One of the hardest situations for a landlord is a tenant reporting mould while you believe the cause is how the home is used: clothes drying on radiators, windows never opened, the heating off. The tenant may say the property is defective. You may both be partly right. This guide sets out a fair process for these cases: what the law expects of you, how to investigate the cause properly, how to gather evidence that stands up, and how to talk to the tenant without the dispute escalating.
Key takeaways
- Act on every report, even if you suspect lifestyle. Delay is the most common reason landlords lose these cases.
- Rule out building causes first: leaks, failed extraction, missing insulation, cold bridging, inadequate heating.
- Use objective evidence, such as humidity loggers, dated photos and an independent survey, rather than opinion.
- Give practical help, not just advice: working fans, a place to dry clothes, affordable heating.
- The government’s damp and mould guidance warns landlords not to blame “lifestyle” without investigating.
What the law expects
You must keep the structure and installations in repair and make sure the home is fit to live in throughout the tenancy. Damp and mould growth is one of the hazards councils assess. Tenant behaviour can be relevant, but it does not remove your duty to investigate, and if the property makes condensation likely, for example because there is no extractor fan or the walls are uninsulated, the problem is still yours to fix.
The government’s guidance Understanding and addressing the health risks of damp and mould in the home tells landlords to respond sensitively and not to assume lifestyle is the cause. Awaab’s Law already sets deadlines for social landlords, and the government is consulting on applying it to private rentals from 2027 at the earliest. For the full legal picture, see our guide to landlord responsibilities for damp and mould.
Step 1: Respond quickly and neutrally
Acknowledge the report in writing the same day. Thank the tenant, ask for photos and where the mould is, and book a visit. Do not mention lifestyle at this stage. A first reply that blames the tenant is often quoted back in complaints and court claims.
Step 2: Investigate the building first
Check the building
- Leaks: roof, gutters, pipes, shower seals
- Extractor fans: present, working, enough flow
- Trickle vents and window seals
- Insulation in the loft and walls
- Cold spots: lintels, corners, behind wardrobes
- Heating: works, is controllable, affordable to run
Then look at usage
- Clothes dried indoors without ventilation
- Vents taped over, fans switched off
- Heating rarely used
- Furniture pushed against cold outside walls
- More occupants than the home is designed for
If both columns apply, fix the building issues first. That is what a council or court will look at first.
Mould in one patch on an outside wall that grows after rain points to penetrating damp. Mould in corners, behind furniture and around windows in several rooms points to condensation. A tide mark at the base of walls may be rising damp or bridging. A damp meter helps record readings, but it does not diagnose the cause on its own.
Step 3: Gather objective evidence
| Evidence | Why it helps |
|---|---|
| Dated photos of every affected area, at each visit | Shows extent and whether it is improving or worsening |
| Humidity and temperature loggers left for 2 to 4 weeks | Shows real conditions: persistent high humidity with low temperatures points to condensation |
| Fan flow test or electrician’s report | Proves extraction works, or shows it needs upgrading |
| Independent surveyor’s report | An impartial diagnosis, more persuasive than a damp-proofing salesperson |
| A log of every report, visit, letter and repair | Shows you acted promptly and reasonably |
The Property Inspection Kit includes a damp and mould section in its room-by-room forms, so each visit is recorded the same way.
Step 4: Fix what is yours to fix
Treat the existing mould with a fungicidal wash and repair any defects. Then improve the property’s ability to cope with normal life: humidistat extractor fans, positive input ventilation in houses with persistent condensation, insulation, and heating that tenants can afford to run. These measures work regardless of tenant habits, which makes them the strongest answer to a dispute.
Step 5: Talk to the tenant about usage, helpfully
Once you have checked the building, write to the tenant with what you found, what you have done, and practical suggestions. Keep the tone supportive:
- use the extractor fans when cooking and showering, and keep them running for a while after;
- keep trickle vents open and furniture slightly away from outside walls;
- dry clothes outside or in a ventilated room with the door closed and the window open;
- keep a low, steady heat in cold weather rather than short bursts;
- wipe condensation from windows each morning.
Make it easier to do the right thing: a rotary washing line, a tumble dryer or a dehumidifier can resolve a dispute quickly. See our guide to the best dehumidifiers for rental properties. If cost of living is the issue, point tenants to energy support schemes rather than suggesting they simply heat more.
Step 6: Follow up and review
Return after 4 to 6 weeks, take photos and readings, and record the result. If the mould has returned despite your improvements and clear usage advice, a second independent assessment is the best way to settle where responsibility lies. Keep the whole file. If the tenant complains to the council, you will be able to show what you did and when.
Mistakes that weaken your position
- Replying “it’s condensation, open a window” without visiting.
- Painting over mould without addressing the cause.
- Ignoring a vulnerable household: babies, older people, or people with respiratory conditions need faster action.
- No written record of reports, visits and advice.
- Threatening to end the tenancy over a repair complaint. Councils treat this seriously, and you would need a valid Section 8 ground anyway.
Written by The Landlords Portal Team and checked against GOV.UK guidance in November 2026. Applies to private rented homes in England. This is general information, not legal or surveying advice.
Frequently asked questions
Is mould the tenant’s fault if they dry clothes indoors?
It can contribute, but you must still check that the property has adequate ventilation, insulation and heating. If the home cannot cope with normal living, the problem is yours to fix.
How can I prove damp is caused by condensation?
Humidity and temperature loggers over several weeks, dated photos showing the pattern of mould, and an independent surveyor’s report are the most persuasive evidence.
Can I charge the tenant for mould damage?
Only from the deposit at the end of the tenancy, and only where you can show the tenant caused damage beyond fair wear and tear. Adjudicators will ask whether the property itself contributed.
Template pack from Landlords Portal
Run every inspection properly: the Property Inspection Kit
Dated evidence of the property's condition protects you in repair, damp and deposit disputes. This kit gives you every document for an inspection, written for landlords in England.
- 24-hour notice letter and tenant repair report form
- Room-by-room checklist, inspection report and photo log
- Follow-up letters, plus an Excel tracker for gas safety, EICR and EPC dates
