Damp proofing cost: prices by treatment in 2026
2026 prices for every damp treatment: injected damp proof courses and replastering, penetrating damp repairs, condensation fixes, cellar tanking and the survey that comes first.
Damp proofing costs from £30 a room for anti-mould paint to £7,500 for a physical damp proof course, and the type of damp decides where you land. An injected damp course runs £60 to £150 per metre of wall, and the replastering after it is often the bigger bill. We give 2026 prices by treatment, a one-wall worked example, what a survey costs, and the checks to make before paying for injection.
Damp proofing cost by treatment
These are 2026 prices for the work itself. The type of damp decides which lines apply, so a survey should name it before anyone prices a treatment. Where a range is known to exclude VAT, the table says so. For the rest, ask whether the quote includes it.
| Treatment | Price | What the price covers |
|---|---|---|
| Independent damp survey | £150 – £600 | A visit and written report from someone not selling the treatment |
| Injected damp proof course | £60 – £150 per metre | Chemical injection along the base of the wall, before replastering |
| Injected damp proof course, whole house | £1,000 – £3,000 | Excluding VAT, with replastering on top |
| Replastering after a damp proof course | £450 – £800 per room | Stripping salt-contaminated plaster and replastering |
| Physical damp proof course retrofit | £2,500 – £7,500 | A new physical course built into the wall, excluding VAT |
| Repointing brickwork | £40 – £80 per m² | Replacing failed mortar joints |
| Masonry repairs | £300 – £1,500 | Cracked render, failed pointing or damaged brickwork letting rain in |
| External waterproof coating | £15 – £30 per m² | A coating on the outside face of the wall |
| Gutter or outlet repair | £80 – £220 | Clearing blockages and reseating joints |
| Anti-mould paint | £30 – £70 per room | A mould control coating after cleaning |
| Ventilation upgrade | £200 – £600 | Better extraction or background ventilation |
| Dehumidifier | £100 – £300 | A unit you buy and run yourself |
| Cellar tanking (Type A) | £100 – £200 per m² | An applied barrier on walls and floor, excluding VAT |
| Drained cavity membrane (Type C) | £80 – £150 per m² | A membrane draining water to a sump, excluding VAT |
| Sump and pump | £1,500 – £4,000 | For a Type C system, excluding VAT |
Types of damp and what each costs to fix
Damp in a home comes from four places: condensation, rain getting in through a defect (penetrating damp), ground water drawn up the wall (rising damp), and leaks from pipes, baths and sinks. Each has its own fix and its own bill, and only one of them is treated with a damp proof course.
| Type | What it looks like | Where and when | Usual fix and cost |
|---|---|---|---|
| Condensation | Black mould spotting and water on window glass | Corners, behind furniture, window reveals and cold outside walls; worse in winter and after showers or cooking | Ventilation and steady heat, from £30 a room |
| Penetrating damp | A defined patch that grows after rain and dries out between | Any height, below a defect in a wall, roof, gutter or window | Repair the defect, £80 – £1,500 |
| Rising damp | A tide mark with white salts on the surface | Ground-floor walls, up to about 1 metre high, all year round | Damp proof course and replastering, £60 – £150 per metre plus plaster |
| Leak | Damp spreading from a pipe run, bath or sink | Next to waste and heating pipes, baths and sinks | A plumbing repair, then drying out |
Damp proof course cost
Injected damp proof course cost
Rising damp is ground water drawn up through the masonry. It leaves a tide mark up to about a metre from the floor, with salts on the surface where the water evaporates. The usual treatment is a chemical damp proof course injected along the bottom of the wall.
Injection costs £60 to £150 per linear metre in 2026. A whole house comes to £1,000 to £3,000 excluding VAT, before any replastering. Because the price runs by the metre, measure the wall yourself and check the metres on the quote against it.
Replastering after a damp course
Replastering is usually needed and often costs more than the injection. Plaster on a wall that has been damp holds salts, and those salts keep drawing moisture out of the air long after the wall itself has dried. Stripping and replastering costs £450 to £800 per room.
The plaster itself costs more than usual. Damp-proof renovating plaster runs £18 to £28 a 25kg bag, against £8 to £11 for the finishing plaster used when plastering a room in the ordinary way.
Physical damp proof course cost
A physical damp proof course, a new barrier retrofitted into the wall rather than a chemical injected into it, costs £2,500 to £7,500 excluding VAT. It is the dearest way to stop rising damp, and it still leaves the replastering to pay for.
Check the damp course you already have
In England, Approved Document C sets the damp proof course in an outside wall at least 150mm above the adjoining ground. Wales, Scotland and Northern Ireland publish their own standards. Where a patio, path or flower bed has been built up to that line, wet ground sits against the wall above the course, and no injection helps until the ground comes back down.
Penetrating damp repair cost
Penetrating damp is rain getting through a defect in a wall, roof, window or floor. It shows as a defined patch that gets worse after rain and dries out between. The fix is the defect, not a damp course.
Most of these repairs are small jobs. Clearing and reseating a gutter costs £80 to £220, and a minor roof repair such as a replaced tile or a resealed gutter joint costs £150 to £400. Repointing failed mortar costs £40 to £80 per m², and masonry repairs to cracked render or damaged brickwork run £300 to £1,500.
The expensive case is a wall that needs a full re-render with treatment inside, at £2,000 to £5,000. An external waterproof coating costs £15 to £30 per m² and protects the wall for 10 to 15 years.
After the repair, let the wall dry before replastering. On a thick solid wall that takes months rather than weeks, and new plaster put on a wall that is still damp tends to come off again.
Condensation treatment cost
Condensation is warm, moist air meeting a cold surface. It is the most common type of damp and the cheapest to fix, because it needs ventilation and heat rather than building work, and stopping condensation starts with habits that cost nothing: lids on pans, laundry dried outside, windows opened for 20 minutes a day.
Where habits are not enough, anti-mould paint costs £30 to £70 a room, a dehumidifier £100 to £300, and a ventilation upgrade such as better extraction £200 to £600. An extractor fan has to vent outside, not into the loft.
Cleaning and painting on their own do not stop black mould coming back. The moisture behind it has to be dealt with too, or the spots return through the new coat.
Cellar and basement tanking cost
Below ground, water is pushed against the wall under pressure, and the design matters more than the product. Waterproofing below ground falls into three types under BS 8102. Type A is an applied barrier or membrane, which is what most people mean by tanking. Type B relies on a watertight reinforced concrete structure. Type C is a drained cavity: an internal membrane lets water through to a perimeter drain and a sump pump.
Tanking costs £100 to £200 per m² excluding VAT. A Type C membrane costs £80 to £150 per m², plus £1,500 to £4,000 for the sump and pump. Most existing cellars end up Type C or a mix of the two, because a barrier alone has to hold back the full water pressure with no margin for a single defect.
Tanking also turns up above ground. In a bathroom refit, damp treatment or tanking behind a tiled shower adds £1,200 to £3,100 including VAT.
Damp survey cost
An independent damp survey costs £150 to £600 in 2026. That is the one line worth paying for before any other, because it decides which of the treatments above you need.
Free surveys are common, but they usually come from firms that also sell the treatment. The handheld meters used on most inspections are only reliable on timber. Pressed against plaster, they read the salts in the wall as well as any water, so a meter alone can make a dry wall look damp.
Damp surveyor is not a protected title, and the work is not statutorily regulated. Ask whoever surveys the house whether they or their firm will quote for the treatment. A free survey that recommends injection without naming where the water comes from is a reason to get a second opinion from someone with nothing to sell.
Damp in older solid-wall houses
Solid walls have no cavity and often no damp proof course. They take in moisture and let it out again, and they rely on being able to breathe, which is why lime plaster, lime mortar and permeable paint suit them.
Cement render, gypsum plaster and modern masonry paint seal that wall, and the moisture has nowhere to go. The fix there is taking off what traps the water, improving drainage and ventilation round the house, and letting the wall dry. Listed and heritage homes may need lime-based mortars, and a quote for one should name them.
In a renovation of an older house, the damp work comes before the new plaster and decoration, so the walls have time to dry before anything goes back on them.
What damp costs if you leave it
Damp left alone spreads the bill into other trades. Wet timber rots, damp masonry can move, mould affects the air in the home, redecorating has to be repeated, and a survey that finds unresolved damp gives a buyer a reason to offer less.
Timber is the expensive one. Dry rot starts once wood holds around 20% moisture, and dry rot treatment costs £300 to £3,000 on top of a £150 to £400 survey. Damp wood also attracts wood-boring beetles, so a joist that has sat wet for years can need woodworm treatment as well as drying out.
What makes one damp quote dearer than another
Labour and access make up a large share of any damp bill. When two quotes for the same wall differ, the gap usually traces to one of these:
- Type of damp. Condensation costs least to treat, penetrating damp sits in the middle, and rising damp with replastering costs most.
- How much plaster comes off. Salt-contaminated plaster has to go, and every room stripped adds £450 to £800.
- Wall type. Solid Victorian walls may need breathable systems, cavity walls carry moisture differently, and listed buildings may need lime mortar.
- Access. Scaffolding, or digging out ground along an outside wall, adds labour that a per-metre price does not include.
- Salts. Heavy salt contamination means more plaster off and a renovating plaster going back on.
- VAT. Some firms quote excluding VAT and some including it, so put every quote on the same basis before comparing.
- Location. Labour rates follow the postcode. London labour runs well above the UK median, so damp proofing in London prices higher in each range than the same job in Leeds or Liverpool.
How long damp proofing lasts
An injected damp proof course can last 20 years or more, and an external waterproof coating 10 to 15 years. A Type C cellar system needs its pump serviced for the life of the building.
Long guarantees are common and worth less than they look. An insurance-backed guarantee only honours the terms of the original guarantee, and it typically pays out only where the contractor has ceased trading as the policy defines it. Ask who underwrites it and what triggers a claim.
Grants and who pays for damp proofing
The Energy Company Obligation funds insulation, such as loft or cavity wall insulation, and heating upgrades for households on qualifying benefits, in homes rated D to G on their EPC (E to G for private renters). Damp proofing is not one of the measures it lists.
ECO4 runs in England, Scotland and Wales until 31 December 2026, and Northern Ireland sits outside it. Insulation and steadier heating help with condensation, but they do nothing for rain getting in or rising damp.
In England and Wales, a landlord has to fix the cause of damp and mould in a rented home. Social landlords in England must investigate serious damp and mould within 10 working days under Awaab's Law, in force since October 2025. In Wales, damp and mould is the first of 29 matters that can make a home unfit under the Renting Homes (Wales) Act 2016, and the landlord cannot ask the tenant to fix a problem that is not the tenant's fault.
Common questions
How much does a damp proof course cost per metre?
An injected damp proof course costs £60 to £150 per linear metre in 2026. That covers the injection only. Replastering the room afterwards adds £450 to £800, and it is often the larger part of the bill because the old plaster holds salts.
How much does it cost to damp proof a whole house?
Injecting a damp proof course through a whole house costs £1,000 to £3,000 excluding VAT, before replastering. Larger footprints, and jobs that add a membrane, reach £2,000 to £5,000. A physical damp proof course retrofit costs £2,500 to £7,500 excluding VAT.
How much does a damp survey cost?
An independent damp survey costs £150 to £600 in 2026. Free surveys are widely offered, but usually by firms that also sell the treatment. A survey from someone with nothing to sell is worth paying for when the fix on the table is a £1,000 to £3,000 injection.
Can I damp proof my house myself?
Condensation is largely a DIY job, and small, clearly diagnosed damp patches can be treated with DIY products. Rising damp, widespread damp and water coming in below ground need specialist work, because the design has to be right rather than the product. Penetrating damp depends on the defect, and clearing a blocked gutter is often enough.
How many years does a damp proof course last?
An injected damp proof course can last 20 years or more. External waterproof coatings last 10 to 15 years, and a drained cellar system needs its pump serviced for the life of the building. A long guarantee only helps once you know who underwrites it and what triggers a payout.
Are there government grants for damp proofing?
Damp proofing is not among the measures the Energy Company Obligation funds. ECO pays for insulation and heating upgrades for households on qualifying benefits in homes rated D to G on their EPC. Tenants in England and Wales can go to the landlord, who has to fix the cause of damp and mould.
Does home insurance cover damp?
Standard home insurance does not usually cover damp caused by gradual deterioration, condensation or poor maintenance. Rising damp is rarely covered unless it follows directly from an insured event. Read the policy wording before counting on a claim to pay for the survey or the treatment.
Can you sell a house with damp?
A house with damp can be sold, and the damp more often becomes a negotiating point than a reason a mortgage is refused. What matters to a lender is whether the cause has been found and can be repaired, so a survey and a quote help the sale. In Scotland, the seller's Home Report includes a survey of the home's condition and repairs.