The first question almost everyone asks when they call us is also the hardest to answer in one line: how much is this going to cost? Damp proofing prices vary enormously depending on what is actually wrong, how big the affected area is, and the type of property you own. A small patch of condensation mould might cost a couple of hundred pounds to put right, while waterproofing a damp basement flat in Kemptown can run into five figures. This guide sets out realistic 2026 figures for the Brighton and Sussex area so you can budget sensibly and, just as importantly, spot when a quote does not add up.
Pay for a diagnosis before any treatment
Before any numbers, one principle matters more than all of them: never pay for treatment before you have paid for a diagnosis. The single biggest way homeowners waste money on damp is by having an expensive remedy installed for a problem they never actually had. Most so-called rising damp turns out to be condensation, a leaking gutter, or bridged ground levels.
A proper damp survey costs a fraction of a treatment and frequently saves you the entire bill. Our surveys start from £95 plus VAT and the fee is credited against any remedial work we carry out, so a diagnosis is rarely money wasted.
Never pay for treatment before you have paid for a diagnosis — a survey costs a fraction of a remedy and often saves the whole bill.
If you want to know what that diagnosis actually covers, read What Does a Damp Survey Involve? before you book anything.
Indicative 2026 prices at a glance
As a broad guide for 2026, a typical damp proofing job in the South East falls somewhere between £800 and £3,000, with full rising damp treatment including replastering on a mid-terrace house more commonly landing in the £2,000 to £5,000 range. Condensation and mould work is usually cheaper, often £400 to £1,500 once ventilation is improved. Basement and cellar waterproofing is the most expensive category, frequently £6,000 to £15,000 or more for a full cavity drain membrane system with a sump and pump.
| Job type | Typical 2026 cost |
|---|---|
| Typical damp proofing job (South East) | £800 – £3,000 |
| Full rising damp treatment incl. replastering (mid-terrace) | £2,000 – £5,000 |
| Condensation and mould work | £400 – £1,500 |
| Basement / cellar waterproofing (full cavity drain system) | £6,000 – £15,000+ |
These are ballpark figures to set expectations, not a quote — the only way to know your number is a survey.
The cost of a chemical DPC, per metre
The most-searched single figure is the cost of a chemical damp-proof course, usually priced per linear metre of wall treated. In 2026 you should expect roughly £60 to £120 per linear metre for the injection itself across Sussex, with the wide range reflecting wall thickness, access, and whether internal or external injection is needed.
Crucially, that injection price almost never includes the work that makes the treatment actually last. When you read a very low per-metre figure, check what it excludes — it is usually the replastering, which is where most of the real cost sits.
| Item | Indicative cost |
|---|---|
| Chemical DPC injection | £60 – £120 per linear metre |
| Replastering a single affected wall | £200 – £800 |
| Positive input ventilation (PIV) unit, installed | £400 – £1,000 |
Replastering: the part homeowners underestimate
Replastering is the part homeowners consistently underestimate. After a chemical DPC is installed, the old contaminated plaster has to be hacked off and replaced with a salt-resistant render system, because the original plaster holds hygroscopic ground salts that will keep drawing moisture from the air for years if left in place.
Replastering a single affected wall typically costs £200 to £800 depending on size and finish, and doing a whole room can comfortably double the headline injection cost. Any quote that injects a DPC but leaves the old salt-laden plaster in place is setting you up to call someone back.
A DPC injection without the replastering is half a job — the salt-resistant render system is where most of a damp-proofing budget is actually spent.
The hidden extras to budget for
Then come the extras people forget to budget for. None of these are hidden charges from a reputable firm; they should all appear, itemised, on a proper written quote:
- Skip hire and waste removal for the old plaster and debris.
- Redecoration once the new plaster has fully dried.
- Scaffolding or access towers for penetrating damp repairs at high level.
- Fixing the original defect — a failed gutter, cracked render, or raised patio — that let the water in to begin with.
- Ventilation for condensation problems — a positive input ventilation unit usually costs around £400 to £1,000 installed and only a few pounds a year to run, while individual extractor fans are far cheaper.
Where damp has reached structural timber, allow for timber treatment as well — another reason a proper survey ahead of works matters.
Why Brighton and coastal Sussex cost more
Brighton and the Sussex coast genuinely do cost more than the national average, and it is worth understanding why so you can sense-check quotes:
- Much of the local housing stock is solid-wall Victorian and Edwardian, or older still in flint and bungaroosh, none of which behaves like a modern cavity wall and all of which needs more careful, more labour-intensive work.
- Basement and lower-ground flats are common along the seafront and in Kemptown, Brunswick and Hove, and below-ground waterproofing is inherently more involved than treating a ground-floor wall.
- Salt-laden coastal air and wind-driven rain accelerate the decay of render and pointing.
- Listed-building and conservation-area constraints across the city often rule out the cheapest modern fixes in favour of breathable lime repair.
A higher price here is frequently the correct price, not an inflated one.
How to avoid overpaying
So how do you avoid overpaying? Follow these steps:
- Insist on a diagnosis before a treatment, and be wary of any company offering a free survey whose report only ever recommends the one expensive product they happen to sell.
- Get the quote in writing and itemised, so you can see what the injection, the replastering, the access and the making-good each cost.
- Ask what guarantee is included and whether it is insurance-backed and transferable to a future owner.
- Ask whether the firm is genuinely qualified for your type of property.
We are a Biokil-approved contractor, our remedial work carries a 30-year guarantee, and we hold a 9.84 out of 10 rating across more than 440 verified Checkatrade reviews — but more than any of that, we will tell you in writing when you do not need the work at all.
If recurring mould is your concern rather than rising or penetrating damp, Black Mould on Walls explains why cleaning alone never holds and what the lasting fix actually costs.
Get a real number for your property
If you want a real number for your property rather than a national average, the only way to get one is to have the damp correctly diagnosed first. To arrange a survey anywhere in Brighton, Hove or the wider Sussex area, call us on 01273 536 985 or get in touch through our contact page. Surveys start from £95 plus VAT and are credited against any work you decide to go ahead with.
