Damp & Mould in Rental Properties: A Landlord's Complete Guide

Damp and mould are among the most serious hazards a landlord can face. Not just because of the damage to your property, but because of the real health risks to tenants and the growing legal duties that apply to all landlords.

This guide breaks down everything you need to know: what causes damp and mould, your legal obligations, what Awaab's Law means for you, and how to respond properly when a tenant raises a concern.

The Three Types of Damp: How to Tell Them Apart

Not all damp is the same, and the treatment varies depending on the cause. Misidentifying the type of damp is one of the most common and costly mistakes landlords make.

1. Condensation damp

The most common type in UK rental properties. Caused by warm, moist air meeting cold surfaces, typically on windows, external walls, and in bathrooms. Often mistaken for a structural problem when it's actually a ventilation issue.

• Black mould spots on walls, ceilings, and around window frames
• Condensation on windows and cold external walls
• Musty smell, particularly in bathrooms and bedrooms
• Often worse in winter and in poorly ventilated rooms

2. Penetrating damp

Water getting in from outside through a defect in the building fabric: a leaking roof, broken guttering, cracked render, or failed pointing. This is a structural issue and is the landlord's responsibility to fix.

• Damp patches that spread outward from a fixed point
• Tide marks or brown staining on walls
• Damp that appears or worsens after heavy rain
• Often linked to a visible defect externally

3. Rising damp

Groundwater wicking up through the walls or floor. Less common than often claimed. Genuine rising damp requires the absence or failure of a damp-proof course. Look for a classic 'tide mark' at low level, salt crystallisation, and plaster damage.

Your legal duties as a landlord

Under the Landlord and Tenant Act 1985 and the Housing Act 2004, landlords are required to keep rental properties free from serious hazards, including Category 1 HHSRS hazards, of which damp and mould is one.

The Homes (Fitness for Human Habitation) Act 2018 (the 'Fitness Act') extended these duties to all tenancies, giving tenants the right to take landlords to court if the property is not fit for human habitation. Serious damp or mould falls squarely within this.

Awaab's Law: what every landlord needs to know

Awaab Ishak was a two-year-old boy who died in December 2020 in Rochdale from a respiratory condition caused by prolonged exposure to mould in his social housing flat. The landlord had been made aware of the mould and had failed to act.

Awaab's Law, introduced as part of the Social Housing (Regulation) Act 2023, places new legal duties on social landlords to investigate and remediate health hazards, including damp and mould, within strict timeframes:

1. 1Landlords must acknowledge a damp or mould complaint within 24 hours
2. 2An investigation must be completed within 14 days
3. 3Remediation must begin within 7 days of the investigation
4. 4In emergency cases, hazards must be fixed within 24 hours

What to do when a tenant reports damp or mould

The single most important thing is to act quickly and document everything. Failing to respond is both a legal and commercial risk.

1. 1Acknowledge the report in writing (email is fine). Same day if possible.
2. 2Arrange an inspection. A professional survey is far stronger evidence than a landlord's own assessment.
3. 3Identify the cause: condensation, penetrating, or structural
4. 4Take photographs and record all findings in writing
5. 5Carry out the remediation works promptly. Do not delay.
6. 6Follow up with the tenant to confirm the issue is resolved
7. 7Keep all records: correspondence, survey reports, invoices

What is an HHSRS-compliant survey?

The Housing Health and Safety Rating System (HHSRS) is the framework used by local authorities to assess housing hazards. A Category 1 hazard is one that poses a serious risk to health and must be remediated.

An HHSRS-compliant damp and mould survey includes: a full visual inspection, thermal imaging, moisture readings, humidity assessment, mould classification, a risk rating, and a written report with remedial recommendations. It is the document that demonstrates you have taken the matter seriously and assessed it properly.

Our specialist division, The Damp & Mould Man, provides HHSRS-compliant surveys from £100. If the survey identifies work that needs doing, our in-house team can carry it out. One contractor, one invoice.