I remember a Project Manager on a flagship UK project telling me: "NEC does not require CPM." 

The deeper consequence of that mindset aside, it got me thinking. Does it, or does it not?

Technically, the acronym "CPM" (Critical Path Method) appears nowhere in the core clauses. But the contract’s logic effectively mandates it. If you aren't using CPM, you aren't following the contract.

Here is why the "hidden" logic of NEC makes CPM essential:

 

• Clause 15: You must notify events that risk delaying Completion or Key Dates. Without a logic-linked programme showing where float exists and what is critical, that notification is guesswork.

• Clause 31.2: The programme must show both Completion and planned Completion - two distinct dates that only function as separate points on the timeline through an end-to-end logic network.

• It explicitly demands you show "float" and although NEC refers to "float" generally, practitioners know that NEC recognizes different types of float by implication. You cannot mathematically generate free float, total float and terminal float without CPM logic. 

• It also mentions “order and timing of the work”. "Order" is a synonym for Network Logic (Predecessors/Successors). You cannot demonstrate the "order" of 2,000 activities in a dynamic environment without a CPM relationship web.

• Clause 31.3: The Project Manager can reject a programme that is not realistic, not practicable, does not show the information the contract requires or does not comply with the Scope. A realistic and practicable timeline derived without CPM methodology is difficult to defend, and the Scope almost usually prescribes CPM tools (such as P6 or Asta Powerproject) and project controls processes aligned with CPM on top of those listed in core clauses of the contract.

• Clause 32: The Contractor must show the effect of progress on remaining work that pushes uncompleted work into the future. Without CPM, "showing the effect" is just drawing a new line, which fails the "realistic and practicable" test of Cl 31.3. Demonstrating forward effect requires a dynamic model. That is CPM.

• Clause 62.2: This is the most direct requirement for a "reprogrammed" logic network. It states that when submitting a quotation, if the programme for remaining work is altered by the event, the Contractor must include those alterations to the Accepted Programme. You cannot reliably "alter" a programme and show the resulting delay to the Completion Date without a CPM engine. Not to the standard required by Cl31.2.

• Clause 63.1: Demands progress measurement and reforecasting of the Defined Cost of the work not done by the dividing date and the resulting fee - in other words you are required to model how a Compensation Event ripples through the network.

• Clause 63.5: Delay to the Completion Date is assessed as the length of time that planned Completion moves due to the compensation event. This is how NEC protects terminal float. Without CPM, you cannot isolate how an event shifted planned Completion relative to the Completion Date.

• Clause 64.1: This clause allows the Project Manager to make their own assessment of a Compensation Event. If the PM uses a CPM model to assess a delay (which they almost certainly will) and the Contractor has only provided a flat list of dates, the Contractor has effectively forfeited their right to argue the logic.

So when a PM tells you NEC doesn't require CPM, they're technically right. But they're missing that the contract's own logic already assumes it. 

The method is not precisely named, but it’s embedded, and because of that it’s more than likely that the Scope further defines how you maintain a CPM schedule including what tools to use.

* I did considered Clause 36.1 (Acceleration), but NEC defines acceleration as bringing the Completion Date forward, not just "working faster" as a scheduler might define it.

 

 

Best, Radek Makar Director | ViViAD radek@viviad.co.uk

ViViAD is an independent consultancy specialising in Planning, Project Controls, Power BI Reporting, and Construction Claims Support. We work across the UK - typically on NEC contracts in defence, nuclear, renewables, and infrastructure - embedding with project teams to bring structure, clarity, and commercial control. Interim or longer-term, we fit around what you need.