Damp, Mould and the Law: What Landlords Must Do in 2026

By RentVault Team · Published 2026-08-04 · 6 min read

Damp and mould are the most common serious hazards found in English rental properties.

Damp and mould are the most common serious hazards found in English rental properties. They are also the hazard most likely to generate a complaint, trigger local authority enforcement, result in a rent repayment order, or — as the regulatory landscape develops — generate significant liability for landlords who fail to act.

This article explains the current legal position for private landlords, how the HHSRS assessment framework applies to damp and mould, and what landlords need to do to manage this hazard properly. As a building surveyor, I also want to be clear about something that the general guidance rarely addresses: there is no single thing called "damp". Getting the response right depends entirely on identifying what type of damp you are dealing with.

The current legal position

The Housing Health and Safety Rating System (HHSRS) is the legal framework used by local authorities in England to assess hazards in residential properties. Damp and mould is Hazard 1 under the HHSRS — the first and most significant category.

From 23 June 2026, the HHSRS has been simplified from 29 hazards to 21. Damp and mould remains a Category 1 hazard under the revised system. A Category 1 hazard is one that poses a serious threat to health and safety. When a local authority identifies a Category 1 hazard in a rental property, it has a duty to take enforcement action — it is not discretionary.

Enforcement can include an improvement notice (requiring you to fix the problem within a specified timescale), a prohibition order (restricting use of the property), or a hazard awareness notice. Failure to comply with an improvement notice can result in prosecution and fines.

The Renters' Rights Act 2025 has also substantially increased the penalties available to local authorities. Fines of up to £7,000 for a first breach of landlord duties, and up to £40,000 for serious or repeat breaches, are now available.

What Awaab's Law means — and the anticipated future position for private landlords

Awaab's Law was introduced following the death of toddler Awaab Ishak from mould-related illness in a social housing property. It requires social housing landlords to investigate and remedy serious hazards within defined timeframes.

As of mid-2026, Awaab's Law applies to social housing landlords, not private landlords. The Renters' Rights Act 2025 contains the legal framework to extend it to the private rented sector — but the commencement date and specific timeframes have not been set.

This means private landlords do not currently face Awaab's Law timeframes. Landlords who build robust damp and mould response systems now will be better prepared for anticipated future private-rented-sector regulation. Regardless of future changes, private landlords must continue to meet their existing repair, fitness and HHSRS duties.

The three types of damp — and why the distinction matters

Most landlord guidance on damp treats it as a single problem. It is not. There are three distinct causes of damp in residential properties, and they look different, feel different, smell different, and require different remediation.

Condensation

Condensation is by far the most common form of damp in residential properties. It occurs when warm, moisture-laden air meets a cold surface — typically external walls, window reveals, and cold corners. Black mould growth (Aspergillus/Penicillium species) is the characteristic symptom.

Condensation is strongly correlated with occupant behaviour — cooking without extraction, drying clothes indoors, keeping windows permanently closed. In well-insulated properties with adequate heating and ventilation, condensation is uncommon. In poorly heated, poorly ventilated properties, it is almost inevitable.

Condensation is primarily a building deficiency, not a tenant failing — even if occupant behaviour exacerbates it. The HHSRS takes the view that a property should be capable of managing normal occupant moisture production without condensation occurring. If your property has cold surfaces (solid walls, single-glazed windows, uninsulated floor slab), inadequate extract ventilation in kitchen and bathroom, and insufficient background ventilation, it is a building problem.

Remediation typically involves improving insulation (reducing cold surfaces), improving extract ventilation in moisture-producing rooms, and improving background ventilation. Treating the mould itself — cleaning surfaces with appropriate fungicide — is also necessary, but treating the mould without addressing the underlying cause will result in recurrence.

Rising damp

Rising damp occurs when groundwater moves upward through masonry by capillary action. It is found only at low level — typically the bottom 600mm to 1 metre of a ground-floor wall. It leaves a characteristic tide mark, often with salt crystallisation and peeling plaster. Wallpaper peels at low level. The damage is distinctive.

Genuine rising damp in isolation is actually less common than many people assume — and it is frequently misdiagnosed. The mechanism requires an absence of, or a failed, damp proof course. Modern buildings with intact DPCs do not suffer from rising damp. In older buildings, diagnosis should be made by a qualified surveyor using appropriate investigation methods, not assumed from surface symptoms.

Remediation usually involves installing or repairing a damp proof course, replastering with salt-resistant render, and addressing any related drainage issues.

Penetrating damp

Penetrating damp is water entering the building through the fabric — through a defective roof, failed pointing, cracked render, a blocked or broken gutter overflowing onto a wall, failed window or door seals. Unlike rising damp, penetrating damp can appear at any height.

The symptoms depend on the source. A leaking flat roof typically shows as damp patches on the top-floor ceiling. Failed pointing shows as intermittent damp on an external wall face after rainfall. A blocked downpipe shows as a damp patch running vertically down the corner of a building.

Penetrating damp always has a specific building defect as its cause. Remediation is fixing the defect — repairing the roof covering, repointing, clearing the gutter.

Building a defensible response system

Whatever the type of damp, landlords need a documented response system that demonstrates they have investigated, identified the cause, and taken appropriate action. This supports compliance with the current HHSRS framework and provides best-practice preparation for anticipated future private-rented-sector regulation.

Respond to reports in writing. When a tenant reports damp or mould, acknowledge it in writing. Confirm you will investigate. Keep the record.

Inspect promptly. Visit the property and assess the damp. Do not rely on the tenant's description alone. Do not send someone who cannot identify the cause. If you cannot identify the cause yourself, commission a professional inspection.

Identify the type and cause. The response to condensation is fundamentally different from the response to a leaking roof. Getting this wrong results in money spent on the wrong remediation and the problem recurring.

Instruct remediation. Once you have identified the cause, instruct appropriate remediation. Keep records of the work — the contractor's invoice and any photographs of the work completed.

Check the outcome. Return after remediation to confirm the problem has been addressed. If mould has recurred, the cause has not been fully remediated.

Advise the tenant on ventilation. For condensation cases, written advice to the tenant on ventilation — opening windows, using extract fans, avoiding drying clothes indoors if possible — is reasonable. It does not transfer liability for the underlying building deficiency, but it demonstrates that you have engaged with the full picture.