Complete Damp &
Mould Guide 2026

Not all damp is the same. Misdiagnosis is common and leads to ineffective treatment. A professional survey will identify which type you have — or whether multiple types are present simultaneously. RISING DAMP Rising damp occurs when groundwater travels upward through the walls of a building by capillary action. It is typically identified by a tide mark on walls, usually no higher than 1 metre from the floor, salt staining, and peeling paint or wallpaper at low level. Rising damp is caused by a failed or absent damp proof course (DPC) — the horizontal barrier installed in walls to prevent moisture migration. PENETRATING DAMP Penetrating damp enters a building horizontally through the external fabric — walls, roof, windows, or floors. Common causes include defective pointing, cracked render, blocked or damaged guttering, leaking windows, and flat roof failures. Unlike rising damp, penetrating damp can appear at any height on a wall and is often worse after rain. CONDENSATION Condensation is by far the most common form of damp in UK homes, accounting for the majority of damp complaints. It occurs when warm, moisture-laden air meets cold surfaces such as windows, external walls, and cold spots around thermal bridges. Condensation is largely a ventilation and insulation problem rather than a structural one. Mould growth — black mould in particular — is almost always a symptom of condensation rather than rising or penetrating damp.

The health risks of living with damp and mould are serious and well-documented. Mould produces spores and mycotoxins that, when inhaled, can cause and worsen a range of health conditions. Groups most at risk include: • Infants and young children • Elderly people • Those with asthma or other respiratory conditions • People with allergies or compromised immune systems Documented health effects include: respiratory infections, worsening asthma, allergic rhinitis, skin irritation, fatigue, and in severe cases, hypersensitivity pneumonitis. The death of two-year-old Awaab Ishak in Rochdale in 2020 — caused by prolonged exposure to mould in his family's social housing — prompted legislative change. The resulting Awaab's Law has fundamentally changed landlord obligations in England.

Awaab's Law, introduced under the Social Housing (Regulation) Act 2023, applies initially to social landlords and is being extended to the private rented sector. It establishes fixed timeframes for responding to damp and mould hazards. Current requirements for social landlords: • Investigate damp and mould hazards within 14 days of a complaint • Begin emergency repairs within 24 hours where there is an immediate risk to health • Begin non-emergency repairs within 7 days of investigation • Complete all repairs within a reasonable timeframe For private landlords, the existing obligations under the Housing Health and Safety Rating System (HHSRS) and the Landlord and Tenant Act 1985 already require properties to be kept in good repair and free from category 1 hazards — which include damp and mould. Practical implications for landlords: • Document all damp complaints in writing immediately • Commission a professional survey within 14 days of any complaint • Keep records of all remedial works carried out • Do not rely on informal repairs — obtain written reports Failure to act exposes landlords to Housing Ombudsman complaints, local authority enforcement, and civil claims from tenants.

A professional damp survey conducted by a CSRT (Certificate in Remedial Waterproofing Technology) or CSSW (Certificate in Structural Waterproofing) qualified surveyor follows a structured process. Initial inspection: The surveyor will visually inspect affected areas, noting the location, extent, and pattern of dampness. They will assess external factors including guttering, pointing, render, ground levels, and drainage. Moisture readings: Using calibrated moisture meters, the surveyor will take readings across affected walls, floors, and timbers to map moisture levels and identify the extent of penetration. Diagnosis: Based on visual inspection, moisture readings, and the pattern of dampness, the surveyor will diagnose the type or types of damp present. A good surveyor will clearly distinguish between rising damp, penetrating damp, and condensation rather than applying a blanket diagnosis. Written report: You will receive a formal written report documenting findings, diagnosis, and recommended remedial works including indicative costs. This report is essential for insurance claims, landlord compliance records, and obtaining contractor quotes. A professional survey typically takes 1–3 hours for a standard property.

Professional damp survey costs in London (2026): • Studio / one-bedroom flat: £150–£250 • Two to three bedroom house: £250–£400 • Larger property / commercial: £400–£800+ Be cautious of free surveys offered by damp proofing companies. These are sales tools, not independent professional assessments. An independent surveyor has no financial interest in recommending expensive remedial works. Always use a surveyor who is a member of the Property Care Association (PCA) or holds CSRT/CSSW qualifications from the Certificated Surveyor in Remedial Treatment scheme.

The appropriate remedy depends entirely on the type and cause of damp identified. CONDENSATION • Improved ventilation: PIV (Positive Input Ventilation) units £400–£700 installed • Mechanical extract ventilation in kitchens/bathrooms: £150–£300 per room • Improved insulation to eliminate cold spots • Mould treatment and redecoration: £300–£800 depending on extent RISING DAMP • Chemical damp proof course injection: £800–£2,500 depending on wall length • Re-plastering with salt-resistant plaster: £1,000–£3,000+ • Drainage improvements where ground levels are an issue PENETRATING DAMP • Repointing: £300–£800 for a typical elevation • Render repair or replacement: £1,500–£5,000+ • Gutter repair or replacement: £200–£600 • Window resealing or replacement: varies Costs vary significantly by contractor, access, and extent of damage. Always obtain three written quotes and ensure works are guaranteed in writing.

Tenants have clear legal rights when it comes to damp and mould. Under the Landlord and Tenant Act 1985, landlords are required to keep properties in good repair and free from hazards that affect health. Steps for tenants: 1. Report in writing: Email or text your landlord or letting agent documenting the damp or mould. Keep a copy. Include photographs with dates. 2. Give reasonable time to respond: For non-emergency issues, landlords typically have 14–21 days to respond. For urgent health risks, 24–48 hours is reasonable. 3. Escalate if ignored: If your landlord fails to act, contact your local council's Environmental Health department. They have powers to inspect and issue improvement notices. 4. Housing Ombudsman: If you are in social housing, you can complain to the Housing Ombudsman if your landlord fails to comply with Awaab's Law timeframes. 5. Legal action: As a last resort, tenants can pursue landlords through the courts for breach of the implied covenant of quiet enjoyment and breach of statutory duty. Keep all correspondence. Photograph everything. This documentation is essential if the matter escalates.