The short answer is to take it seriously, respond promptly and arrange a proper investigation. Ignoring a mould complaint or dismissing it as a lifestyle issue without evidence can lead to enforcement action, legal liability and reputational damage.
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Step one — respond and inspect
Acknowledge the complaint promptly and arrange an inspection of the property. Look at the affected areas, check the heating and ventilation provision, inspect accessible external defects such as gutters, pointing, render and window seals, and note the property's insulation and air-tightness. Do not assume the tenant is at fault without considering the building's contribution to the problem.
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Step two — identify the cause
Mould in rented properties can result from building defects, inadequate ventilation, insufficient insulation, heating problems, occupancy patterns or a combination. A fair assessment considers all these factors. Common building defects include failed extract fans, blocked air bricks, leaking gutters, poor insulation and cold bridges. Occupancy factors include moisture production from cooking, bathing and drying clothes indoors, but these should be weighed against the ventilation and heating provision available.
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Step three — take proportionate action
Address building defects and maintenance issues that are contributing to the problem. Improve ventilation where it is inadequate — repair or install extract fans, clear air bricks, consider PIV where suitable. Provide clear guidance to the tenant on managing moisture in the property. Document all actions taken with dates, photographs and records.
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When to call a specialist
If the cause is unclear, the problem is widespread, previous treatment has failed, or you need documented evidence for compliance purposes, a specialist inspection provides a balanced, evidence-based assessment that supports fair decision-making.
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Dan, Director / Surveyor
Last reviewed: July 2026. Advice is general until the property, access and visible evidence have been assessed.
When to arrange a visit
Book an inspection when the problem is persistent, changing, purchase-related or unclear after basic maintenance checks.