Black mould: CPR Part 35 compliant quantum expert evidence

The dispute

Following completion and occupation, defects were identified
within a number of residential units, including water ingress and mould-related
issues. The employer incurred significant costs investigating the defects,
undertaking remedial works, reinstating affected areas and managing the wider
impact on residents.

The contractor disputed liability, causation and the
reasonableness of the costs incurred and invited the employer to substantiate
its position through a formal letter of claim supported by independent expert
evidence.

Our role

We were instructed to provide independent quantum expert
evidence in support of a pre-action letter of claim.

Our role was to assess the reasonableness and recoverability
of the costs claimed, review the contractual basis for recovery and provide a
clear, independent valuation capable of supporting early dispute engagement.

Our approach

We took a forensic, evidence-led approach to the valuation of defect-related losses.

We reviewed the contract, the factual background to the defects and the cost evidence relied upon in the schedule of loss. We tested whether the costs incurred were reasonable, proportionate and causally linked to the defects identified, and whether they fell within the contractual indemnities relied upon.

A key part of our approach was to test the evidential basis for each head of claim. Where costs were supported by contemporaneous records and could be clearly linked to the defects, they were included. Where the evidence was insufficient, or where duplication, betterment or proportionality issues arose, these were identified and reflected in our assessment.

This required difficult judgements and, in some instances, resulted in reductions to the sums advanced. While this was not always straightforward for the client, it ensured that the claim ultimately advanced was evidence-led, defensible and aligned with the duties of an independent expert.

The resulting valuation was presented in a clear and transparent format, enabling the opposing party and its advisers to understand precisely how the claim had been assessed and strengthening the credibility of the quantum position at a pre-action stage.

Outcome

Our expert evidence formed part of a detailed letter of claim served in accordance with the Pre-Action Protocol. It provided a structured and independent assessment of quantum that strengthened the
employer’s pre-action position and assisted in framing the dispute around evidence rather than assertion.

The case demonstrates the value of early, independent quantum expertise in complex defect matters, particularly where remedial decisions are influenced by health, safety and operational considerations and where a disciplined valuation is required before formal proceedings are commenced.