Values a variation priced on a daywork basis: three sections, each a prime cost plus a contractor-tendered percentage addition for incidental costs, overheads & profit.
Per the RICS Definition of Prime Cost of Daywork (3rd ed.), Labour Option A. Verify the percentages against your Contract Particulars.
For pricing guidance only: the percentage additions are contractor-tendered, not RICS figures. Always verify against your Contract Particulars.
About this dayworks valuation calculator
This free variation and dayworks valuation calculator prices work executed on a daywork basis under a building contract. Used to value an instructed variation that cannot fairly be measured and rated. It builds the account from the three standard sections. Labour, Materials & Goods and Plant, taking the prime cost of each and adding the contractor's tendered percentage for incidental costs, overheads and profit. It is aimed at UK contractors, quantity surveyors and site managers pricing dayworks at tender or interim valuation. The percentage additions are editable because they are contractor-set figures from the Contract Particulars, not fixed rates. All figures exclude VAT.
How a dayworks valuation is calculated
The method follows the RICS / Construction Confederation Definition of Prime Cost of Daywork (3rd ed., 2007), using Labour Option A, a percentage addition on the prime cost of labour. Each section total is prime cost × (1 + addition% ÷ 100), with labour prime cost taken as operative hours × all-in rate. The three section totals are summed to give the daywork value, which equally equals total prime cost + total additions. For example, 16 hours at £25/hr plus 15% gives a £460 labour total; £480 of materials at 10% gives £528; £350 of plant at 10% gives £385, a daywork value of £1,373 (£1,230 prime + £143 additions).
Frequently asked questions
What percentage additions should I use?
There is no standard figure, the RICS Definition leaves the percentages for the contractor to insert in the Contract Particulars at tender. Use the percentages stated in your contract; the defaults shown are neutral placeholders for illustration only.
What is the difference between Labour Option A and Option B?
Option A applies a percentage addition to the prime cost of labour, the basis this calculator uses. Option B instead uses all-inclusive labour rates with no separate addition. Check which your Contract Particulars specify before pricing.
Does the daywork value include VAT?
No. The value is calculated net of VAT. Add VAT at the prevailing rate at the application or invoice stage as appropriate to the contract.