Damp and mould has become one of those topics where everyone immediately starts the blame game.
Some landlords say, “It’s tenant lifestyle.”
Some tenants say, “It’s the landlord’s fault.”
The truth, as usual, is more nuanced: damp and mould can be caused by the property, the way the property is used, overcrowding, poor ventilation, inadequate heating, leaks, defective gutters, cold walls, or a messy combination of all of the above.
And now, with councils able to issue fines of up to £7,000 from 22 June 2026 for serious Category 1 hazards in rented homes, landlords cannot afford to deal with damp and mould by guessing, arguing or hoping it disappears when the weather improves. The new penalty applies to serious hazards including severe damp and mould, excess cold, faulty electrics, fire hazards, structural issues and unsafe layouts.
We have heard that council inspectors are being encouraged to issue on-the-spot fines in addition to enforcement notices.
See also: The Housing Health and Safety Rating System (England) (Amendment) Regulations 2026 and Housing Health and Safety Rating System (HHSRS) guidance
Tenant lifestyle is real but so is landlord responsibility.
Let’s be honest. Tenant behaviour can absolutely contribute to condensation and mould.
Drying clothes indoors. Not using extractor fans. Blocking vents. Keeping windows shut. Not ventilating every day, even if only for a short while regardless of the temperature outside. In Germany, they have a whole word for it: Lüften. It means opening windows properly for a short burst to change the air. The Scandinavians do versions of it too. In Sweden, it’s vädra. In Norway, lufte. In Britain, we often call it “freezing the house”, then wonder why the bedroom walls and windows have things growing on it. Pushing wardrobes hard against cold external walls. Heating the property inconsistently because energy bills are painful. Having more people living in a property than it was designed for. All of that increases moisture.
Government guidance recognises that condensation is one of the most common causes of damp and mould, and that everyday activities such as showering, drying laundry and cooking add moisture to the air. It also recognises that high humidity can be linked to overcrowding, particularly in HMOs or small temporary accommodation.
So no, landlords are not automatically guilty every time there is mould.
But tenants are not automatically to blame either.
That is the bit some people still struggle with. Government guidance says landlords should not treat tenant management of condensation as a substitute for assessing and addressing the underlying issue. It also says landlords should work with tenants where small, reasonable behaviour changes may help, but this must sit alongside tackling root causes such as building defects, poor ventilation, inadequate heating or low indoor temperatures.
In plain English: it can be tenant behaviour, but you need evidence. It can be the property, but you need evidence. It can be both, but the council will not care and will have powers to issue heavy fines.
The new £7,000 fine is not for every bathroom black spot
This is important.
Councils are not supposed to hand out £7,000 fines because someone found a small patch of mildew on the silicone behind the shampoo bottles.
The new power is aimed at serious Category 1 hazards. These are the most dangerous level under the Housing Health and Safety Rating System, known as HHSRS. HHSRS is the system councils use to assess health and safety hazards in homes, and the updated 2026 framework now covers 21 hazards.
Councils already had enforcement tools where they could require repairs, carry out emergency works and recover costs. The difference now is that another financial penalty route has been added, making serious disrepair harder to ignore (and, cough, an extra income stream for councils, cough).
So good landlords should not panic. But they should tighten up.
The Renters’ Rights Act changes things
The Renters’ Rights Act tenancy reforms started on 1 May 2026, and the government described them as major changes to renting in England. Section 21 “no-fault” evictions are no longer available for existing and new tenancies from that date.
That matters because tenants are now more likely to report issues they may previously have kept quiet about. Some will report genuine problems. Some may exaggerate. Some may misunderstand condensation. Some may only report it after it has become much worse.
The practical answer is not to become defensive. The answer is to become organised, proactive and act quickly.
The real issue is proof
If a landlord believes damp and mould is caused by tenant behaviour, overcrowding or misuse of the property, they need to prove it properly.
That means inspection notes, dated photos, moisture readings, extractor fan checks, heating checks, ventilation checks, evidence of blocked vents, evidence of clothes drying without ventilation, occupancy concerns, tenancy records, contractor reports, and written advice given to tenants.
A message saying “please open the windows” is not a damp investigation.
Equally, if there is a leaking gutter, cracked render, defective roof tile, poorly sealed bath, broken or clogged extractor fan, undersized heating system or cold wall with no practical ventilation, the landlord needs to deal with it.
What good landlords should do now
When damp or mould is reported, inspect quickly. Do not diagnose from a photo unless the photo is of water pouring through the ceiling.
Check the basics: leaks, roof, gutters, downpipes, pointing, windows, seals, heating, extractor fans, trickle vents, insulation, cold spots and occupancy. Then look at how the property is being used. Are clothes being dried indoors? Are fans switched off? Are rooms overcrowded? Are vents blocked? Are tenants struggling to heat the property?
What tenants need to understand too
Tenants also have a part to play.
Use extractor fans. Ventilate after showers and cooking. Do not block vents. Keep furniture slightly away from cold external walls where possible. Report leaks and mould early. Do not wait until things are really bad before reporting it.
And overcrowding is not a small issue. More people means more breathing, more showers, more cooking, more laundry and more moisture. In HMOs especially, the margin for error is smaller. If a room is being used beyond what it was intended or licensed for, damp and mould risk can increase quickly. For single lets together with the increasing cost of living and poor job prospects, expect more tenants to live in properties too small for their needs and adult children staying home for longer. This needs to be managed carefully and sensitively.
The Sentinel view
We will not assume blame either way.
We will investigate, record, advise and act.
Damp and mould is a property management issue, a health issue and now a compliance issue. Compliance is what we are good at and have an excellent reputation for by different local authorities.
The landlords who should be worried are the ones who ignore reports, delay repairs, fail to inspect properly, refuse to maintain or upgrade heating and ventilation, and then blame “lifestyle” because it is cheaper than fixing the gutter.
The tenants who should expect challenge are the ones who refuse reasonable access, ignore ventilation advice, overcrowd the property, block airflow, repeatedly dry clothes indoors without ventilation, and then expect the landlord and agent to perform miracles with the basic laws of building physics.
The point is not what we assume the cause might be.
The point is what can be evidenced and a willingness from both sides to deal with the actual cause rather than the most convenient story that is cost-free.
Quoc and Tu
Sentinel - "Doing things right"
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