Focusing quantum evidence on the issues remaining before mediation

We supported a contractor and its legal advisers with independent quantum evidence for a mediation over alleged design defects. A claim of around £0.6 million appeared to be separated from the other expert’s assessment by several hundred thousand pounds. Our review showed that much of that apparent gap concerned responsibility rather than the value of the work, allowing the remaining quantum issues to be addressed through a focused valuation reconciliation.

Background

The dispute concerned additional work and delay associated with alleged design defects. The claim included changes to walls and door openings, associated finishing work, management costs and prolongation. The parties needed to understand the value of the disputed work alongside the separate questions of technical responsibility and delay.

A full narrative report repeating substantially aligned valuations would have added time and cost without necessarily helping the mediation. The immediate task was to establish which financial differences were genuine and where the figures reflected different assumptions about liability.

Our approach

We worked through the other expert’s report and detailed appendices, reconciling each item against the contractor’s claim. We separated the headline assessment from the alternative values that applied if responsibility for the underlying defects was established. On a comparable quantum basis, the initial difference was below £100,000, substantially smaller than the headline positions suggested.

That review shaped the form of our evidence. We advised that a valuation reconciliation would be more proportionate than a lengthy report covering areas of agreement. The resulting schedule set out the claimed amounts, the other expert’s assessments, our supplementary valuations and the reasons for the remaining differences.

Where work had clearly been carried out but the available cost records were incomplete, we tested a reasonable valuation against the evidence. This included photographs, payment information, quantities and descriptions of the activities, supported where appropriate by published rates and sample daywork records. Assumptions about labour, time and quantities were explained alongside the calculations.

The assessment also considered overlap between individual cost items, management allowances and prolongation. This kept the valuation focused on additional work supported by the material available and made clear where further substantiation was needed.

We reviewed the prolongation day rates separately. The comparison distinguished costs that varied with time from fixed costs and checked the calculations behind the monthly figures. Once the independent delay expert’s report was available, we applied the appropriate daily rates to the periods allocated to three delay events. That produced a prolongation assessment of approximately £115,000.

The timing of the records required care. Some delay periods preceded the earliest cost information supplied, so we used the nearest available period and explained that assumption. For a later event spanning several months, the calculation used an average across the relevant available months.

When further delay material and comments from the other expert required a response close to the mediation, we updated the valuation and prepared a concise explanatory letter within two days. The letter explained the reconciliation approach, the basis of the supplementary allowances and the revised prolongation assessment.

Outcome

The legal team received an itemised quantum reconciliation, supporting calculations and a written explanation of the expert approach for use in the mediation process. It could distinguish genuine valuation differences from issues that depended on technical responsibility or delay evidence.

Our contribution was to concentrate the expert work on the matters that needed to be resolved. The format made the numerical positions transparent and gave the parties a practical basis for narrowing the quantum issues, while keeping the evidential assumptions visible.