confirmed. A variation also cannot waive building safety requirements or make a regulated task suitable for an unqualified person. Keep a running revision record so the final handover and invoice match the work agreed, not a mixture of old and new versions.
Frequently asked questions
Is every extra task automatically an approved variation?
No. Approval and valuation depend on the agreement and circumstances. Record the change, who requested it and the agreed consequences rather than relying on assumptions.
Does a verbal request always approve the price?
Not necessarily. Record the requested scope, who authorised it and the agreed price or valuation basis. The contract and circumstances determine the position if disputed.
Useful Trustmark resources
Sources and further reading
Public sources and further reading. Sources checked: 8 November 2026. Consult the original for details and later changes.