When a tenant complains about mould, the right response is to acknowledge the complaint in writing, arrange an inspection without delay, identify the actual cause, fix it properly, and keep a clear record of every step. Getting that sequence right protects your tenant's health, satisfies your legal duties, and gives you a paper trail if the matter ever goes further.
Landlords who respond to a mould complaint with a quick repaint or a bottle of spray are making the most expensive mistake in property management. The mould returns within weeks, the tenant's complaint escalates, and there is now a documented history showing the landlord was aware of the problem and failed to fix it. This guide sets out the correct approach, step by step, and explains why the documentation matters as much as the work itself. This is general guidance, not legal advice - if you are dealing with a formal disrepair claim or enforcement notice, take proper advice on your specific situation.
Why responding correctly matters more than it used to
The legal landscape around tenant mould complaints has tightened significantly in recent years. Three overlapping laws already put the duty to investigate and fix mould firmly on the landlord in most cases: Section 11 of the Landlord and Tenant Act 1985, the Homes (Fitness for Human Habitation) Act 2018, and the Housing Health and Safety Rating System (HHSRS). The Renters' Rights Act 2025, now in force, has strengthened tenants' tools for enforcing those obligations, extending the Decent Homes Standard to the private rented sector and establishing a Private Rented Sector Ombudsman.
Awaab's Law - named after Awaab Ishak, the two-year-old who died following prolonged exposure to black mould in social housing - set strict fixed timescales for social landlords that came into effect from 27 October 2025. The government intends to extend similar requirements to private landlords under the Renters' Rights Act 2025. Our guide to Awaab's Law and mould for landlords covers the current timescales and what is coming for the private rented sector.
The direction of travel is clear. Treating a mould complaint as a low-priority issue - or worse, ignoring it - carries serious risk.
Step one - acknowledge the complaint in writing
The moment you receive a mould complaint - by text, email, phone call, or through a letting agent - respond in writing and confirm you will arrange an inspection. Do not commit to a cause or conclusion at this stage. Just acknowledge it and put a date on your response.
Why writing matters: if a complaint later goes to the council, the housing ombudsman, or court, the first question is when you knew about it and what you did. A text you sent verbally is not a record. A written reply with a date is. Emails are fine - a brief reply saying you have received the report and will arrange an inspection within a specific number of days is all you need.
Step two - inspect and identify the cause
Arrange an inspection promptly. When you visit, look beyond the visible mould - the growth on the surface is a symptom, not the problem. Your job at this stage is to find what is making that surface persistently damp.
- Check structural candidates first: the roof, gutters, window seals, external render, and any point where water could be entering from outside.
- Look at the plumbing: radiator valves, pipe joints under sinks, overflow connections, and if there is a flat above, any wet rooms directly above the affected area.
- Check ventilation: is there a working extractor fan in the bathroom and kitchen? Are trickle vents open and unblocked? Can moisture-laden air actually leave the property?
- Check the heating: are all radiators working? Is the property realistic to heat at a temperature that keeps wall surfaces above the dew point?
- Note the location and pattern: condensation mould appears at multiple cold spots - corners, behind furniture, around window reveals. Mould from a leak or structural damp concentrates at one point and spreads outward from there.
Our guide to what causes mould in a house explains the main causes - condensation, penetrating damp, rising damp, and hidden leaks - and what each one looks like. Getting the diagnosis right before committing to a fix saves time and avoids the frustration of treating the wrong problem.
Step three - fix the cause, not just the surface
Once you have identified the cause, fix it. This sounds obvious, but it is the step most landlords skip or delay - and it is what distinguishes a compliant response from one that creates a paper trail of failed repairs.
If the cause is a structural defect - a leaking roof, failed render, blocked gutter, broken heating system, or damaged window seal - repairing it is a legal obligation under Section 11 of the Landlord and Tenant Act 1985. You cannot pass this to the tenant through a clause in the tenancy agreement; the repairing duty cannot be contracted away.
If the cause is condensation from inadequate ventilation, improve the ventilation: install or repair an extractor fan, clear and open trickle vents, and consider a positive input ventilation unit for properties with persistent condensation across multiple rooms.
Then treat the mould properly. A professional-grade fungicidal wash applied with the correct dwell time kills mould at depth. A wipe with bleach lightens the staining but does not remove the underlying growth. A repaint without treatment is the worst outcome - it hides the problem temporarily and documents that the repair was cosmetic. See our guide to how to get rid of black mould on walls for good for the correct treatment method.
Step four - keep full records
Documentation is what separates a landlord who handled a mould complaint well from one who cannot demonstrate what they did. Keep a written record of every step.
- The date the complaint was received.
- The date you acknowledged it in writing.
- The date you inspected, with written notes of what you found.
- Any works instructed, with contractor details and completion dates.
- A follow-up check confirming the mould has been resolved.
- Photographs throughout - before, during, and after.
This record is your protection. If the complaint escalates to the council, the Private Rented Sector Ombudsman, or a disrepair claim, a clear timeline showing you investigated promptly and carried out proper works is the strongest position you can be in. A lack of records leaves you relying on memory against a written complaint.
Common mistakes that make mould complaints worse
These are the responses that landlords regret. They do not make the problem go away - they make it harder to defend later.
- Attributing the mould to tenant lifestyle without investigating. Councils and courts are sceptical of this. If the property has cold walls, no working extractor fans, or heating that tenants cannot practically afford to run at a temperature that prevents condensation, the property condition is the problem.
- Sending a cleaner rather than inspecting. Cleaning the surface is not a repair and does not discharge your legal obligation.
- Repainting over mould without treatment. This is the clearest possible evidence that you knew about the mould and chose to conceal rather than fix it.
- Delay. A complaint received in November that has not been properly investigated by January has generated several weeks of evidence showing inaction.
- Failing to keep records. Verbal assurances that work was done carry no weight if the complaint goes further.
When to call a professional
For any mould complaint involving a large affected area, recurring mould after previous treatment, any possibility of structural damp or a hidden leak, or where the property is subject to a formal complaint - professional involvement is the right call. A professional mould inspection includes damp meter readings at depth to identify whether moisture is structural or surface-level, a written summary of findings, and treatment with industrial-grade anti-fungal products under correct conditions.
That written report is what Awaab's Law requires social landlords to produce, and it is the same record that protects any landlord if a complaint escalates. It shows you investigated properly, found the cause, and fixed it.
We deal with tenant mould complaints for housing associations, councils, letting agents and private landlords across London and the South of England. We are Constructionline Gold accredited and fully insured, and have completed over 8,500 jobs. Every mould job includes a written findings and works summary and is backed by a 12-month guarantee - if the treated mould returns within the year, we come back and put it right. A photo on WhatsApp is the fastest way to get a quote. For the full picture of your legal duties when mould is reported, see a landlord's legal duties on mould in a rental property.
If you need a hand, Simpled Services can help. Call us on 020 4571 7367, message us on WhatsApp at the same number (020 4571 7367), or email hello@simpledservices.co.uk and we will take it from there.