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Variations and extras: how changes are priced and agreed

A variation is a change to the agreed work, dealt with under the contract's change procedure. Record the instruction, price basis and programme effect before proceeding wherever possible, rather than leaving an informal request to become a disputed extra.

RICS's guidance on valuing change distinguishes the scope change from the process used to assess its financial effect. [1]

Start with the original agreement

Compare the requested work with the signed scope and latest authorised drawings. A genuinely new client choice, expenditure of a provisional sum and correction of non-compliant work raise different questions. RICS treats changes and allowances separately in cost reporting; defective consumer services can engage statutory remedies rather than merely becoming another chargeable option. [2] [3]

Where the contractor says something was excluded, ask them to identify the relevant document and wording. Where the client requests a change, identify exactly which part of the earlier requirement is being replaced. This is a practical way to avoid debating an “extra” without first establishing the baseline.

Use a short change record

A useful instruction records:

  1. The change number and reason.
  2. The drawing, specification or location affected.
  3. The proposed price or agreed method of valuation.
  4. Any effect on completion and related work.
  5. The person authorising it and the date.

Use the communication and authority arrangements in the contract. RICS's valuation guidance and JCT's commentary on contract notices underline why both the substance and method of communicating an instruction matter. [1] [4]

Agree money and time separately

Ask for a breakdown of the labour, materials, plant and additions in the proposed price. Where payment will be based on recorded time and resources, agree the recording and approval process before authorising that work. Request supporting records with each assessment and identify any disputed entry promptly.

A price agreement does not, by itself, explain whether the completion date changes. Record that separately and ask for the programme effect. RICS's extensions-of-time guidance distinguishes delay assessment from a general statement that work has changed. [5]

Check technical implications

Before authorising the change, ask the design team whether it affects structural design, fire precautions, services coordination or approval requirements. Designers and contractors have building-regulations duties for the work they undertake; a commercial instruction is not evidence that the altered design complies. [6]

Keep separate totals for approved changes and changes still awaiting a price or decision. Ask the contractor to reconcile those lists with each payment request and mark any newly added item for review.

For consumer work, relevant information relied on when contracting can be binding under section 50 of the Consumer Rights Act. Preserve the original promises and the express agreement to subsequent changes. [7]

Sources 7 references
[1]
Valuing change

RICS · accessed 2 Oct 2026

[2]
Cost reporting, 1st edition

RICS · accessed 2 Oct 2026

[3]
Consumer Rights Act 2015, section 55: Right to repeat performance

UK Parliament / legislation.gov.uk · accessed 2 Oct 2026

[4]
The JCT Design and Build Contract (2024 Edition) – A Year On

The Joint Contracts Tribunal · accessed 2 Oct 2026

[5]
Extensions of time, 1st edition

RICS · accessed 2 Oct 2026

[6]
Design and building work: meeting building requirements

Building Safety Regulator / GOV.UK · accessed 2 Oct 2026

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