Unit Rate Contract

A road contractor prices excavation at $20 per cubic metre, and the estimate assumes 1,000 cubic metres, but verified final work is 1,200, so under a simplified unit-rate arrangement that line becomes $24,000 rather than $20,000. RICS guidance on contract selection explains remeasurement contracts that value work carried out at tendered rates and settle the final sum after actual quantities are measured.

RICS guidance on interim valuation discusses measuring and paying work as it proceeds, although an interim certificate is not necessarily a final measure or acceptance of every quantity, and the exact contract clauses control a particular project. Define work items precisely, because excavation in rock and ordinary soil may have different rates and a broad item can cause dispute when conditions vary.

Set the measurement rules so that gross volume, net volume, deductions, waste and survey methods are known before work begins, since two parties measuring differently can produce different totals. State what each rate includes, as labour, plant, materials, overhead and profit may be included or separated, and compare offers on the same scope.

Record estimated quantities, but remember that a bill may help compare bids without being a promise that every estimated unit will occur, since risk allocation follows contract terms. Verify actual quantities with site surveys, measurement sheets, drawings and joint records, because a contractor invoice alone is not independent measurement or a final certified quantity.

Quality matters too: units that fail specification may not be accepted or payable in the same way as compliant work, so measurement and acceptance are related but distinct. An illustrative line value is accepted quantity times applicable rate, so 1,200 cubic metres at $20 equals $24,000, before other items, variations and taxes.

Watch quantity changes, since a large increase or decrease may trigger rate adjustment under some contracts, and do not assume the original rate always applies without reading the terms. New tasks not in the schedule may need agreed rates, valuation formulas or change orders, so do not force unlike work into an existing item.

If quantities rise, the client may need revised funding even though unit rates are unchanged, so cost and cash forecasts should be updated before the final contractor invoice arrives. Measured work to date may be paid periodically with retention or other deductions, and later correction of measurement may be possible under the terms.

Preserve evidence such as daily records, surveys and approvals, because estimates reconstructed at project end are harder to defend, and resolve discrepancies promptly while the work remains visible, since arguments after backfill or concealment are harder. Compare with a lump-sum contract, which generally fixes a price for a defined scope under its terms, whereas a unit-rate arrangement directly exposes the final value to measured quantity; both can include variations.

A unit rate can reward efficient unit production but may not control total volume, so scope and quality oversight remain important. A client may also set authorisation limits or require notice before quantity thresholds are exceeded, because a rate schedule alone is not unlimited spend permission, and for owners the contract prices work per measured unit and needs sound definitions and quantity controls to manage the final bill.