Mould testing: when it is worth it, what it costs, who does it

An air sample test is one of the easiest lines to add to a mould quote and one of the hardest to interpret. Four Australian health departments have published a view on whether you need one, and their answer for visible mould is the same: generally not. Where testing does earn its fee is narrower, and knowing where that line sits saves the $250.

What the health departments say about testing

The reason is the same in every row. A test measures spores, and spores are everywhere, indoors and out. Without an Australian guideline value to compare a number against, a result cannot tell you whether a home is safe; it can only tell you there is mould, which you usually already knew.

When testing does earn its fee

The departments’ exceptions are specific, and they are all about not being able to see the problem:

• You can smell it but not find it. Mould inside a wall cavity, under a floor or in a ceiling space. NSW Health accepts contamination can sit in cavities or the ceiling, and points to an occupational hygienist where the source cannot be found.
• It keeps coming back. The Tasmanian department names mould returning despite prevention as a case for a hygienist.
• You need to know the extent before a job is scoped. WA’s 2015 guidelines treat contamination no greater than 1 m² as a simple job and larger areas as complex; an inspection that maps the extent is what decides which.
• A dispute needs evidence. A landlord, insurer or body corporate arguing about extent or cause. An inspection report can be part of that record, alongside a moisture map and photographs.

What mould testing costs

Compare the air test with what it is meant to inform. An inspection at $150–$350 that finds the moisture source is usually the more useful purchase, because the source is what decides the remediation. The mould removal guide covers the work itself.

Who does it, and what to ask

The health departments point to occupational hygienists. There is no licence to check: WA’s Department of Health guidelines say there are currently no formal Australian qualifications for certifying mould assessors (WA Department of Health, Guidelines for Managing Mould and Dampness Related Public Health Risks in Buildings), and a 2018 House of Representatives committee found limited legislative and regulatory guidelines for the testing and remediation industry (House of Representatives Standing Committee on Health, Aged Care and Sport, Report on the Inquiry into Biotoxin-related Illnesses in Australia (October 2018), para 2.4). So the questions to ask are practical ones:

1. What will you measure: surface, air, moisture, or all three?
2. What will you compare the result with, given there is no Australian guideline value?
3. Will the report identify the moisture source and the extent?
4. Are you also quoting for the removal? If so, ask for the inspection and the removal to be priced separately.

Home test kits and surface swabs. A settle plate or swab can show that mould spores are present, and the Tasmanian department’s point is that they are everywhere. That is exactly the reason it gives for not recommending tests. A kit can show that mould is present; it cannot show whether the level matters, because there is nothing to compare it with. A moisture meter and a torch find more.

Testing, insurance and rentals

For an insurance claim, the question is what made the building wet, not what species grew; mould cover and limits covers that. For a rental, the law in Victoria and Queensland speaks of mould and damp caused by the building or the property, not of spore counts; Melbourne and Brisbane set those rules out.

Common questions