Damp, mould and condensation: who is responsible and how to fix it
Damp is the single most-argued issue between renters and landlords, and it is a real worry for homeowners too. The catch is that "damp" is really four different problems, condensation and black mould, penetrating damp, rising damp and internal leaks, and they do not all have the same cause, the same cost, or the same person on the hook. This plain-English guide helps you tell them apart, sets out who is responsible when you rent or own, what the fixes roughly cost, and how to get it put right. General guidance, not legal advice: confirm the current rules on gov.uk before acting.
- It is four problems, not one. Condensation and black mould, penetrating damp, rising damp and internal leaks each have a different cause and a different fix, so start by working out which you have.
- Renting? Building defects are the landlord's. Under the Landlord and Tenant Act 1985 the landlord must keep the structure, exterior and installations in repair, so damp from a fault is theirs to fix.
- "Lifestyle" is not a get-out. Persistent damp and mould is a health hazard under the Homes (Fitness for Human Habitation) Act 2018 and the HHSRS, so a landlord must investigate and tackle the cause, not just blame how you live.
- Awaab's Law sets deadlines. Binding timescales to investigate and fix damp and mould apply to social landlords from October 2025; the extension to private lets is provided for by the Renters' Rights Act and being brought in by later regulations.
- Evidence wins disputes. Dated photos and a written record of when you reported it are what a repair, deposit or enforcement case turns on, whoever is responsible.
This is a plain-English summary, not legal advice and not a survey. The rules differ across the UK nations and are being reformed, so always confirm the current position on gov.uk, and take advice from a solicitor or a service such as Citizens Advice or Shelter where a decision matters. If you want a tailored read on your own situation, our free damp and mould responsibility checker walks through it.
Condensation, rising damp or penetrating damp.
Before anyone can fix damp, or argue about who pays, you need to know which kind it is. The pattern of where it appears, when it is worst and how it behaves after rain is usually the biggest clue. Use the table as a first read, not a diagnosis: several causes can overlap, and a proper inspection settles it.
This table is a guide to the tell-tale signs, not a survey. If two or more descriptions fit, or nothing clearly matches, treat the cause as unconfirmed and get it inspected. Our damp and mould responsibility checker asks what you are seeing and explains the likely cause and who is usually responsible.
What each fix tends to cost.
Costs swing enormously with the property, the region, the extent of the problem and the installer, so treat everything below as broad, indicative ranges only, not quotes. The single most useful thing you can do before spending money is to get the cause diagnosed, because paying to fix the wrong kind of damp is the classic expensive mistake. If you rent, most of this is the landlord's cost, not yours (see the responsibility section below).
These figures are a sense of scale, not a guarantee or a quote, and grants and schemes change. Always get written quotes and, for treatment work, be wary of a "free survey" from a firm that only sells one product. For a fuller breakdown by problem type and region, use our damp-proofing cost calculator.
Who is responsible: renters and landlords.
The honest answer is that responsibility follows the cause, with an important floor underneath it. Day-to-day ventilation and heating are the tenant's part, but the building itself, and the duty not to let a home stay unfit, sits firmly with the landlord.
Building defects are the landlord's. Under section 11 of the Landlord and Tenant Act 1985, a landlord must keep the structure and exterior in repair and keep the installations for heating, water, gas and electrics working. So damp from a building fault, a leak, failed pointing, a bridged or failed damp-proof course, or missing or broken ventilation, is theirs to fix, and that duty cannot be signed away in a tenancy agreement. Penetrating damp, rising damp and internal leaks almost always fall here.
Condensation is the grey area, but not a free pass for the landlord. Condensation and black mould can come from how a home is heated and aired, which is partly the tenant's role, or from a building fault such as a broken extractor fan, no window vents, cold-bridging or poor insulation, which is the landlord's, and it is very often a mix of both. Crucially, a landlord can no longer simply blame "tenant lifestyle" and walk away: persistent damp and mould is a health hazard the landlord has to investigate and address.
The fitness backstop. The Homes (Fitness for Human Habitation) Act 2018 requires a rented home to be fit to live in for the whole tenancy, and freedom from serious damp and mould is one of the matters that fitness is judged against. If a home is not fit, a tenant can ask the court to order the landlord to carry out repairs and to pay compensation, without waiting for the council.
The council's power. Separately, the Housing Health and Safety Rating System (HHSRS) lets a council's environmental-health team assess damp and mould as a hazard and order the landlord to remedy it. The most serious level, a Category 1 hazard, the council has a duty to act on. This route is open to both private and social tenants.
Awaab's Law and the timescales. Awaab's Law sets binding timescales for a landlord to investigate a reported damp and mould hazard and begin fixing it. It is in force for social landlords for damp and mould from October 2025. Its extension to the private rented sector is provided for by the Renters' Rights Act and is being brought in by later regulations, so for private lets it is coming, not yet in force. Until then, the Fitness Act and the HHSRS above already apply to private tenancies, so there is a duty on a private landlord regardless. The wider tenancy reforms are covered in our Renters' Rights Act guide.
What this means in practice. Report the problem in writing and keep a dated copy, ventilate and heat the home while you wait, but do not let that be used to dismiss a building fault. If it is not dealt with, the record of what you reported and when is what a repairs claim, a deposit dispute or a council referral turns on. Free, independent help is available from Citizens Advice and Shelter.
Homeowners: when damp is serious.
As an owner-occupier the responsibility is all yours, which makes getting the diagnosis right even more important. Most damp is a maintenance issue you can plan and stage, but some of it is a signal of a structural problem worth taking seriously.
When to treat it as urgent. A spreading patch that keeps returning, timber that feels soft or springy, a musty smell that will not shift, or bulging and crumbling plaster can point to sustained water ingress, rot or a failing structure rather than simple surface condensation. Water damage escalates quickly, so the sooner the source is stopped, the smaller the bill tends to be.
Get a proper survey before you spend. An independent damp and timber survey, ideally from a surveyor who diagnoses rather than only sells treatments, will identify the cause and steer you away from unnecessary work. Rising damp in particular is over-diagnosed, and a chemical damp-proof course is sometimes sold where the real problem was a leak, condensation or bridging that a cheaper fix would have solved. If you are buying, a build-quality issue like this is exactly what a full building survey exists to flag.
The insurance angle. Standard buildings insurance usually does not cover gradual damp, condensation or general wear, which insurers treat as maintenance. It may cover sudden, one-off damage from an insured event, for example an escape of water from a burst pipe or storm damage that lets water in, subject to your policy wording and excess. Read your own policy and speak to your insurer before assuming cover either way, and keep photos and dates in case you do claim.
Keep the paper trail. Whether you fix it now or stage it, keeping quotes, survey reports, before-and-after photos and receipts together makes the next sale, remortgage or insurance claim far smoother. Our inspection and inventory report is built for exactly that kind of dated record, and if a boiler or heating decision is part of the picture, our new boiler cost calculator can help you size it up.
Ventilation, heating and when it is a building fault.
For everyday condensation and black mould, the cheap basics usually do most of the work, and they are worth doing whether you rent or own. The goal is to make less moisture, move it out, and stop cold surfaces for it to land on.
Cut the moisture at source. Use extractor fans when cooking and showering and leave them running for a while afterwards, put lids on pans, wipe down streaming windows, and avoid drying washing indoors on radiators without ventilation. Keeping bathroom and kitchen doors shut while in use stops the moisture spreading to colder rooms.
Ventilate, even in winter. Open trickle vents where the windows have them, air rooms briefly each day, and do not block air bricks or permanent vents. A small, steady change of air removes far more moisture over a day than one big blast.
Keep a low background heat. Cold surfaces are where condensation forms, so a low, steady warmth across the home is more effective against mould than heating one room hard and leaving the rest cold. This is genuinely harder in an under-insulated or expensive-to-heat home, which is part of why poor insulation can point back to a building fault.
When a dehumidifier helps. A dehumidifier can take the edge off a persistently humid home, dry out a room after a leak, or help while you sort a longer-term fix. It manages the symptom, it does not repair a defect, so if you are constantly emptying one, that is a sign the underlying cause, ventilation, insulation or a building fault, still needs addressing.
When it is clearly the building. If the mould keeps coming back despite sensible heating and ventilation, if there is no working extractor fan, if the windows have no vents, or if the damp is a defined patch, a tide mark or tied to plumbing, it is not a lifestyle problem, it is a building one. Penetrating damp, rising damp and leaks need the defect itself fixed, not a dehumidifier, and if you rent, that is the landlord's job.
How to escalate, with evidence.
If you have reported damp and mould and nothing is happening, the strength of your position comes down to the record you have kept. Build the evidence first, then step it up.
Keep dated evidence. Photograph the mould or the patch, and photograph a penetrating-damp patch again after heavy rain so the pattern shows. Note the dates, keep copies of every message reporting it, and record what was said and done in reply. This dated trail is what a repairs claim, a deposit dispute or a council or ombudsman case is built on.
Report it formally and give a reasonable chance to act. Put the problem in writing to the landlord or agent, describe it clearly, and keep the copy. If a letting or managing agent is involved, they must belong to a redress scheme you can complain to if they fail to act.
Environmental health. For a serious hazard that is not being dealt with, your council's environmental-health team can inspect under the HHSRS and order the landlord to remedy it. This route is open to private and social tenants and does not depend on going to court.
The ombudsman routes. Social housing tenants can escalate to the Housing Ombudsman once the landlord's own complaints process is exhausted. For private tenants the main statutory route is environmental health above, though a dedicated ombudsman for private landlords is provided for by the Renters' Rights Act and being introduced. Free, independent advice on the right next step is available from Citizens Advice and Shelter.
Let Stead hold the trail. Stead keeps a dated record of what you reported and when, holds your photos and documents in one place, and the app's report-a-repair builder quotes the landlord's repairing duties for you, so if it is not sorted you have the paper trail to push it. Keep a dated record in Stead, or size up the work with our damp-proofing cost calculator.
Damp and mould FAQs.
How do I tell condensation, rising damp and penetrating damp apart?
Condensation with black mould is worst in cold weather and the least-heated rooms, showing as black speckled mould in corners, behind furniture and around streaming windows. Penetrating damp is a defined patch on an external wall or chimney breast that darkens after heavy rain and dries between. Rising damp is a horizontal tide mark up to about a metre on a ground-floor wall, sometimes with blown plaster or salts, though genuine rising damp is rarer than people think. A leak is localised to plumbing. This is general guidance, not a survey, so get the cause diagnosed if it is unclear.
Is damp and mould my landlord's responsibility or mine?
Damp from a building defect, such as a leak, failed pointing, a bridged damp-proof course or missing ventilation, is generally the landlord's to fix under section 11 of the Landlord and Tenant Act 1985, which requires them to keep the structure, exterior and installations in repair. Day-to-day ventilation and heating are the tenant's part, but persistent damp and mould is a health hazard the landlord must investigate and tackle under the Homes (Fitness for Human Habitation) Act 2018 and the HHSRS, whatever the cause.
Can a landlord blame damp on my lifestyle?
Not as a way to avoid acting. A landlord can no longer simply blame tenant lifestyle: persistent damp and mould is a hazard under the Fitness Act and the HHSRS, and the landlord must investigate and address the cause. You still have a part to play in ventilating and heating the home, but that cannot be used to dismiss a genuine building fault such as a broken extractor fan, poor insulation or cold-bridging.
What is Awaab's Law and does it apply to private renters?
Awaab's Law sets binding timescales for a landlord to investigate and begin fixing a reported damp and mould hazard. It is in force for social landlords for damp and mould from October 2025. Its extension to the private rented sector is provided for by the Renters' Rights Act and is being brought in by later regulations, so it is coming, not yet in force for private lets. Until then the Fitness Act and the HHSRS already apply to private tenancies. Check gov.uk for the current position.
Does home insurance cover damp?
Usually not for gradual damp, condensation or general wear, which standard buildings insurance treats as maintenance rather than an insured event. However, sudden one-off damage from an insured event, such as an escape of water from a burst pipe or storm damage that lets water in, may be covered, subject to your policy wording and excess. Always read your own policy and speak to your insurer before assuming cover either way.
How much does it cost to fix damp?
It depends entirely on the cause. Fitting or replacing an extractor fan is often around £100 to £300, a positive input ventilation unit roughly £400 to £900 fitted, and a dehumidifier around £100 to £300 to buy. An independent damp survey is often around £150 to £400 or more. Penetrating damp repairs range from a few hundred to low thousands, and a damp-proof course with replastering for genuine rising damp is often around £1,000 to £3,000 or more. These are broad indicative ranges, not quotes.
When should I contact environmental health or an ombudsman?
If a serious damp and mould hazard is not being dealt with, your council's environmental-health team can assess it under the HHSRS and order the landlord to act, and this route is open to private and social tenants. Social housing tenants can also escalate to the Housing Ombudsman after exhausting the landlord's complaints process. Where a letting or managing agent is involved they must belong to a redress scheme, and a dedicated ombudsman for private landlords is provided for by the Renters' Rights Act and being introduced.
This guide is general information about damp, mould and condensation in UK homes, not legal advice or a survey, and it does not create a professional relationship. Repairing duties, the fitness standard and the rules on hazards differ across the UK nations and are being reformed, and Awaab's Law for the private rented sector is provided for by the Renters' Rights Act but is being brought in by later regulations rather than already in force. Before acting on anything here, confirm the current position on gov.uk, use a qualified surveyor or a suitably qualified contractor for any work, and take advice on your own home where it matters.
Damp disputes come down to evidence.
Stead keeps a dated record of what you reported and when, holds your photos and documents in one place, and the app's report-a-repair builder quotes your landlord's repairing duties for you, so if it is not sorted, you have the paper trail to push it.