Cost of Damp Proofing in the UK (2025)
Damp proofing costs vary widely: chemical DPC injection costs £70–£300 per metre. Full basement waterproofing runs £5,000–£20,000. Always get an independent survey first.
The importance of an independent survey
Damp treatment companies that offer free surveys have a commercial interest in finding damp that needs treating. Rising damp is often misdiagnosed — the cause may be condensation, bridged cavity walls, or leaking gutters, all of which have much cheaper solutions than chemical DPC injection. Always get an independent survey from a surveyor or specialist who is not selling the treatment.
Rising damp vs condensation vs penetrating damp
Rising damp appears as a tide mark on lower walls, typically below 1 metre, with white salt deposits. Condensation appears on cold surfaces (windows, exterior walls) and produces black mould — it is caused by inadequate ventilation and is not a structural problem. Penetrating damp follows rain and usually traces back to a specific external defect (cracked render, blocked gutter, failed flashing). Each has a different solution at a very different price.
Cost Breakdown
All prices are indicative UK averages for 2025. Actual costs vary by location, specification, and contractor. London and South East rates are typically 20–35% higher.
| Item | Low | High |
|---|---|---|
| Chemical DPC injection (per metre) | £70 | £150 |
| Replastering after DPC treatment (per m²) | £35 | £60 |
| Basement tanking (per m²) | £70 | £120 |
| Cavity drain membrane (per m²) | £60 | £100 |
| Penetrating damp repair | £200 | £800 |
| Independent damp survey | £200 | £500 |
What Affects the Cost?
- ✓Type of damp — rising, penetrating, or condensation
- ✓Extent of affected area
- ✓Whether replastering is included
- ✓Basement size and waterproofing method chosen
- ✓Access to affected areas
- ✓Quality of materials and guarantee offered
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Post a Job — It's FreeFrequently Asked Questions
Should I get a free damp survey?
Be cautious — free surveys from treatment companies often lead to oversold solutions. Consider paying £200–£500 for an independent survey from a RICS surveyor or PCA-qualified independent specialist. This frequently saves thousands.
Does damp proofing come with a guarantee?
Reputable companies offer 20–30 year guarantees on chemical DPC treatment and associated replastering. Ensure the guarantee is backed by an insurance-backed warranty scheme so it remains valid if the company ceases trading.
Will damp proofing increase my house value?
Unresolved damp reduces value significantly — often by more than the cost of treatment. Resolving the issue and having a guarantee in place removes a major barrier to mortgage approval and buyer confidence.
What causes condensation damp and how do I fix it?
Condensation is caused by moisture in the air meeting cold surfaces. Solutions include improved ventilation (extractor fans in kitchens and bathrooms), positive input ventilation (PIV) units, and better heating. It does not require chemical treatment.