Damp proofing costs, and the half of the quote nobody shows you
The per-metre rate you are searching for is the smallest line on the bill. What the published guides say, where they disagree, and which parts of a damp quote get left out of the headline number.
By The Damp GuyLast updated
The short version
Injecting a chemical damp-proof course runs around £60 to £120 per linear metre, depending which published guide you read. That figure covers the drilling and the injection. Then comes the part that decides your bill: hacking off the old plaster and re-plastering, at £350 to £1,100 per wall, plus decoration, skirtings and the survey. One guide says outright that the survey, the plaster removal, the replastering, the decoration and any structural repair are usually extra. So the question to ask of a damp quote is not "is the rate fair". It is "what is not in it".
The published guides do not agree with each other
Two cost guides, both dated within six weeks of each other, both describing the same job.
| The job | MyJobQuote, 20 July 2026 | BestBuilders, August 2026 |
|---|---|---|
| Chemical DPC injection, per linear metre | £60 to £90 | £70 to £120 |
| Headline figure | £1,250 average overall | £1,500 to £4,000, whole house with re-plaster |
| Injection, installed, 3-bed semi | £650 to £950 | Not broken out by property type |
| Tanking slurry | £70 to £120 per m2 | £40 to £100 per m2 |
| Damp survey | Listed as usually extra, not priced | £150 to £600 depending on property size |
On tanking, the two ranges barely overlap. On injection, one guide's ceiling sits a third higher than the other's. Neither is wrong. They are compiled differently: one from quotes submitted by tradespeople on a lead-generation platform, the other stated as Q3 2026 contractor pricing from PCA-registered specialists.
Take the lesson from that. There is no national price for damp work, so treat any single confident number with suspicion. The ones above included. A range tells you whether your quote sits inside the normal band or somewhere odd. Ask nothing more of it.
Worth saying plainly: neither source is an independent consumer body. One is a trade cost reference. The other makes its money connecting you to a contractor. Both have an interest in the work happening. That does not make the figures useless. You should just know it about a number before you lean on it.
What is in the quote, and what is not
Check your quote against this list. It is why two quotes for the same job land thousands apart.
One guide sets it out directly. Typically included: the treatment application, the labour, standard materials and basic site clean-up. Usually extra: survey fees, plasterboard or render removal, replastering, painting and decoration, dehumidifying costs, and any structural repairs.
Look at what lands on that second list. Taking the old plaster off and putting new plaster back is not a finishing touch after a chemical damp-proof course. It is part of the job, because the old plaster usually carries the salts. And it can still sit outside the number you were quoted.
| The work after the treatment | Published range | Source |
|---|---|---|
| Hack off and re-plaster, one wall to about 1m | £350 to £700 | BestBuilders, Aug 2026 |
| Full-height re-plaster, one wall | £600 to £1,100 | BestBuilders, Aug 2026 |
| Replastering, per room | £450 to £800 | MyJobQuote, Jul 2026 |
| Painting and decorating, per room | £230 to £450 | MyJobQuote, Jul 2026 |
| Skirting board replacement, per room | £150 to £400 | MyJobQuote, Jul 2026 |
| Structural repairs | £500 to £3,000 and up | MyJobQuote, Jul 2026 |
Add up a single wall and the arithmetic is stark. The injection on a 5m wall, at the middle of the published range, is a couple of hundred pounds. The re-plastering on that same wall is £350 to £1,100.
The treatment everyone argues about is the cheap part.
Where else the number moves
Where you live. Published regional adjustments against the national average run from about +20% to +25% in inner London and +15% to +20% in the South East. They drop to -5% to -10% in the north and Scotland, and -5% to -15% in Wales and Northern Ireland. Labour is quoted at £150 to £250 per installer per day, higher in London and the South East.
Which treatment it is. The methods do not swap for each other, and neither do their prices. Installed totals are given as £650 to £3,400 for chemical DPC injection, £1,500 to £4,500 for a physical membrane system, and £2,800 to £6,700 for tanking slurry. A cellar is its own category: a typical 40m2 cellar comes out at £4,000 to £14,000, with cavity drain membrane and a sump and pump at £80 to £150 per m2.
The guarantee. An insurance-backed guarantee is priced at roughly 3% to 5% of the contract value. Know that, because it is a real line of cost. A guarantee from the contractor alone depends on that contractor still trading when you need it. Ask which of the two you are being offered.
The survey. Independent survey fees are published at £150 to £250 for a two-bed flat, £300 to £400 for a three-bed terrace or semi, and £450 to £600 for a four-bed detached. A free survey from the company quoting for the treatment costs you nothing, and it is not the same product.
Before you spend any of it
Every number above assumes the diagnosis is right. Test that assumption hardest, because you get none of this money back if the wrong thing was treated. A chemical damp-proof course does nothing for water coming through the wall from outside. It does nothing at all for condensation.
So the cheapest thing on this page is the reading you do first. Ask whether the damp was confirmed by the test the British Standard points to, or inferred from a meter reading that cannot settle it. Then ask whether anyone has ruled out a defect letting water in from outside.
A £300 independent survey that stops a £3,000 treatment for the wrong problem is the best money on this page.
What to ask before you accept the quote
The number at the bottom is the part you keep staring at. Ask about the parts that are not on the page.
- Does this include hacking off and re-plastering? On the published lists it usually does not, and it is often the larger half.
- What is excluded entirely? Ask for it as a list. Survey, plaster removal, decoration, skirtings, dehumidifying and structural repair are the usual answers.
- How many linear metres, and at what rate? A total with no metreage behind it compares with nothing.
- Is the guarantee insurance-backed or yours alone? The insurance-backed version is priced at about 3% to 5% of the contract. If you are paying for it, you should see it on the quote.
- What happens to the price if the cause turns out to be something else? Worth asking before the plaster comes off, not after.
About this resource
Every figure here comes from one of two published guides, named and dated beside it. MyJobQuote, last updated 20 July 2026, states its basis as real quotes from tradespeople on its platform. BestBuilders, dated August 2026, states its basis as Q3 2026 contractor pricing from PCA-registered specialists. Neither is an independent consumer body, and both have a commercial interest in the work being done. Two other widely cited guides were not usable, so they are not cited.
None of these numbers is a quote for your job, and prices move. This site does not survey, treat or quote for work, and takes no fee from anyone doing it. Use the ranges to judge whether your quote sits in the normal band, and to ask what has been left out of it.
Common questions
How much should damp proofing cost?
There is no national price, and the two published guides read for this page disagree materially on the same job. Use them as a band, not a benchmark: if your quote sits inside the ranges above you have learned that it is ordinary, and if it sits well outside them you have a question to ask. What you cannot do is take any single confident figure, including the ones here, as the price of your job.
Is damp proofing worth it?
Only if the diagnosis is right, and that is not a hedge. A chemical damp proof course does nothing for water coming through the wall from outside, and nothing at all for condensation. So the question is not whether the price is fair. It is whether anyone has established that the moisture is rising, using evidence from inside the wall rather than a reading off the surface of the plaster.
Can I damp proof my house myself?
Injection kits are sold to anyone, so the physical job is not what stops you. Two other things do. The first is that you would be treating a diagnosis nobody has confirmed, which is how the money gets wasted whoever holds the drill. The second is the making-good: hacking off salted plaster and re-plastering is the larger half of most quotes, and it is skilled work with a specific material specification.
What is better than a chemical damp proof course?
It depends entirely on what is wrong, which is the honest answer and also the useful one. If the course is bridged by paving, render or a raised border, then dealing with the ground level is the repair and injecting the wall is not. If water is crossing from outside, the fix is the defect letting it in. A chemical course is the right answer to exactly one problem, and it is the one that is hardest to confirm.
How much does damp damage the value of a house?
No figure is given here, because nothing was found that would survive being checked. What can be said is what actually happens in a sale. A survey flagging damp turns into a retention or a renegotiation, and the size of it usually tracks the quote the buyer is holding rather than any independent view of the problem. Which makes an independent opinion on that quote worth more than a percentage would be.