NEC4: Disallowed Cost Explained

6 May 2026 · 62 min
1:02:03

This NEC4 webinar, hosted by Glenn Hyde (GMH Planning) with presenters Ben Walker (Gather) and David Allen (SECA Southern), provides a detailed walkthrough of the concept of disallowed costs in cost‑reimbursable NEC4 contracts (main options C, D, E and, briefly, F). The session defines disallowed costs, explains why they are built into the contract as a commercial control mechanism, and shows how they are incorporated into the payment assessment process via the schedule of cost components. It covers the six categories of disallowed costs (unjustified costs, procedural breaches, post‑completion defect correction, non‑use of plant/materials, under‑utilised resources, and costs of preparing or conducting disputes), and illustrates how they are identified, recorded and potentially challenged by the Project Manager. The presenters stress the importance of open‑book auditability, robust record‑keeping, early‑warning compliance, clear scope definitions, and collaborative preparation of payment applications. Practical recommendations include pre‑contract briefings, aligning forecasts with the programme, using the schedule of cost components to map costs, and maintaining contemporaneous narratives to justify expenditures. The webinar concludes with a summary of best practices and a preview of the next episode on contractor value engineering.

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