Damp proofing and damp surveys

What a damp specialist does

The survey comes first. The surveyor looks for the source of the moisture, because rising damp, penetrating damp and condensation each need a different fix. Only then should you get a quote.

• Rising damp: fix ground levels and anything bridging the damp proof course. If the course has failed, a remedial damp proof course and salt-resistant plaster follow.
• Penetrating damp: repair the defect, such as gutters, pointing, render or roof coverings.
• Condensation: ventilation, heating and changes to how the home is used.

Not sure which you have? See how to identify damp.

Condensation is not a damp-proof course job

Condensation is the most common cause of mould, and a damp-proof course will not fix it. It happens when moisture from cooking, showers and laundry meets cold surfaces in a poorly ventilated, heated or insulated home. It is worst in winter.

The cure is better ventilation, such as extractor fans or a mechanical system, steady heating and drying washing outdoors. Be sceptical of anyone who quotes for injection without a clear sign of rising damp. Our DIY guide covers what occupiers can do.

What a good damp survey includes

The surveyor should inspect inside and out: walls, floors, ceilings, the roof line, gutters, downpipes, ground levels against the walls and any ventilation. They should use a moisture meter, but treat its reading as a clue, not an answer, because it cannot tell rising damp, penetrating damp and condensation apart.

Look for a written report that names the cause, gives a pattern of evidence such as the height of the damp, the season and the link to the weather, and recommends the cheapest fix that will work. A report that jumps straight to injection, with no mention of gutters, ventilation or leaks, is a warning sign.

What the work involves

After the survey, remedial work typically takes two to seven days. New plaster then needs several weeks to dry before you can decorate. You will need to clear furniture from affected walls, lift floor coverings and allow skirting boards to be stripped.

Guarantees run from 10 to 30 years. Insurance-backed options are worth asking for. PCA members can offer insurance-backed guarantees, through QANW, that continue if the contractor stops trading.

For prices, see the damp proofing cost page.

Choosing a damp surveyor

No licence is needed to treat damp. The Property Care Association (PCA) audits its members and verifies training, which is a useful signal but not a licence.

• CSTDB (Certificated Surveyor of Timber and Dampness in Buildings) and CSDB (Certificated Surveyor of Dampness in Buildings) are PCA damp surveyor qualifications.
• CSRT and CSSW (structural waterproofing) are titles you may see on older quotes or websites. We could not confirm them on the PCA's current pages, so ask for the certificate number and check it with the PCA.
• An independent survey from a surveyor who does not sell the cure is the safest start. Do not rely on a free survey from a firm that sells the treatment.

Mould and your health

Persistent damp and mould in a home is taken seriously because the Housing Health and Safety Rating System lists exposure to house dust mites, damp, mould or fungal growths as hazard 1. A 2026 change to the regulations cut the hazard list from 29 to 21 and replaced the old A to J bands with High, Medium and Low, so ignore any guide still using the old format.

If you are worried about health effects, speak to your GP, and report the problem to your landlord or council if you rent.

Renting: Awaab's Law and your rights

Awaab's Law covers social housing in England. Since 27 October 2025, landlords must investigate significant damp and mould within 10 working days, begin repairs within five working days of confirming a hazard, and deal with emergencies within 24 hours.

Phase 2 begins on 30 November 2026. It adds hazards such as excess cold and heat, falls, structural collapse, fire, explosions, electrical hazards and domestic hygiene. It does not yet apply to private renting.

Private landlords still have duties under the Homes (Fitness for Human Habitation) Act 2018 for tenancies under seven years, and the Housing Health and Safety Rating System lists damp and mould as hazard 1. Premises prejudicial to health can be a statutory nuisance.

Do councils treat damp?

Councils do not treat damp, but if you rent, your council's private sector housing team can inspect and order your landlord to act. Owners pay a private specialist. See council pest control for what councils do treat.

Mould and damp on walls

Black mould on walls is usually condensation on a cold external wall, not rising damp. Look at where it grows: corners, behind furniture and above windows point to condensation. A band low on the wall with a tide mark points to rising damp.

Wipe off the surface mould, then improve ventilation and heating. If it returns, or the plaster is salt-stained or crumbling, book an independent survey. Mould that follows rain suggests penetrating damp from gutters, pointing or render. Tenants should report it to the landlord in writing.

Damp and mould in the bathroom

Showers and baths put a lot of moisture into the air, so bathroom mould is mostly condensation. Use the extractor fan during and after a shower, keep the door shut while you shower and wipe wet surfaces.

If mould keeps coming back despite good ventilation, check for a leak behind the bath or basin, or in a pipe. A damp proof course will not cure it. Call a specialist if there is a persistent damp patch, soft plaster, or a stain that appears on the ceiling below.

Damp patches on the ceiling

A ceiling patch is usually water coming from above: a defective roof covering, a blocked gutter, or a leaking pipe or tank in the loft or bathroom above. Brown, spreading stains that grow after rain suggest the roof. Stains that stay the same in all weather suggest plumbing.

Find and stop the leak first, then let the area dry before repairs. If the ceiling sags, keep clear of it and get help quickly. A surveyor can trace the source. In social housing, ask the landlord to act within Awaab's Law timescales.

Damp in the bedroom

Breath, drying laundry on radiators and cold external walls make bedrooms prone to condensation. Mould often shows behind wardrobes and beds pushed against an outside wall, and around window reveals.

Leave a gap between furniture and the wall, ventilate in the morning and keep the room gently heated. Dry washing outdoors where you can. If the mould is spreading or comes with a musty smell despite this, ask a surveyor to check for penetrating damp. Tenants should report it to the landlord in writing.

Damp skirting boards

Rotting skirting, peeling paint and salt-stained plaster at the base of a wall are signs of rising damp. Ground raised above the damp proof course, or a failed course, are common causes.

A leaking pipe can look the same, so a survey should rule that out. Lower any soil or paving bridging the course, then get an independent opinion before paying for injection. If a tide mark and decayed timber floors appear together, call a PCA-qualified surveyor. Check the outside too: ground higher than the damp proof course, a leaking downpipe or a blocked air brick can all feed the damp.