Variation control after award: instructions, new rates, dayworks and final account

Variation management should begin before the price is agreed. The first question is whether a communication actually instructs a change, requests a proposal, clarifies existing scope or records a site condition. Acting on an ambiguous instruction can create disagreement about entitlement; refusing necessary work while waiting for commercial agreement can create a different project risk. A controlled instruction register makes the status explicit.

Scope definition is essential before valuation. The team should identify drawings, specifications, quantities, interfaces, temporary works, testing, programme effect, procurement impact and omitted or replaced work. A variation quotation that prices only the visible new material can miss design hours, mobilisation, disruption, changed access, additional testing and downstream subcontract effects.

Existing BOQ rates may remain applicable where the work is genuinely comparable and the contract criteria for rate application are satisfied. Where character, quantity, conditions or timing change materially, a new rate may be required under the governing contract. The build-up should show labour, equipment, material, subcontract, indirect cost and applicable mark-ups so the valuation can be reviewed rather than negotiated as an unsupported lump sum.

Dayworks require disciplined records because valuation depends on actual resources. Labour categories and hours, equipment, materials, invoices, signatures, dates and work descriptions should be captured daily and submitted within the required contractual period. A technically valid daywork performed without contemporaneous signed records can become commercially difficult to recover.

Upstream and downstream positions should be reviewed together. The main contractor may have a variation claim against the Employer while simultaneously receiving a subcontract variation, acceleration request or disruption notice. The net commercial position depends on what is recoverable upstream, what is payable downstream and whether the subcontract terms correctly flow through notice, valuation and programme obligations.

Final account should not be postponed until the end of the project. Each variation should progress through identification, instruction, quotation, assessment, agreement, certification and close-out while evidence is current. A live final-account forecast combines measured work, approved and pending variations, claims, provisional sums, retention, securities and downstream liabilities. This reduces the risk that project completion is followed by years of reconstructing commercial history.