Construction disputes have always been among the most complex forms of litigation. However, recent trends in New South Wales suggest that the landscape is changing. Increasingly, the outcome of construction litigation is being shaped not only by legal arguments and contractual interpretation, but by the quality, independence, and credibility of expert evidence.

From building defects and compliance issues to design failures and questions of causation, expert witnesses are playing an increasingly significant role in determining liability and quantifying loss. As a result, construction litigation is becoming more contingent on technical, expensive, and heavily dependent on expert opinion.

The Rise of Building Defect Litigation

Building defect claims continue to be a major source of construction litigation in New South Wales. Developers, builders, subcontractors, consultants and strata schemes are frequently involved in disputes concerning:

• Waterproofing failures;
• Structural cracking and movement;
• Fire safety deficiencies;
• Defective design;
• Non-compliance with the National Construction Code;
• Poor workmanship; and
• Inadequate supervision.

The increased regulatory focus on building quality has also contributed to greater scrutiny of construction practices. Parties are increasingly examining whether building work complies with statutory requirements, Australian Standards, and applicable building codes.

These claims often involve highly technical questions that cannot be resolved through factual or lay evidence alone. Determining whether a defect exists, how it occurred and who is responsible frequently requires specialised expert analysis.

Construction Litigation Is Becoming a War of Experts

In modern construction disputes, expert evidence is often the foundation upon which a case succeeds or fails.

Parties regularly engage experts from a range of disciplines, including:

• Structural engineering;
• Waterproofing consultancy;
• Building surveying;
• Fire safety engineering;
• Quantity surveying;
• Geotechnical engineering; and
• Building code compliance.

These experts are asked to provide opinions on matters such as causation, compliance, rectification methodology and the cost of remedial works.

In many cases, the central dispute is not whether a problem exists, but what caused it. A structural failure may be attributable to defective design, poor workmanship, unsuitable materials, inadequate supervision, or a combination of factors. Similarly, a waterproofing issue may stem from construction defects, design deficiencies, or maintenance failures.

The court is often required to assess competing expert opinions and determine which explanation is more persuasive. As a consequence, expert evidence has become one of the most influential aspects of construction litigation.

Building Code Compliance Under Greater Scrutiny

Recent years have seen heightened attention directed towards compliance with the National Construction Code and relevant Australian Standards.

Even where a building remains operational, allegations of non-compliance can expose project participants to substantial claims. Courts are increasingly asked to determine whether work complies with applicable standards and, if not, whether rectification is required.

Expert evidence is frequently relied upon to address questions such as:

• Whether non-compliance exists;
• The seriousness of the alleged defect;
• Whether the defect creates safety concerns;
• Appropriate rectification methods; and
• The likely cost of remedial works.

As regulatory expectations continue to evolve, compliance-related disputes are expected to remain a significant feature of construction litigation.

The Expert Witness Code of Conduct: Independence Is Critical

While expert evidence has become increasingly important, experts are not advocates for the parties who engage them.

In NSW, expert witnesses are subject to the Expert Witness Code of Conduct contained in Schedule 7 of the Uniform Civil Procedure Rules 2005 (NSW). The Code imposes a paramount duty on experts to assist the court impartially on matters relevant to their expertise.

This obligation overrides any duty owed to the party retaining the expert or paying their fees.

Experts are required to provide objective and independent opinions based on their specialised knowledge and experience. They must identify the facts and assumptions upon which their opinions are based and explain the reasoning supporting their conclusions.

Importantly, experts must not become advocates for the party who has engaged them.

The courts have consistently emphasised that the weight given to expert evidence depends not only on the expert’s qualifications but also on their independence and objectivity. Reports that appear partisan, selective, or argumentative may attract little weight. Conversely, reports that are transparent, balanced, and methodologically sound are likely to be regarded as more persuasive.

For legal practitioners and litigants alike, selecting an appropriately qualified expert is only part of the process. Equally important is ensuring that the expert understands and complies with their obligations under the Code.

Causation Remains a Key Battleground

One of the most difficult issues in construction litigation is establishing causation.

A defect may be readily observable, but identifying its source is often far more complicated. Courts must frequently determine whether loss resulted from design decisions, construction methods, material selection, supervision failures, or post-construction events.

Expert witnesses play a critical role in tracing the cause of defects and allocating responsibility among the various participants in a project.

As projects become larger and more technically sophisticated, disputes concerning causation are likely to become increasingly complex.

The Cost of Construction Litigation Is Rising

The growing reliance on expert evidence has significant cost implications.

Expert investigations, inspections, testing, and report preparation can be expensive. Complex disputes may require multiple experts across different disciplines, together with expert conferences, joint reports, and extensive cross-examination during hearings.

As a result, expert evidence often represents one of the largest components of litigation expenditure.

For parties involved in construction projects, early engagement of experts can assist in identifying issues, preserving evidence, and assessing the strengths and weaknesses of potential claims before costs escalate.

Looking Ahead

The increasing complexity of modern construction projects, coupled with heightened regulatory oversight and growing expectations regarding building quality, means that expert evidence will continue to play a central role in construction litigation.

However, success in construction disputes is not determined solely by technical expertise. Courts are increasingly concerned with the independence, objectivity, and reliability of expert witnesses. Compliance with the Expert Witness Code of Conduct is therefore as important as the substance of the opinion itself.

For developers, builders, consultants and strata schemes, the message is clear: construction litigation is no longer just a contest of legal arguments. It is increasingly a contest of expert evidence, where the most persuasive opinion is often the one that is both technically sound and demonstrably independent.