Survey finding
Cellar damp on your survey: what to do
UK cellars are nearly always damp. This page covers the difference between manageable and problem damp.
Last updated: .
Finding
Cellar / basement damp
What this usually means
UK cellars are nearly always damp to some degree because they sit below water table or are surrounded by saturated ground. Whether it's a problem depends on use: storage cellars tolerate it; converted living spaces need tanking or cavity drain membrane systems.
Why it matters
Tanking failure or unaddressed damp in habitable cellar conversions is a category 3 finding that can affect both habitability and lender appetite.
Ask your surveyor
- Check:Is the cellar in use as habitable space, and does it meet building regulations?
- Check:What is the existing waterproofing system and is it functioning?
Ask the seller
- Check:When was the waterproofing system installed and by whom?
- Check:Is there a maintenance schedule for the pumps?
Next steps
- •Get two written quotes from local trades before negotiating with the seller.
- •Speak to your mortgage broker before exchanging if the finding affects mortgageability.
Tool shortcut
Check the property before you offer
Free preview: flood risk, EPC rating, crime, tenure and air quality. The £9.99 report adds the remaining 17 checks, 22 in all, drawing on up to 15 public datasets.
Run a free previewDamp risk often tracks EPC band and building age. The full report checks both.
What you need to know
Severity
Significant. Specialist follow-up usually warranted before exchange.
Typical cost to fix
Cementitious tanking £100-£200/m². Cavity drain membrane (CDM) system with sump and pump £150-£300/m² (typical 30m² cellar £4,500-£9,000). Periodic pump and damp-proofing maintenance £200-£500/year.
Mortgage impact
Lender may exclude habitable use if damp is severe; usually lend on the rest of the property.
Insurance impact
Cellar contents are commonly excluded or limited.
When to pull out
Pull out only if cellar habitability was material to the purchase price.
When to renegotiate, and by how much
Cost of remediation if you intend habitable use; typical 1-3% off purchase price.
Thinking of pulling out or renegotiating? What to do after a bad survey
Run the check on this address
The Survey Decoder explains the wording. The full report adds address-specific flood, subsidence, EPC, crime, listed status, building age and price comparison data, so a single finding isn't judged in isolation.
Run the check
Check the property before you offer
Free preview: flood risk, EPC rating, crime, tenure and air quality. The £9.99 report adds the remaining 17 checks, 22 in all, drawing on up to 15 public datasets.
Run a free previewRead next
House survey cost UK , what a Level 2 and a Level 3 actually cost in 2026, and Level 2 vs Level 3 , what each level does and does not cover. Not every finding here is something a surveyor assesses — some are a conveyancer's search — and the comparison says which is which.
How MyPropertyScan produces this guide, and what it is not
Published by MyPropertyScan and written by Ziad Nasr, who is accountable for its accuracy. No page here is written or reviewed by a chartered surveyor, conveyancer or regulated adviser, and we do not claim otherwise.
This page is not:
- Chartered surveying: we do not inspect properties or produce RICS Home Survey reports
- Legal advice: we do not act as conveyancers or advise on title, tenure or contracts
- Mortgage or insurance advice: we are not regulated by the FCA and give no recommendations
Figures and process steps come from the published UK datasets and standards listed on this page, not from professional practice. Pages are updated when source coverage, survey cost assumptions, or lender and legal requirements materially change. Dataset limitations are set out on the methodology page.
Spotted something out of date or wrong? Email [email protected] and we will correct it and change the update date.
Sources used
We use UK public and specialist sources where they are available. Public datasets can be incomplete, delayed, or missing for some addresses. Treat them as a starting point, not as a replacement for professional advice.
Source standard: preference goes to official government datasets, statutory bodies, professional standards, and primary dataset publishers. We cite the source family on the page and explain coverage limits rather than filling gaps with unsupported estimates.
- Professional standard: RICS Home Survey StandardRICS standard for condition-based residential surveys in the UK.
- Learn more from: RICS consumer guide to surveysConsumer-facing guide to survey types and when each level is appropriate.
- Official guidance: GOV.UK buying or selling your homeGovernment overview of the home buying and selling process.