Variations and instructions: getting paid for extra work

What is a variation?

A variation is a change to the work the contract requires: more work, less work, different work, or a change to the way, order or times in which it must be done. Most contracts allow the contractor, or the client’s representative, to instruct variations, and provide for them to be valued. Work outside anything the contract allows to be varied is not a variation at all, and may be paid on a different basis.

Get the instruction in writing

Most contracts require instructions to be in writing. On site they are often given verbally, during a walk round or in a meeting. Protect yourself:

• Confirm every verbal instruction in writing the same day: who gave it, to whom, when, where, and what it requires.
• Number your confirmations and keep a register.
• Ask for a written instruction before starting any significant extra work, ideally with your quotation accepted.

Many JCT style contracts have a mechanism for this: if an instruction given verbally is confirmed in writing within a short period (often 2 days) and the other side does not dissent within a further period (often 7 days), it takes effect as confirmed. Check your clause.

Daywork sheets

Where work is to be valued as daywork, submit daywork sheets for signature at the time, ideally the same day, showing names, hours, plant and materials. Sheets presented weeks later are easy to dispute. A signature usually confirms only that the time and resources were used, not that the work is a variation, so make sure the instruction is recorded separately.

How should variations be valued?

Many standard forms, including JCT contracts, follow a similar pattern:

• work of a similar character, carried out under similar conditions to the work priced in the contract, is valued at the contract rates;
• where the character or conditions are different, the rates are adjusted to allow for the difference; and
• where contract rates cannot sensibly be used, a fair valuation is made.

Many JCT contracts also allow work that was not itself varied to be revalued, where a variation changed the conditions under which it was carried out. Check the wording of your valuation clause.

Changed conditions: the most overlooked entitlement

Varied work is often valued at contract rates as if nothing had changed, when in fact it was done in small pieces, out of sequence, in congested or occupied areas, in winter, or at short notice. Ask whether your estimator priced the work to be done that way. If not, ask for adjusted or fair rates, and support the request with your output records: compare what your gangs achieved in disrupted areas with what they achieved where the work went as planned.

Quotations

Some contracts allow or require you to quote for a variation before it is instructed. A quotation accepted in writing fixes the price, and sometimes the effect on time, so include everything: labour, materials, plant, supervision, any effect on your programme and any disruption to other work.

Work outside the contract

If you are asked to do work that falls outside the contract altogether, it may not be a variation. Where there is no agreed price, you are generally entitled to a reasonable sum for work requested and carried out, known as a quantum meruit. Agree the price in writing before you start whenever you can.

Variations and the final account

Do not leave variations to the final account. Keep a register showing each instruction, its reference and date, your valuation, the amount agreed or disputed, and when it was included in an application. Include valued variations in each application for payment, so that any reduction has to be dealt with in a payment notice or pay less notice at the time. Watch for clauses that make a final statement or final payment notice conclusive unless you challenge it within a short period, and diarise those dates as soon as the document arrives.

Do not claim the same cost twice

If the cost of disruption is included in a variation valued at adjusted rates, keep it out of any loss and expense claim for the same period, and the other way round. Few things damage your credibility with an adjudicator more than double counting.

Keep the records

Your diary, photographs, instruction register and labour allocation records are what prove a variation and its value. See our guide to site records.

General guidance on the law of England and Wales, not legal advice. Last reviewed 2 November 2026.