Abstract

Mould-related litigation in Australian rental properties has increased by 250% over the past decade, fundamentally transforming expert witness practice and civil dispute resolution at the intersection of rental law, indoor air quality science, and public health and building science. This paper updates the author’s 2018 analysis, presenting the first comprehensive longitudinal study of Victorian Civil and Administrative Tribunal (VCAT) mould jurisprudence through analysis of 406 published decisions spanning 27 years (1998-2025). The dataset documents annual case volumes rising from 6-7 cases (1998-2013) to over 30 cases by 2025, with quadratic trend modeling (R²=0.611) indicating sustained structural growth. However, these 406 determinations represent only a lower-bound indicator of dispute prevalence, as many matters resolve through negotiation, consent outcomes, alternative dispute resolution, or withdrawal without generating published decisions. Victoria’s 2021 Residential Tenancies Regulations introduced Australia’s first explicit requirement that rental properties be “free from mould and dampness caused by or related to the building structure,” creating unprecedented regulatory clarity that coincided with robust health evidence demonstrating 30-50% increased respiratory risks from dampness exposures. Comparative jurisdictional analysis reveals that while Queensland has adopted similar explicit standards, most other Australian states and territories rely on general habitability provisions, lacking Victoria’s causation-focused evidentiary framework. VCAT case analysis demonstrates the tribunal’s increasing sophistication in evaluating competing expert evidence, demanding quantitative data rather than mere visual observation for causation analysis, moisture measurement, and remediation assessment. The tribunal has progressively rejected dubious methods such as standalone fogging, establishing evidencebased decision-making that provide critical operational guidance for mould inspectors and assessors in collecting quantitative environmental data, documenting moisture pathways, and applying professional remediation protocols aligned with international standards for cleaning/remediation and source removal expectations. For renters contemplating proceedings, VCAT jurisprudence demonstrates that favorable outcomes turn less on the mere presence of visible mould and more on quality evidence linking the moisture sources, building defects, and remediation adequacy to the mould and in turn to loss of amenity or health risk. These findings establish an evidence-based framework for mould inspectors, assessors, remediators, expert witnesses, legal practitioners, affected occupants, and policymakers navigating the evolving regulatory landscape for mould disputes across Australian jurisdictions.

Keywords

mould, building disputes, VCAT, indoor air quality, health impacts, expert witness, building science, moisture management, residential tenancies, regulatory framework, Australian jurisdictions, fogging, remediation