Damp
What can a home survey say about a cellar?
A cellar or basement in a home survey is only as known as the parts the surveyor could enter. The report can describe damp, timber and access. It does not prove a tanking system, test a pump, or decide that the space is a lawful bedroom. If the door stayed shut, the honest mark is not inspected.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless a source says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What can the surveyor say about a cellar they actually entered?
They can describe what was in reach: the walls, the floor, the stair, any stain, mould, soft skirting, or standing water, and the parts still hidden by storage. A RICS home survey is visual. It does not core the walls, lift a cemented floor, or run a moisture survey that names one cause. The paragraph should separate what was seen from what is only a possibility.
Level 1 is a more limited overview than Level 3, and neither level turns a cellar into a waterproofing design. If headroom, a low beam or stored goods stopped the surveyor, the report should say so. A photograph of the door is not a tour of the room.
Why is a waterproof coating not the same as a dry cellar?
A coating, a plastic membrane or a band of tanking slurry shows that someone tried to keep water out, or to hide a stain. It does not show that the attempt worked, that it covers the whole wall, or that it will still work after you store furniture against it. The survey records the finish it could see. It does not honour a guarantee that was not in the file.
Below-ground walls often take moisture from the ground beside them. Some old cellars were built to breathe, and a hard coating can push damp higher or trap it in the plaster. If you need the room dry for living, that is a design question for someone who will specify the system, after the survey has said what is wet now.
What should you separate: the cellar fabric, any pump, and how you hope to use the room?
Condition is whether the fabric looks wet, decayed or incomplete. A pump in the corner is a machine the survey did not switch on and did not service. How you hope to use the room, as a store, a gym or a bedroom, is a plan. Building regulations, fire escape and a lease, where there is one, decide the lawful use. The survey does not issue those approvals.
- Ask which parts of the cellar were entered and which were blocked.
- Ask what was wet, and what was only hidden.
- Ask the solicitor, not the surveyor, whether a bedroom use is supported by the papers.
Common questions
If a cellar smells damp from the doorway but the surveyor did not go down, what should the report say?
It should say the cellar was not inspected, and it may mention the smell as a limit rather than as a diagnosis. A smell at the door is not a tour of the walls, not a timber check, and not a rating of the floor. Ask for access before you exchange if you need those surfaces seen. Do not upgrade a doorway impression into a damp-proofing price.
Does a stain on a cellar ceiling mean the ground-floor joists have rising damp?
No. A ceiling stain under the ground floor can be a spilled bathroom, a leaking pipe, or condensation on a cold soffit. Rising damp is moisture from the ground in the walls, usually low down. The survey should say which surface was stained. Do not buy a chemical damp-proof course for the room above because the cellar ceiling looks marked.
Does a fitted wine rack mean the cellar was waterproofed?
No. Joinery shows that someone used the room. It does not show a membrane, a drained cavity or a guarantee. Bottles and racks can sit against a wall that is still damp. Ask what covering, if any, the surveyor could see on the masonry behind the rack. If they could not see it, that wall is still unseen.
What should you ask if the cellar stair is new but the walls look much older?
Ask the surveyor to describe the stair and the walls as separate elements, and ask your solicitor for any building-regulations paperwork for the stair or a lowered floor. A new flight does not prove the retaining walls were rebuilt, and old walls do not prove the stair is inadequate. The survey does not sign the work off.
Does a dry cellar on an August inspection mean it stays dry in January?
No. The report is the day of the visit. A dry summer does not measure groundwater later in the year, and a wet January is not automatically rising damp either. If the use you want cannot tolerate seasonal damp, say so and get a design, not a second guess from the same dry-day paragraph.
Should you expect the surveyor to unpack a cellar full of the seller’s boxes?
No. Stored goods are the seller’s. The survey records the limit. If you need the perimeter walls seen, ask the agent for the boxes to be moved before the inspection, or accept a not-inspected note and decide whether that gap matters before you exchange. Do not move someone else’s stored goods on a viewing.
Can the survey clear a cellar for conversion to a bedroom after you buy?
No. A home survey is not a conversion design, not a fire-escape check, and not building-regulations approval. It can warn you about damp, low headroom, a single stair, or timber it could see. The design, the consents and the cost come later, from people instructed to do that work. There is no RICS price for a cellar conversion on this page.
Sources
Key facts
- Entered or not
- If the surveyor did not go in, the cellar is not inspected. That is not a condition rating 1.
- What they can record
- Staining, mould, soft timber, the stair, standing water, and limits. A visual survey does not open the floor slab.
- Coatings
- Paint, slurry or a membrane seen on the day is not a guarantee the room stays dry, and not a design for a conversion.
- Use of the room
- A bed, a wine rack or a new stair does not make the space a lawful bedroom. Building regulations and the lease, if any, are not the survey.