Answers to the questions we hear most.

A remediator (or remediation company) is a specialist contractor engaged to physically remove mould, dry out water-damaged materials, and restore a property to a safe condition. They are not assessors. Their job is to do the work, not to determine the extent of the problem or verify that it has been resolved. That is the role of an independent assessor like MJ Building Bio.

An IEP is an Indoor Environmental Professional — someone qualified by knowledge, training, certification, or experience to assess the fungal and microbial ecology of a building, interpret laboratory results, and determine the condition of a property following water damage or mould contamination. Under AS-IICRC S520:2025, post-remediation verification should be carried out by an IEP with no connection to the remediator.

A Post-Remediation Verification (PRV) is an independent assessment carried out after remediation work is complete, to confirm that the property has been returned to a safe and acceptable condition before any rebuild or reinstatement begins. AS-IICRC S520:2025 requires that if the IEP performing the PRV is not independent from the remediator, this must be disclosed in writing to the client as a deviation from the standard.

AS-IICRC S500:2025 and AS-IICRC S520:2025 are official Australian Standards, published by Standards Australia in 2025, that govern how water damage restoration and mould remediation must be assessed, carried out, and verified in Australia.

Before 2025, Australia had no nationally recognised standard for these industries, which meant practices varied widely between contractors. The formal adoption of these standards now establishes a clear, legally recognised benchmark for the industry.

AS-IICRC S500:2025 covers professional water damage restoration. AS-IICRC S520:2025 covers professional mould remediation. All MJ Building Bio assessments are conducted in accordance with both standards.

These are the mould condition classifications used under AS-IICRC S520:2025.

Condition 1 — Normal fungal ecology. The indoor environment is consistent with a clean and dry space.

Condition 2 — Cross contamination. The indoor environment contains residual mould spores from a known Condition 3 source elsewhere in the same building.

Condition 3 — Actual mould growth. The indoor environment contains active, dormant, or hidden mould growth.

These classifications directly determine what remediation is required and what can be salvaged.

These categories classify the source and contamination level of water involved in a damage event.

Category 1 — Clean water from a sanitary source such as a burst water supply line or rainwater.

Category 2 — Grey water with some contamination such as a washing machine overflow or dishwasher leak.

Category 3 — Grossly contaminated water such as sewage, long-standing floodwater, or water that has passed through contaminated materials.

Building biology involves a comprehensive approach to assessing hazards in the built environment, with the understanding that homes and workplaces must support the health of their occupants rather than compromise it. Building biologists take a whole-building approach rather than a fragmented one — looking beyond the obvious to identify hidden issues that could affect not only the wellbeing of occupants but the longevity of the building itself.

Mould. It is one of the most common and most overlooked hazards in Australian homes, and one of the most significant contributors to unexplained illness. Mould does not always look like anything. It does not always smell. And standard checks frequently miss it. The consequences of undetected or inadequately remediated mould can be serious for your health, for your building, and for your finances.

Yes. Mould can produce allergens, irritants, and in some cases toxic substances known as mycotoxins. Long-term exposure can be harmful, particularly for people with respiratory conditions, allergies, or compromised immune systems.

Importantly, 75% of mould spores are non-viable (already dead) but may still contain mycotoxins which, if inhaled, can cause serious health effects. This is why killing mould with sprays or fogging is not a solution. Removal is.

Common symptoms associated with mould exposure include fatigue, headaches, respiratory issues, brain fog, joint pain, and skin sensitivity among many others. Most GPs are not yet well-equipped to identify mould-related illness, which is why many sufferers go undiagnosed for years.

Common signs include a musty odour you cannot locate, visible mould growth, water stains, and unexplained health symptoms affecting one or more household members. Mould problems can also be hidden behind walls, under floors, in roof cavities, or in ductwork. If you have had any water damage — even minor leaks that appeared to dry out on their own — mould may have established itself inside building cavities where it is not visible.

Not necessarily, and this is one of the most important things to understand before making any decisions.

AS-IICRC S520:2025 provides a clear framework for determining what needs to go and what can be cleaned or retained, based on the material's porosity and its condition classification. For example, a metal bed frame does not need to be discarded. A pillow does. Even in heavily contaminated homes, a proper assessment can save you from unnecessary expense.

It depends, but there are important things to understand first. Using bleach or fogging to kill mould does not remove it and does not address the health risk.

Small areas of mould on non-porous surfaces such as glass, sealed timber, or plastic can generally be cleaned safely with dishwashing liquid and a microfibre cloth. However, if the mould cannot be wiped off, if the area is larger than an A4 sheet of paper, or if anyone in the household is experiencing health symptoms, professional assessment and remediation is recommended.

For porous materials like plasterboard, professional replacement is required. Cleaning is not sufficient.

The cost depends on the size of the property and the scope of the assessment. Please contact Marijana directly for a quote based on your specific situation. The cost of an assessment is always a fraction of the cost of making the wrong decisions without one.

No. Fogging, misting, or spraying biocides does not remove mould and is not a recognised remediation method under AS-IICRC S520:2025, which states clearly that remediators should not mist or fog disinfectants in lieu of source removal.

Dead mould spores can still be allergenic, toxigenic, and harmful. The only solution is physical removal. If a company recommends fogging as their primary method, this is a significant red flag.

The findings of any assessment reflect who commissioned it. A remediator who also assesses the scope of their own work has a financial interest in the outcome. An independent assessor like MJ Building Bio has no relationship with any remediator, no interest in the scope of work being larger or smaller than it needs to be, and no reason to reach any particular conclusion. Independence is not just a selling point. Under AS-IICRC S520:2025, it is the expected standard.

Yes. Renters are often caught between a landlord who may be slow to act and uncertainty about what they are entitled to. An independent assessment gives you documented evidence of what is present in your rental property, what condition it is in, and what should be done about it.

For renters moving out of a mould-affected property, an assessment can help you understand which belongings are safe to take with you and which may need to be treated or replaced — saving you significant money and protecting you from bringing the problem into your new home.

Yes. MJ Building Bio provides independent assessments and post-remediation verifications for insurers and loss adjusters who require an objective, third-party opinion on the scope of damage or the quality of completed remediation work. All assessments reference AS-IICRC S500:2025 and AS-IICRC S520:2025. MJ Building Bio has no relationship with any remediator involved in a claim and no reason to reach any particular conclusion.

An assessment determines what is present, where it is, how extensive it is, and what needs to happen. It produces a report with findings and recommendations.

Remediation is the physical work of removing mould, drying materials, and restoring the property. This is carried out by a specialist contractor — not by MJ Building Bio. MJ Building Bio provides the assessment before remediation begins and post-remediation verification after it is complete, with no conflict of interest in the findings.

Do not panic, and do not start cleaning or discarding items before you understand what you are dealing with.

If you have water damage: Stop the source if possible. Notify your insurer. Contact MJ Building Bio before the insurer's assessor arrives so you have independent documentation from the start.

If you suspect mould without water damage: Note where you see or smell it. Avoid disturbing it. Contact MJ Building Bio for an assessment before taking any action.

Contact Marijana directly. There are no silly questions when it comes to your home and your health. Call 0472 536 856 or email info@mjbuildingbio.com.au.