I’ve had a letter published in Building and Environment (Elsevier) responding to Coulburn et al. (2026), a paper arguing that Australia’s mould assessment and remediation sector is “unregulated” and “failing,” with a widely quoted claim that only 5% of insurance-managed homes passed pre-occupancy clearance testing.

These are the kinds of statistics that end up in litigation, regulatory submissions and media headlines — so they deserve close scrutiny. My letter raises four concerns:

  • The sample. The findings rest on interviews with 18 practitioners recruited from inquiry submissions and building-biology networks — a group skewed toward disputes and failures, and not required to meet the IEP standards set out in AS-IICRC S500 and S520. Insurers, loss adjusters and major restorers were excluded.
  • The “5% pass rate.” This headline figure doesn’t come from the interviews at all. It’s imported from a single proprietary dataset, judged against self-authored guidelines published in lower-rigour venues — a risk of a closed evidentiary loop rather than a validated sector-wide finding.
  • The international picture. The paper casts Australia as uniquely unregulated. In practice, the US and UK also rely largely on consensus standards and general housing law rather than mould-specific statute — and Australia’s adoption of AS-IICRC S500/S520 aligns it with international practice.
  • Process vs. technical failure. The paper leans on the 2022 flood inquiry, which examined insurer service failures (delays, communication), and risks conflating those with technical failures in remediation.

The problems of dampness and mould in Australian housing are real and pressing — Coulburn et al. are right to raise them. But if a paper is going to shape policy and legal debate, its strongest claims need to be interpreted with appropriate caution.

Read the letter: Law, T. (2026). Reassessing evidence and policy claims in Coulburn et al. (2026) on mould, insurance and regulation. Building and Environment, 303, 114865. https://doi.org/10.1016/j.buildenv.2026.114865