Basement waterproofing and tanking cost
Here is a plain-English summary of what published UK cost guides say about basement and cellar waterproofing in 2026. Treat the figures as indicative only: your property may cost more or less.
Indicative cost ranges
| Item | Indicative cost (2026) |
|---|---|
| Cementitious tanking (Type A) | about £40 – £120 per m² |
| Cavity drain membrane system (Type C) | about £80 – £200 per m² |
| External waterproofing (excavation) | about £100 – £200 per m² |
| Sump pump installation | about £500 – £2,000 |
What affects the price
- Total wall and floor area to be treated
- Condition of the masonry and how much preparation is needed
- Amount of water and whether a sump and pump are required
- Access to the cellar and removal of waste
- Whether the space will be habitable, which usually means a higher specification
- Guarantees and any insurance backing
Which system do I need?
Read our guides to tanking and cavity drain membranes, or start with basement waterproofing. A specialist survey is the only reliable way to choose.
Indicative ranges drawn from published UK 2026 cost guides (Checkatrade, MyBuilder, ResiQuote, BestBuilders), accessed 21 October 2026. They are not quotes and are not BasementBridge prices. Your specialist will price your property after a survey.