How does JCT section 5 work?
Clause 5.1 says what a Variation is, clause 5.2 sets the order of valuation by agreement, Schedule 2 Quotation or the Valuation Rules, and clauses 5.6 to 5.10 price it from bill rates outwards.
Updated: 15 September 2026. By Jack Butler-Kettle, Quantity Surveyor & Claims Consultant.
The answer
Section 5 of SBC/Q 2016 defines what a Variation is and fixes the order in which it is valued: by agreement between the Employer and the Contractor, by a Schedule 2 Quotation where the instruction calls for one, and otherwise by the Quantity Surveyor under the Valuation Rules. Clause 5.1 defines a Variation as an alteration or modification of the design, quality or quantity of the Works, including additions, omissions and substitutions, alterations of the kind or standard of materials or goods and the removal of work, and also the imposition, addition, alteration or omission of obligations or restrictions on access, working space, working hours and the order in which the work is carried out. Clause 5.2 sets the three valuation routes in that order. Under clause 5.6, work of similar character to that in the Contract Bills, carried out under similar conditions and not significantly changing the quantity, is valued at the bill rates; work of similar character but under different conditions or with a significant change in quantity is valued using the bill rates as the basis with a fair allowance for the difference; work not of similar character is valued at fair rates and prices; and omissions are valued at the bill rates. Clause 5.7 provides for daywork where the work cannot properly be valued by measurement. Clause 5.9 allows other work to be revalued where a Variation substantially changes the conditions under which it is carried out. Clause 5.10 stops any allowance in a valuation for loss and expense that would be reimbursed under any other provision of the contract, so prolongation and disruption do not belong in a Variation valuation. What goes wrong is pricing at fair rates when a bill rate applies, ignoring the fair allowance when the quantity has changed enough to affect the rate, daywork sheets for work that could have been measured, and burying loss and expense in the rate.
Example
The situation
A Variation adds 400 square metres of the same floor screed already billed at £18 per square metre, and moves 150 square metres of billed screed from a ground floor pour to a third floor with no crane access.
What happens
- The added screed is similar in character, conditions and quantity and is valued at the bill rate, £7,200.
- The third floor screed is similar in character but the conditions differ, so the bill rate is the basis and a fair allowance is added for hoisting and double handling.
- At say £4 per square metre the allowance gives £3,300 rather than £2,700.
- A further instruction to hand dig around a live service that no bill item describes goes to daywork because it cannot properly be measured.
- Any disruption to adjoining trades is claimed as loss and expense and kept out of all three figures.
The valuation in figures
| Item | Basis | Amount |
|---|---|---|
| Added screed, 400 square metres | Bill rate of £18 | £7,200 |
| Moved screed, 150 square metres, at the bill rate alone | Bill rate of £18 | £2,700 |
| Moved screed with the allowance | Bill rate plus £4 | £3,300 |
The outcome
The added screed is valued at £7,200, the moved screed at £3,300 with the allowance, and the hand digging on daywork, each on its own basis under section 5.