TL;DR: Yes, damp is dangerous — it causes respiratory problems, allergies, and structural damage. There are three types: condensation (most common, caused by poor ventilation), rising damp (moisture from the ground), and penetrating damp (water from outside). Treatment costs range from £200 for ventilation improvements to £6,000+ for full damp-proofing. Landlords are legally responsible for fixing damp in rental properties.
Last updated: April 2026
Is Damp Dangerous to Health?
Yes. The NHS states that living in a damp or mouldy home can cause or worsen:
- Respiratory infections — bronchitis, pneumonia
- Allergic reactions — sneezing, runny nose, red eyes, skin rashes
- Asthma — damp is a known trigger for asthma attacks
- Weakened immune system — particularly in children and the elderly
In 2020, two-year-old Awaab Ishak died from prolonged exposure to mould in his family's housing association flat in Rochdale. This tragedy led to Awaab's Law (2024), which requires social landlords to investigate and fix damp and mould hazards within strict timeframes.
The Three Types of Damp
1. Condensation (Most Common — 90% of Cases)
What it is: Moisture from everyday activities (cooking, bathing, drying clothes, breathing) that settles on cold surfaces.
Signs:
- Water droplets on windows, especially in the morning
- Black mould on walls, ceilings, and around windows
- Musty smell, particularly in bedrooms and bathrooms
- Damp patches on external walls (usually upper parts)
Causes:
- Poor ventilation — extractors not working or not used
- Drying clothes indoors without ventilation
- Cold surfaces — single-glazed windows, uninsulated walls
- Overcrowding — more people generate more moisture
Treatment cost: £200-£1,000
- Extractor fans: £150-£300 each installed
- Positive input ventilation (PIV): £400-£800 installed
- Dehumidifier: £100-£300
- Improved insulation: varies
2. Rising Damp
What it is: Moisture drawn up from the ground through walls by capillary action, usually where the damp-proof course (DPC) has failed or is absent.
Signs:
- Tide mark or staining up to 1 metre high on ground-floor walls
- Damaged or crumbling plaster at the base of walls
- White salt deposits (efflorescence) on walls
- Peeling wallpaper or paint near the floor
- Rotten skirting boards
Treatment cost: £300-£1,000 per wall, £2,000-£6,000 for a whole house
- Chemical DPC injection: £300-£700 per wall (most common treatment)
- Re-plastering with salt-resistant plaster: £40-£60/m²
- External ground level reduction: £200-£500
3. Penetrating Damp
What it is: Water entering the building from outside through walls, the roof, or around windows and doors.
Signs:
- Damp patches on walls that get worse during heavy rain
- Localised damp around windows, doors, or chimneys
- Damp on upper floors (unlikely to be rising damp)
- Staining or water marks on ceilings
Common causes:
- Failed pointing or rendering
- Cracked or missing roof tiles
- Blocked or damaged gutters and downpipes
- Failed window seals
- Defective flashing
Treatment cost: depends on the cause
- Repointing: £25-£50/m² (£2,000-£5,000 for a house)
- Gutter repair/replacement: £200-£600
- Roof repair: £200-£1,000
- Re-rendering: £30-£60/m² (£4,000-£8,000 for a house)
How to Identify Which Type of Damp You Have
| Feature | Condensation | Rising Damp | Penetrating Damp |
|---|---|---|---|
| Location | Windows, external walls, ceilings | Base of ground-floor walls (up to 1m) | Anywhere — follows the water source |
| Pattern | Widespread, often with mould | Horizontal tide mark | Localised patches |
| Worse when | Cold weather, poor ventilation | Year-round (but more visible in summer) | During or after heavy rain |
| Mould? | Common — black mould on surfaces | Rare on walls, but skirting boards may rot | Possible in persistent cases |
| Salt deposits? | No | Yes — white crystals on walls | No |
Tenant Rights: Is My Landlord Responsible?
Under the Homes (Fitness for Human Habitation) Act 2018, landlords must ensure rental properties are fit for habitation throughout the tenancy. Damp and mould that make a property unfit is the landlord's responsibility to fix.
Awaab's Law (part of the Social Housing (Regulation) Act 2023, in force from 2024) requires social landlords to:
- Investigate reports of damp and mould within 14 calendar days
- Begin repair work within 7 calendar days of investigation
- Complete emergency repairs within 24 hours if there is an immediate health risk
What to do if your landlord won't act:
- Report the issue in writing (email or letter) and keep copies
- Take photographs with dates as evidence
- Contact your local council's Environmental Health team
- Seek advice from Shelter or Citizens Advice
When to Get a Professional Survey
A professional damp survey costs £200-£400 and is recommended if:
- You are unsure of the type of damp
- Damp keeps returning after treatment
- You are buying or selling a property
- There is extensive damage to plaster, timber, or decoration
Always use a PCA-registered surveyor (Property Care Association) for independent, reliable assessments.
Next Steps
Concerned about damp in your home? Get free, no-obligation quotes for damp surveys and treatment from certified specialists through Better Home Hub.