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The new NEC4 ECSC: Exploring new clause 83.4 for enhanced design liability

View profile for Derryn Rolfe
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The new NEC4 Engineering and Construction Subcontract (ECSC) is a widely used contract framework in the construction industry. Its clauses provide a structured approach to managing various aspects of a project. One such important addition in the NEC4 ECSC is clause 83.4, which addresses the contractor's design obligations and liability. But what are the details of the clause and what will be the implications for construction projects?

Understanding Clause 83.4

Clause 83.4 is applicable when the Contract Data specifies that the contractor's responsibility includes designing works using the skill and care typically employed by professionals handling similar projects. In such cases, the clause establishes the parameters for the contractor's liability for defects arising from their design work.

Liability for Design Defects

According to clause 83.4, the contractor cannot be held liable for a defect in their design unless they have failed to execute the design with the requisite skill and care, as would be expected of professionals working on similar projects. This clause sets a benchmark for design quality, ensuring that the contractor is responsible only for their failure to meet this standard.

Compensation for Correcting Defects

Should the contractor rectify a defect that falls outside their liability under the contract, it qualifies as a compensation event. In other words, if the contractor voluntarily corrects a defect for which they are not responsible, they are entitled to compensation as stipulated within the terms of the contract. This provision incentivizes the contractor to promptly address any design-related issues that may arise during the course of the project, even if they are not directly liable for them.

Insurance Coverage

To further protect against potential claims arising from the contractor's failure to meet the required design standards, clause 83.4 mandates that the contractor provides insurance coverage. This insurance covers claims made against the contractor resulting from their failure to use the skill and care typically employed by professionals working on similar projects. The Contract Data will specify the minimum amount of insurance coverage required.

The insurance coverage starts from the project's commencement date and remains in effect until the period stated in the Contract Data expires. This provision ensures that any claims arising from design-related issues during the project's lifespan are adequately covered, mitigating potential financial risks for both the contractor and the client.

Implications and Benefits

The introduction of clause 83.4 in NEC4 ECSC brings several important benefits to construction projects:

  • Clear Design Liability: By establishing a standard of skill and care expected from professionals in similar projects, the clause provides clarity regarding the contractor's liability for design defects. This helps manage expectations and responsibilities between the parties involved.
  • Incentivized Proactive Action: The compensation event provision encourages contractors to proactively address defects, even if they are not directly liable for them. This fosters a collaborative environment and promotes timely resolution of design-related issues.
  • Enhanced Risk Management: The insurance requirement outlined in clause 83.4 ensures that potential claims arising from the contractor's design failures are adequately covered. This helps manage financial risks associated with design-related disputes and provides peace of mind for both parties involved.


Clause 83.4 in NEC4 ECSC strengthens the design liability framework within construction projects. By establishing a benchmark for design quality, incentivizing proactive action, and requiring insurance coverage, this clause promotes transparency, risk mitigation, and collaborative problem-solving. Construction projects benefit from clearer expectations, more efficient issue resolution, and improved financial protection, resulting in a more successful and harmonious project delivery.

If you have any questions, our Construction and Engineering team will be happy to help. Please get in touch for further information.