Direct costs

Direct costs are what unit rates are made of: the crew hours to place the concrete, the concrete itself, the pump that placed it. They scale with quantities — more metres of pipe means proportionally more direct cost — which is what makes them measurable, priceable per unit, and comparable between bidders.

The boundary between direct and indirect is a matter of convention, not physics, and that is where comparisons break. One contractor treats scaffolding as a direct cost within the rates; another carries it in site overheads; a third prices it as a separate preliminaries item. All three tenders are legitimate and none are comparable line by line. Estimates and bids should state where the boundary was drawn, and bid levelling exists largely to redraw it consistently before prices are compared.