An NEC contract structure works like a set of building blocks: core clauses that apply to every job, a main Option for how the Contractor is paid, a dispute Option, any secondary Options and the job's own details. Together they make one contract, so you need to read each part alongside the others, not just the printed core clauses.
This guide covers the NEC4 Engineering and Construction Contract (ECC). Other NEC forms use a similar approach, though short contracts are simpler and are numbered differently. For an introduction to NEC, see the comparisons section.
The parts of an NEC4 ECC
| Part | What it does | Who decides what goes in it |
|---|---|---|
| Core clauses | Sections 1 to 9: the rules common to every ECC | Fixed by the form |
| Main Option | One of A to F, setting the pricing mechanism | Client, one Option only |
| Dispute Option | One of W1, W2 or W3, depending on the law and approach | Client |
| Secondary Options | X and Y(UK) clauses that add topics such as delay damages or a bond | Client, choosing the ones it needs |
| Z clauses | Additional conditions written for this contract | Client, and sometimes negotiated |
| Schedule of Cost Components | Defines what counts as Defined Cost | Fixed by the form, with its own rates and percentages from the Contract Data |
| Contract Data | Part one from the Client and part two from the Contractor: names, dates, periods, rates | Both Parties, each its own part |
| Scope | Describes what's to be provided and any constraints | Client, plus any Contractor proposals that are included |
| Site Information | Describes the Site and its surroundings | Client |
| Pricing document | An Activity Schedule (Options A, C) or a Bill of Quantities (Options B, D) | Contractor |
| First programme | Identified in the Contract Data, or submitted after the contract starts | Contractor |
In NEC3, the Scope is called Works Information and the Client is the Employer, while the arrangement is otherwise broadly the same.
How one question moves through the parts
Take a fictional question from a site team: "Do we have to pay delay damages, and how much?" You'd go through these steps:
- The secondary Options. Is X7 selected in the Contract Data? If not, there's no delay damages clause, even if everyone assumes otherwise.
- The Option's own clauses. The X7 clauses set out how the damages work.
- The Contract Data. That's where you'll find the rate per day and any sections.
- The core clauses. Clause 30 and the definitions tell you what Completion and the Completion Date are.
- Any Z clauses. These might cap the amount or change how the Option works.
- The compensation event history. Implemented events may have moved the Completion Date from the date you started with.
A single answer can draw on five parts. This is why reading one clause in isolation can lead you astray.
What if the parts conflict?
The NEC4 ECC doesn't have the kind of order-of-precedence clause people often expect. If either the Project Manager or the Contractor spots a conflict or an unclear point across the documents, it notifies the other, and the Project Manager then instructs how it is to be resolved (17.1). Whether a compensation event follows depends on the circumstances and the assumptions in the contract, so check this if you run into it.
A client's amendments might add a precedence clause, and if there is one, it's normally in the Z clauses. Check there as well.
What people get wrong
- Assuming a secondary Option applies. Retention, delay damages and bonds only apply where they're selected.
- Leaving out the main Option clauses. A copy of the core clauses alone doesn't tell you how you're paid. The main Option clauses often contain vital definitions, including what Prices means.
- Treating the Contract Data as a form to fill in. It sets periods such as the period for reply and programme intervals, and those decide your deadlines.
- Burying obligations in the Scope. Payment terms or risk transfers placed in a specification can clash with the conditions. Put each thing in the right place.
- Ignoring the short forms. They have different structures. The ECC vs ECSC comparison shows some of these differences.
A contract file checklist
Before you start work on an NEC job, check that your contract file has all of the following in the agreed versions:
- The core clauses, the selected main Option, dispute Option and secondary Option clauses, including their amendment date
- Contract Data parts one and two, completed and agreed
- Z clauses, or confirmation that none apply
- Scope and Site Information, with every document and revision listed
- The Activity Schedule or Bill of Quantities
- The programme identified in the Contract Data, if one is
- The form of agreement or award letter, and anything else that's stated to form part of the contract
Related guides
- NEC vs Other Construction Contracts
- NEC Core Clauses Explained
- NEC ECC Contract Overview
- What Does NEC Stand For?
- NEC Contracts Explained for Beginners
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This guide is general information in our own words, not legal advice. Your contract and its Contract Data always govern. NEC, NEC3 and NEC4 are trade marks of Thomas Telford Ltd; Contract Status is not affiliated with or endorsed by NEC.