Mould assessment, testing and health questions

Mould can affect health, but colour alone does not establish the risk.

Mould exposure may irritate the nose and airways, with symptoms such as sneezing, coughing or wheezing. People with allergies, asthma, other lung conditions or weakened immunity may be more affected. Colour alone does not identify the species or establish the health risk. Visible growth and persistent dampness deserve attention whether the mould is black, white or another colour.

A building assessment cannot establish that mould caused an individual person’s symptoms. Speak with a health professional about symptoms, asthma, pregnancy, a baby or weakened immunity, and discuss precautions before cleanup. Avoid assigning a medical meaning to an air-test number or a completion photograph. Seek urgent medical help for severe breathing difficulty rather than waiting for a property report.

Sources: HealthEd - mould after flooding (opens in a new tab); CDC/NIOSH - damp buildings and health (supplementary guidance) (opens in a new tab); CDC/NIOSH - mould testing and remediation (supplementary guidance) (opens in a new tab).

A useful assessment records visible growth and damage, musty odours, moisture patterns, access limits and likely next steps. A musty smell without visible mould may justify checking adjoining spaces, leaks, ventilation and wet materials. Findings should distinguish what was observed from assumptions and the occupant’s account.

A thermal camera shows surface temperature differences, not mould or a view through walls. Moisture measurements and the building history can help interpret a pattern, but they do not prove a hidden leak or growth by themselves. Opening up or further specialist investigation may be needed; obtain owner approval, consider services and hazardous materials, and agree the cost before disturbing a lining.

Sources: CDC/NIOSH - mould testing and remediation (supplementary guidance) (opens in a new tab); FLIR - thermal imaging and water leaks (manufacturer explanation) (opens in a new tab).

The methods answer different questions about the material or air sampled.

You can request mould testing without explaining your private reason. We help record separate sample locations and explain what the laboratory findings cover. Surface testing answers questions about the submitted material; a building assessment considers moisture, affected materials and repair work. Air samples are a snapshot; swabs describe the sampled surface. A negative sample does not prove that all hidden spaces are clear, and routine spore counts are not a medical clearance.

Home culture kits can grow fungi already common in the environment and do not establish the extent or cause of a building problem. ERMI was developed as a research tool; the US EPA does not recommend it for routine public use. For any method, understand how sample locations are recorded and what the findings cover. If a report recipient requires a particular collection method or format, check that before sampling; you do not need to disclose your private reasons.

Sources: CDC/NIOSH - mould testing and remediation (supplementary guidance) (opens in a new tab); US EPA - limits of ERMI (opens in a new tab).

Before buying, allow time for a building assessment, any moisture investigation and a written repair scope before the relevant contract deadline. A mould-focused assessment is not automatically a complete pre-purchase inspection. For selling, keep the repair history and relevant records and seek advice about accurate disclosure of known issues.

A report can document observations, photographs, limitations and proposed repairs for a landlord, insurer or dispute. It does not guarantee acceptance by a Tribunal or insurer, certify the entire building or establish medical safety. Agree who receives it and who authorises sharing. Use the private enquiry form for property information, avoid including unrelated personal details in photos and read our privacy information before sending files.

Sources: Tenancy Services - mould and dampness (opens in a new tab).

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