Expert Witnesses in Australian Residential Building Disputes

What it is

An expert witness in an Australian residential building dispute is an independent specialist briefed to give evidence on a technical issue. Typical roles include a building consultant on defect liability, a quantity surveyor on rectification cost, a hydraulic engineer on drainage, a structural engineer on movement and cracking, and a waterproofing specialist on wet area failures. The expert is briefed by one party but the duty is owed to the Tribunal, not the party paying the fee.

The code of conduct is the foundation

Every state tribunal that hears residential building disputes binds experts to a code of conduct or its practice note equivalent.

• NSW NCAT applies the Expert Witness Code of Conduct in Schedule 7 of the Uniform Civil Procedure Rules 2005 through Procedural Direction 3.
• Victoria VCAT applies Practice Note PNVCAT2 Expert Evidence.
• Queensland QCAT applies the Code of Conduct for Expert Witnesses in Annexure C to its expert evidence practice direction.

The codes converge on the same core duties. The expert must be independent. The expert must state opinions only within their area of expertise. The expert must set out the factual assumptions, the documents reviewed and the reasoning. The expert must distinguish between fact and opinion. The expert must update the report if a material new fact emerges before the hearing. The duty to the Tribunal is paramount and overrides any duty to the party paying the fee.

The structure of a useable report

A report that survives cross-examination has a predictable structure.

• A cover page with the expert name, qualifications, contact details and a code of conduct acknowledgement signed and dated.
• A scope of instruction extract quoting the brief letter.
• A list of documents and materials considered.
• A site inspection record with date, weather, attendees and method.
• Findings written defect by defect, each tied to the relevant clause of the NCC, the relevant Australian Standard and the contract scope.
• A scope of rectification for each defect with method and sequence.
• A cost section, either by the same expert if quantity surveying is in scope or by reference to a separately briefed quantity surveyor.

A report that omits the code acknowledgement, the assumptions section or the documents-considered list is liable to be excluded under any of the three tribunal regimes.

Concurrent evidence is the default

Australian tribunals routinely use concurrent expert evidence, sometimes called hot tubbing. Both experts give evidence at the same time. The tribunal member runs through each defect and asks each expert to comment. The lawyers ask short follow-up questions afterwards. NCAT and VCAT use it in most defect matters of more than a handful of items. QCAT uses it in larger matters.

Concurrent evidence works because it strips the partisan layer. The experts answer the same question in sequence and the tribunal can see who answers within their expertise and who reaches.

Joint conclave and joint report

Before the hearing the tribunal will often order a joint conclave. The experts meet without the lawyers. They produce a joint report listing each defect, the matters agreed and the matters in dispute, with reasons. The joint report is admissible. In Victoria the joint conclave is set out in PNVCAT2. In NSW Procedural Direction 3 supports a similar process. In Queensland the practice direction on expert evidence allows the tribunal to direct an experts conclave.

The joint report is often the single most important document at hearing. The matters in agreement disappear from the contest. The matters in dispute are framed precisely, with each expert position recorded in the experts own words.

Costs and quantum

A residential building defect file usually needs two cost layers. The building consultant gives a scope of rectification with method. A quantity surveyor takes that scope and converts it to a dollar figure. The QS rate should be priced at a reasonable market rate, not the highest quote available. Tribunal members discount obvious overpricing.

Builder duties

The builder must give the expert reasonable joint access to the site. The builder must not destroy or modify alleged defective work after a notice of defect is served. The builder must produce the contract file, variations and inspection records when the expert requests them through the proceeding.

Homeowner duties

The homeowner must give the expert reasonable joint access and produce photos, contemporaneous notes and prior inspection reports. The homeowner must not direct the expert to reach a predetermined conclusion. The expert who accepts that direction loses the report.

Common errors

Briefing an expert outside their field. Sending the expert to inspect alone without the other side. Failing to attach a code of conduct acknowledgement. Mixing opinion and advocacy in the same paragraph. Writing the report as a letter rather than a structured opinion. Omitting the documents-considered list. Pricing rectification at the highest market quote. Missing the joint conclave or sending the expert to conclave unprepared. Failing to update the report when a material new fact arises before hearing.