Construction Insurance – When Defects & Duration Disputes Arise

• Adroit Insurance and Risk
• - March 19, 2026

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You understand construction. You plan for delays, manage subcontractors, and navigate variations — that is the nature of the industry. What is less visible to most builders and developers is what happens in the insurance layer when a serious defect or project overrun occurs.

A construction project does not have one insurance policy. It typically has several, held by different parties, with different scopes, different triggers, and — critically — different commercial interests. Some insurers will look to recover costs from other parties on the project. Others will actively look for grounds to deny cover to a subcontractor or builder. And in a dispute about defects or duration, your adviser is managing all of that simultaneously.

Under a standard Contract Works policy, a defect itself — whether caused by poor design, substandard materials or inadequate workmanship — is not insured. The policy is not a workmanship guarantee. However, the damage that the defect causes to other non-defective parts of the structure is covered.

The scope of the defects exclusion is not uniform across all Contract Works policies. It is determined by which DE clause your adviser negotiated at placement. The three principal variants are: 

Clause	What is Excluded?	What is Covered?
DE3 (Limited Defective Condition)	The entire property or element that is in a defective condition.	Consequential loss or damage to other insured property free of the defect.
DE4 (Defective Part Exclusion)	Only the specific defective component or item — plus access costs to reach it.	Damage to all other parts of the structure, including those connected to the defective item.
DE5 (Design Improvement)	Only the betterment cost — the additional cost of improving beyond original specification.	Everything else, including full replacement cost of the defective part to its original spec.

Most standard market policies in Australia carry a DE4 clause. If your policy was placed without specific negotiation around the DE clause, you are almost certainly operating under DE4. Under a claim involving defective waterproofing, failed glazing or a structural element, the difference between DE3 and DE5 could represent hundreds of thousands of dollars in disputed coverage.

The practical reality of defect claims is that the boundary between a ‘defective part’ and ‘resultant damage’ is contested almost every time. Insurers apply the exclusion to its maximum extent. There are Definitional disputes over the scope of the ‘defective part’ — an insurer may argue the defective part is an entire system (e.g. all waterproofing) rather than a single membrane, substantially enlarging the exclusion. Workmanship versus damage, Documentation gaps and Multi-party responsibility — where a subcontractor’s defective work caused damage to the head contractor’s works.

A Contract Works policy does not simply run from commencement to practical completion. The policy typically covers a series of sequential policy periods:

• Construction period — from site commencement to practical completion.

• Testing and commissioning period — where relevant to the project type (particularly engineering and industrial projects).

• Maintenance or Defects Liability Period (DLP) — the period post-handover during which the contractor remains responsible for rectifying defects, typically 12 months.

Each period has defined start and end points. Disputes arise when those points are ambiguous — most commonly at the transition between construction and maintenance periods, and at the expiry of the policy’s maximum project duration.

Project overruns are normal. They result from permit and financing delays, materials availability, weather events, and disputes between stakeholders. What is not normal is for the insurance program to be updated to reflect those overruns. The most common failure point in construction insurance is that schedule changes are not communicated to the insurer — either because the insured does not realise the obligation exists, or because the adviser was not informed of the changed timeline.

Speak to your Risk Adviser before your next project commences — not after the first dispute arises.