Mould in a Rental Property: Who Is Responsible and What to Do

In most cases the landlord is responsible when mould in a rental property comes from the building: a leak, rising or penetrating damp, poor ventilation or missing insulation. Tenants share the load where day-to-day habits add moisture, but the law expects a home to cope with normal occupancy. This guide covers the duties on each side, what Awaab’s Law does and does not cover in private lettings today, and how to deal with the cause rather than the stain. It is written for England. Rules in Scotland, Wales and Northern Ireland differ.

TL;DR

• Landlords must keep a let home fit for human habitation under the Homes (Fitness for Human Habitation) Act 2018. Damp and mould are part of that duty.
• Awaab’s Law, with fixed deadlines, applies to social landlords now. Its extension to private rentals is set by the Renters’ Rights Act 2025, but the date is still unconfirmed.
• Blaming a tenant’s lifestyle is rarely a defence if the building has ventilation, insulation or structural faults.
• Report in writing, keep photos and dates, and give access for inspection.
• Wiping or painting over mould is not a fix. The moisture source has to be found and treated.

Who is responsible for mould: landlord or tenant?

There is no single answer, because mould is a symptom. The responsibility follows the cause of the moisture.

The government guidance on the health risks of damp and mould is clear that landlords should not simply blame occupant behaviour. Where structural problems, inadequate ventilation or a lack of insulation are present, the landlord is expected to resolve those underlying deficiencies. Normal living produces moisture. A habitable home has to allow for it.

That matters for a very common situation: a flat with a small bathroom, no working extractor and cold external walls. Showers and cooking create steam, the walls are cold, and mould forms behind wardrobes. Calling that a tenant problem ignores that the property lacks the means to remove moisture.

What the law says for private landlords

The main duty sits in the Homes (Fitness for Human Habitation) Act 2018. It requires landlords to let homes that are fit to live in at the start of the tenancy and throughout it. According to the government’s guide for tenants, damp and mould growth can make a home unfit, and landlords must then put right the defects causing it.

Three practical points follow.

1. The duty arises when the landlord knows. The Housing Ombudsman notes that many tenants do not realise the duty to repair begins once the landlord is aware of the problem. A message to the agent counts as notice if it is on record.
2. Local councils can act. Environmental health teams assess homes under the Housing Health and Safety Rating System, which treats damp and mould as a hazard category. A tenant who gets no response can ask the council to inspect.
3. Retaliation is a separate worry. Tenants often hesitate to complain. The Renters’ Rights Act 2025 strengthens tenant security, which is one reason landlords are better off fixing the problem early than defending it later.

Awaab’s Law: what applies now and what is coming

Awaab’s Law came into force for the social rented sector on 27 October 2025. It is named after Awaab Ishak, a two-year-old who died from exposure to mould in a housing association home. Under the official timeframes guidance, social landlords must:

• investigate emergency hazards and make them safe within 24 hours;
• investigate significant damp and mould hazards within 10 working days;
• send the tenant a written summary of findings within 3 working days of the investigation ending;
• make the home safe within 5 working days where a significant hazard is confirmed;
• begin any further preventative work within 5 working days of the investigation, or within 12 weeks where the work is not immediate.

Does it apply to a private tenancy?

Not yet. The Renters’ Rights Act 2025 provides for the extension of Awaab’s Law to private rentals, and North Herts Council explains that this is expected in a later phase, with the exact date still to be confirmed as of October 2026. Private landlords therefore have no statutory clock today, but they are still bound by the fitness duty, the council’s enforcement powers and the ordinary repairing obligations.

The sensible approach for a landlord is to treat the social-sector timescales as the benchmark now. Property managers who build a process around 10 working days to investigate and a written summary will not be caught out when the rules arrive. Our own guides explain Awaab’s Law for landlords and property managers and what compliance looks like in Dorset and Hampshire.

What counts as a significant hazard?

Size alone does not decide it. The vulnerability of the occupants matters: young children, people with asthma or COPD, older residents or anyone with a weakened immune system. A small patch above the bed of a child with asthma can be a higher priority than a larger patch in a spare hallway. Landlords who triage by square metres alone risk under-reacting. Our article on mould remediation and the 1 m² trigger covers how that threshold is used and where it falls short.

Why mould appears in rented homes

Mould needs moisture, a food source (paint, wallpaper, plaster, dust) and time. It tends to show as black, white or green spots, and often forms in corners, behind furniture and around window frames. The causes fall into a handful of groups.

Condensation

Warm, moist air meets a cold surface and turns to water. It is the most common cause in lettings, and it is where the landlord and tenant argument usually starts. Solutions include working extractor fans, trickle vents, wall and loft insulation, and heating that can be afforded. The Housing Ombudsman describes damp as a build-up of moisture that can follow leaks, poor property condition or structural problems. Our guide on damp versus condensation shows how to tell the two apart, and the page on condensation and moisture control sets out the remedies.

Penetrating damp

Water enters through the structure: failed pointing, cracked render, defective gutters, a leaking roof or a faulty window reveal. It leaves a patch that grows after rain. This is nearly always the landlord’s responsibility, because it is a repair issue. One of our Bournemouth jobs shows penetrating damp in a kitchen wall resolved with an internal drying system and masonry protection.

Rising damp

Ground moisture travels up masonry where the damp-proof course has failed or been bridged. It leaves tide marks and salt deposits low on the wall. Older stock is most affected, and treatment usually means a chemical DPC injection or an internal membrane. See the Victorian home case in Dorchester and the rising damp versus condensation guide.

Hidden moisture

Sometimes there is a musty smell and no visible growth. Mould may be behind a wall lining, under flooring or in a void. The Housing Ombudsman’s advice is to avoid pulling up carpets or stripping wallpaper yourself, since disturbing hidden growth can release concentrated spores. A professional assessment is the safe route.

What tenants should do

The aim is to get the cause fixed and to keep a record that stands up if the landlord does not respond.

1. Photograph the mould with dates, including the wider room and any damaged belongings.
2. Report in writing by email or through the agent’s portal. A phone call alone leaves no trace. The Ombudsman stresses that a dated paper trail is what supports a later claim under the 2018 Act or Awaab’s Law.
3. Allow access. Shelter’s advice is that the landlord must try to find the cause and tenants should give access for inspection, on agreed dates.
4. Reduce moisture sensibly while waiting: use extractor fans, keep furniture slightly off cold external walls, and ventilate after showering. None of this replaces a repair.
5. Do not scrub large areas or disturb hidden growth if anyone in the home has asthma, allergies or a lung condition. Speak to a GP about symptoms.
6. Escalate to the local council’s environmental health team if the landlord does not act, or use the landlord’s complaints procedure first where one exists.

Tenants who document the starting condition of a home carefully are better placed in disputes. Good tenancy cleaning and inventory records help show what the property looked like at move-in, which protects a deposit and helps separate pre-existing damp from damage later.

What landlords should do

Respond fast and in writing

Acknowledge the report, set an inspection date, and send a written summary of what was found and what will be done. In social housing the written summary is a legal step within 3 working days. In private lettings it is simply good evidence, and many landlords skip it.

Find the cause before choosing the treatment

Surface cleaning and a coat of paint hide the problem for a few months. Mould returns when the moisture source is still there. A proper survey measures moisture content, checks the fabric and ventilation, and separates condensation from penetrating or rising damp. The spend then goes on the right fix: a gutter repair, a DPC, a tanking system, a new extractor or insulation.

Treat the property, not the tenant

Guidance cautions against pinning the problem on tenant lifestyle when the property has structural issues, poor ventilation or no insulation. Advice to tenants on ventilation is reasonable, but it should come after the building has been put right. A landlord who also handles other maintenance, such as the decorating duties that follow a repair, should schedule redecoration only once the wall is dry and the cause is dealt with. Painting first just buries the evidence.

Re-inspect after the work

The government guidance recommends checking back at least six weeks after remedial work, to confirm that the fix has worked. Surface mould removed without addressing the source often returns within that window, and a follow-up visit catches it before the tenant has to complain again.

Keep records

Store survey reports, photographs, invoices, guarantees and tenant correspondence. They show that the landlord acted, and an insurance-backed guarantee on the treatment adds a layer of protection for the next owner or tenant.

Treatment options by cause

Our mould removal and air quality service is designed to sit alongside the root-cause repair, not replace it. Where moisture has reached joists, skirting or floors, timber treatment deals with decay that would otherwise carry on behind the surface.

Our view as specialists

We see the same pattern on many lettings across Dorset, Hampshire and Wiltshire. A tenant reports mould. The first response is a mould wash and a leaflet on opening windows. The patch returns, the tenant reports again, and by the third visit the relationship is strained and the wall is no better.

The common thread is a missing diagnosis. Condensation, penetrating damp and rising damp can all produce black mould on a wall, and each needs a different repair. A treatment chosen by guesswork either fails or fixes only part of the issue. That is why every job starts with a survey that identifies the source of the moisture, followed by a written report setting out what we found and what we recommend.

We also think the line between landlord and tenant is drawn too early. If a home needs a heater running all day and every window open to avoid mould, the home is the problem. Ventilation and insulation upgrades are cheaper than repeated redecoration, void periods and disputes, and they make the property easier to let.

Finally, all of our work is carried out by our own in-house specialists, not subcontractors, and treatment work carries a 25-year insurance-backed guarantee. For a landlord, that means one accountable team from survey to completion and paperwork that can be handed to an agent, a tenant or a buyer.

— Proofterior

Getting a survey for a let property

Landlords, letting agents and property managers in Dorset, Hampshire and Wiltshire can book a complimentary property survey. It identifies the cause of the damp or mould, and a detailed written report follows, which doubles as a record of the action taken. If you want to know what the visit involves first, read what happens during a complimentary damp survey. The full range of treatments is listed on our services page.

FAQ

Can a landlord evict a tenant for complaining about mould?

The Renters’ Rights Act 2025 strengthens tenant security and is intended to make it harder to remove a tenant for raising repair issues. Exact rules depend on the commencement of each part of the Act, so tenants worried about this should check current guidance with Shelter or a local advice service. Keep all complaints in writing.

How long does a landlord have to fix mould?

For social landlords, Awaab’s Law sets 10 working days to investigate significant damp and mould and 5 working days to make the home safe once a hazard is confirmed. Private landlords have no fixed statutory deadline yet, but must act within a reasonable time under the fitness duty. A delay of months is hard to defend.

Is mould from condensation the tenant’s fault?

Not automatically. If the home has no working extraction, poor insulation or cold bridges, the landlord is expected to address those. Tenants are asked to ventilate and heat reasonably, but the building has to cope with ordinary use.

Should I clean the mould myself?

Small patches of surface mould can be cleaned if nobody in the home has asthma, allergies or a weakened immune system. Do not strip wallpaper or lift carpets where you only smell damp, since this can disturb hidden growth. Ask the landlord for an assessment instead and see a GP if anyone has breathing symptoms.

Sources

• Understanding and addressing the health risks of damp and mould in the home, GOV.UK
• Homes (Fitness for Human Habitation) Act 2018: guide for tenants, GOV.UK
• Awaab’s Law: timeframes for repairs in the social rented sector, GOV.UK
• Awaab’s Law, North Herts Council
• Damp and mould FAQs, Housing Ombudsman
• Damp and mould support guide, Housing Ombudsman
• Damp and mould in private rented homes, Shelter England

Recommended

• Mould Law for Landlords 2025
• Mould Remediation for UK Landlords: Awaab’s Law and the 1 m² Trigger
• Awaab’s Law for Landlords & Managers
• Bathroom Mould Treatment: Remove It and Stop It Returning