How do you price a variation — BOQ rates, star rates, or cost-plus?

The hierarchy, and why it exists

Most standard forms set out a valuation hierarchy, and it runs from most objective to least. Where the varied work is of the same character and executed under similar conditions, the BOQ rates apply — no negotiation, no argument, the rate is the rate.

Where the work is similar but the conditions differ, the BOQ rates form the BASIS of a new rate — a star rate, derived and adjusted rather than invented. And only where the work is genuinely unlike anything in the bill does valuation fall to actual cost plus a margin.

The hierarchy exists because each step down gives away objectivity. A BOQ rate was competitively tendered. A star rate is argued. A cost-plus valuation is whatever the timesheets say, with no incentive to be efficient.

Where the money actually moves

The fight is almost always about step two: is this the same work under similar conditions, or is it similar work under different conditions? Pouring the same slab at night, in a confined area, after the crane has been demobilised, is not the same work — but the employer will say it is, and the BOQ rate is the cheaper answer.

Which is why the conditions must be documented at the time. "Executed under similar conditions" is a question of fact, and the contractor who recorded the access constraints, the sequence disruption and the plant availability has a case. The one who did not is arguing from memory against a rate that was competitively tendered.

And on dayworks, the sheet is the entitlement

Cost-plus valuation is done on daywork sheets: who was there, for how long, with what plant and materials. And an unsigned daywork sheet submitted at the end of the month is an assertion, not a record.

Get them signed at the time, by someone with authority. This is the single most commonly lost entitlement in construction, and it is lost for the most mundane reason imaginable: nobody wanted to chase a signature on a Friday.