NEC4 is a family of contracts for construction, services and supply. Its principal works contract, the Engineering and Construction Contract (ECC), combines a common set of core clauses with selected options and documents prepared for the particular project.
The core clauses set out the parties’ responsibilities and the procedures they must follow. The options determine matters such as payment and liability, while the project documents describe the work and record the information needed to administer it. The resulting contract needs to be read as a whole, since a requirement in one part may depend on a provision elsewhere.
NEC4 contract types
The ECC is used for engineering and construction works. Other forms include the Professional Service Contract for consultancy appointments, the Term Service Contract for services provided over a period, and the Supply Contract for goods and associated services. NEC4 also has a separate Alliance Contract. Using the ECC does not, by itself, create an alliance arrangement.
There are corresponding subcontract forms and shorter contracts for more straightforward, lower-risk work, including the Engineering and Construction Short Contract. These share terminology and management principles with the wider family, but have their own provisions. A procedure used under one NEC contract should not be assumed to apply in the same way under another.
Ironbark Recycled Water Scheme
The Ironbark Recycled Water Scheme is a fictional regional Australian project that we will use for worked examples across this NEC4 series. A water utility is constructing a pipeline, pumping station and balancing tank to supply treated recycled water from an existing treatment plant to an industrial estate.
For the examples, the project uses NEC4 ECC Option C. The treatment plant remains in operation while the new works are constructed and connected. The Contractor therefore needs to coordinate its work with the operator, as well as install, test and commission the new system. A completed pipeline alone would not demonstrate that the scheme can deliver the required supply.
Later articles will return to Ironbark to develop its Scope and examine the Site Information. The project will also provide examples of submissions, early warnings and programme updates, followed by quality issues and assessments of cost, payment and compensation events. Using the same project will allow us to follow a problem through more than one process, rather than treating each procedure in isolation. Each article will contain the context needed to understand its example.
NEC4 ECC core clauses and options
The core clauses cover the Contractor’s responsibilities and the procedures for matters such as time, quality, payment and compensation events. They apply alongside one main option, which determines how the works are priced and paid for and how financial risk is allocated.
The other options deal with different subjects. W1 and W2 provide adjudication routes in different statutory contexts, while W3 uses a Dispute Avoidance Board. The dispute procedure is a separate choice from the main option. Ironbark’s use of Option C, for example, does not establish how its disputes will be resolved.
Secondary options add provisions for matters such as sectional Completion, delay damages, inflation and liability. They apply when selected, and some combinations are restricted. Relevant Y clauses may also be incorporated to address national legislation.
Additional conditions, commonly introduced through Option Z, can supplement or amend the standard provisions. They need to be read with the clauses they affect: a response period or entitlement in the published form may have been changed in the signed contract.
The ECC provisions described here are those of the June 2017 form incorporating the January 2023 amendments. Each project’s edition, selected options and amendments must be checked.
NEC4 ECC main options A to F
Options A and B are priced contracts, under which the Contractor generally carries the cost risk of delivering the priced work, subject to the adjustments allowed by the contract.
Option A uses an Activity Schedule containing lump sum prices for activities, with payment for the work based on completed activities or groups of activities. Option B uses a Bill of Quantities, with payment based on measured completed work at the relevant rates and lump sums. Measured quantities therefore affect payment under B, but neither option bases routine payment on the Contractor’s actual expenditure.
Options C and D are target contracts. C uses an Activity Schedule and D a Bill of Quantities to establish the target. During the works, payment is based on Defined Cost plus the Fee. Defined Cost is the cost assessed under the contract’s rules, rather than simply everything the Contractor has spent. The Fee is calculated using the agreed fee percentage.
The Contractor receives an agreed share of savings or bears an agreed share of excess cost against the adjusted target. That sharing assessment is separate from periodic payment. On Ironbark, completing an activity would not trigger payment as it would under Option A, and reaching the target would not, by itself, stop further payment. The team would need both cost records for payment and a record of adjustments to the target.
Option E also pays Defined Cost plus the Fee, but is a cost-reimbursable contract without the target-sharing mechanism found in C and D. The contractual cost controls still apply.
Option F is a management contract. The Contractor manages delivery through Subcontractors, apart from work identified in Contract Data for it to carry out itself. Its payment provisions address subcontract payments, its own priced work and the Fee. It should not be administered as though it were Option E.
NEC4 contract documents
The selected clauses provide the contractual framework. The project documents set out the work and the particulars needed to administer it.
Contract Data
Contract Data records the project particulars and identifies other contractual documents. Part one contains data provided by the Client and part two data provided by the Contractor. The required entries depend on the selected options and include named roles, dates, periods and commercial information.
It also identifies the Client’s Scope and, where applicable, Scope provided by the Contractor for its design. Accurate references and revisions are essential to establishing which requirements the parties have agreed.
Scope and Site Information
Scope specifies and describes the works and the constraints on how they are provided. For Ironbark, it would set out the required supply performance and commissioning requirements, together with restrictions on working alongside the operating treatment plant.
Site Information describes the Site and its surroundings. It may include surveys, ground investigation records and information about existing services. On Ironbark, an investigation report would describe what was found along the pipeline route. Scope would state what pipeline the Contractor has to provide. The distinction matters because information about existing conditions has a different contractual function from a requirement for the finished works.
Drawings, specifications, reports and models take their role from their content and how they are incorporated into the contract. A drawing may form part of Scope or Site Information; its filename or location in a shared folder does not decide its status. Scope may also be changed by an instruction under the contract.
The standard ECC does not impose a universal order of precedence across the documents. Ambiguities and inconsistencies must be dealt with under the contract, including any agreed amendments.
Pricing documents and cost schedules
The Activity Schedule serves Options A and C, and the Bill of Quantities serves B and D. Neither is Scope or Site Information. An item description in Ironbark’s Activity Schedule would not replace a requirement in Scope. E and F do not require either document as their standard pricing document.
The cost schedules have a separate purpose. A and B use the Short Schedule of Cost Components to assess Defined Cost, relevant to compensation events rather than routine payment for completed work. C, D and E use the Schedule of Cost Components, while F has its own provisions. These contractual rules may classify or assess costs differently from the Contractor’s accounts.
The Accepted Programme
The Accepted Programme is the programme identified in Contract Data or the latest programme accepted by the Project Manager. It records the planned sequence and timing of the work and is used in coordinating delivery and assessing the time consequences of change.
For Ironbark, the programme would show how construction, connections and commissioning are to be sequenced. A revised programme might show a later planned finish, but acceptance of the programme would not, by itself, move the contractual Completion Date or change Scope. A change to either requires the relevant contractual mechanism.
NEC4 contract roles
The Client commissions the works and performs the obligations allocated to it. The Contractor is responsible for providing the works in accordance with the contract.
The Project Manager administers the ECC, including issuing instructions, responding to submissions, assessing payment and dealing with compensation events. The Supervisor carries out the inspection, testing and Defect functions allocated to that role.
On Ironbark, the treatment plant operator would help plan the connections. A request from the operator would not automatically be an instruction to change Scope, however. That instruction would need to come from the Project Manager or an appropriately notified delegate. The same distinction applies to a technical discussion with the Supervisor: the team needs to know who has authority to make the decision.
