Why Expert Evidence Can Fail If the Code Is Ignored in Building Disputes

Last Updated on 06/03/2026 by Damin Murdock

Building disputes often turn on expert evidence. However, even where an expert’s technical opinion appears sound, it may be excluded if it does not comply with the Tribunal’s procedural requirements. This issue was squarely illustrated in Tinsley v Masterton Homes Pty Ltd (Home Building) [2013] NSWCTTT 26.

What Happened

A homeowner engaged a residential builder to construct a single storey, four bedroom dwelling. Almost a year after the certificate of practical completion was issued, two alleged defects were identified:

• defects relating to the gutters
• defects relating to the roof tiles

The homeowner did not pursue the matter immediately. More than three years later, a claim was lodged in the Consumer, Trader and Tenancy Tribunal.

The Evidence Each Side Relied On

To support the claim, the homeowner relied on:

• an Independent Verification Body Services report to establish the existence of defects
• quotations to support the claimed cost of rectification

The builder defended the claim using:

• a report from a building consultant addressing the gutter defects
• a report from the Roofing Industry Association of NSW addressing the alleged tile defects

The Critical Problem

The Tribunal found that the Roofing Industry Association of NSW report did not comply with the Expert Witness Code of Conduct. In particular, the report failed to set out:

• the expert’s qualifications
• the expert’s experience
• other mandatory disclosures required when expert evidence is relied upon in Tribunal proceedings

Because of this non compliance, the Tribunal ruled that the report could not be relied upon as expert evidence.

The Consequence

Without admissible expert evidence on the roof tile issue, the builder was left unable to properly challenge the homeowner’s claim on that point. As a result, the builder could not mitigate the damages claimed and was significantly disadvantaged in the proceedings.

The outcome turned not on the substance of the expert’s opinion, but on a failure to comply with procedural requirements.

Why This Case Matters

This decision highlights a common but costly mistake in Tribunal proceedings. Expert evidence that does not comply with the Expert Witness Code of Conduct may be excluded entirely, regardless of its technical merit.

For self represented parties in particular, this can be decisive.

Practical Tips

If you are prosecuting or defending a building dispute in the Tribunal, especially without legal representation, it is essential to ensure that:

• every factual allegation in your claim or defence is supported by evidence
• allegations about defective or non defective work are supported by proper expert evidence, not opinion or assumption
• any expert report relied upon expressly confirms that the expert has read, understood, and complied with the Expert Witness Code of Conduct, with the Code attached to the report

Key Takeaway

Expert evidence that fails to comply with the Code may be worthless, no matter how persuasive it appears. Procedural compliance is not optional. It is often outcome determinative.

Feel free to contact Damin Murdock at Leo Lawyers via our website, on (02) 8201 0051 or at office@leolawyers.com.au. Further, if you liked this article, please subscribe to our newsletter via our Website, and subscribe to our YouTube, LinkedIn, Facebook and Instagram. If you liked this article or video, please also give us a favourable Google Review.

DISCLAIMER: This is not legal advice and is general information only. You should not rely upon the information contained in this article, and if you require specific legal advice, please contact us.