Disallowed Costs In NEC4 Cost Contracts Explained

5 May 2026 · 60 min
1:00:10

This NEC4 webinar (Episode 9) hosted by Glenn Hyde and featuring Ben Walker (Gather) and David Allen (SECA Southern) explains the concept of disallowed costs in the cost‑reimbursable NEC4 options (C, D, E and, briefly, F). The presenters define disallowed costs, show why they are needed, and walk through each of the six contractual bullet‑points that trigger a cost to be disallowed. They describe how disallowed costs interact with the definition of defined cost, the payment‑assessment process (Clauses 50.1, 50.3, 51.1) and the project manager’s certification role. Practical guidance is given on record‑keeping, subcontractor and procurement procedures, early‑warning and dispute preparation, wastage/under‑utilisation of plant, materials and resources, and defect correction after completion. The session stresses collaborative preparation of payment applications, early‑warning use, clear pre‑contract scope definition and ongoing communication with the project manager to minimise the risk of costs being disallowed. The presenters also answer audience questions and preview the next webinar on contractor value engineering.

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