Damp meter for walls: what a high number can mean
Updated: October 2026
The stain is above the skirting, the room smells slightly musty, and someone has already told you the wall has rising damp because a meter beeped. A damp meter for walls can map wetter and drier spots on the same surface. It cannot name the source of the water, and it cannot justify injection on its own. Products Compared read the twelve amazon.co.uk moisture meters on 16 October 2026 and the public UK guidance below. We did not survey your house. The product grid is the [moisture meter comparison](/hub/measuring-equipment/moisture-meter).
The stain is above the skirting, the room smells slightly musty, and someone has already told you the wall has rising damp because a meter beeped.
The stain is above the skirting, the room smells slightly musty, and someone has already told you the wall has rising damp because a meter beeped. A damp meter for walls can map wetter and drier spots on the same surface. It cannot name the source of the water, and it cannot justify injection on its own. Products Compared read the twelve amazon.co.uk moisture meters on 16 October 2026 and the public UK guidance below. We did not survey your house. The product grid is the moisture meter comparison.
Our top picks
| Badge | Product | Sensor | Building scale | Surface | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  RDINSCOS RDINSCOS MT19 | Pin | Named, no band | Pins mark it | 9.2 | about £20.99 | View offer |
| Preis-Tipp |  COCZOW COCZOW PM6811A | Pin | 1.5–30% | Pins mark it | 9.0 | about £17.99 | View offer |
| Alternative |  Mecurate Mecurate pinless PDM-01 | Pinless | Reference only | No pinholes | 9.0 | about £24.99 | View offer |
On this page
A wall meter maps a pattern
A pin meter pushes two probes into the surface and reads how easily electricity passes. A pinless meter sits a pad on the paint and reads a capacitance change. Both can show that one patch differs from another. Neither weighs the water in the wall. The Property Care Association's code treats electrical readings in masonry as qualitative and comparative. Salts affect them. The meter does not separate rising damp, penetrating rain and condensation. The button sequence is on the how to use a moisture meter page.
Why a high number is not rising damp
A high reading on a dry-feeling wall is a common result when hygroscopic salts are in the plaster. The Property Care Association says an electrical check of a new damp-proof course is unsatisfactory for that reason: the salts remain, so the meter can still shout. SPAB says true rising damp is often misdiagnosed from the meter. Historic England's HEAG311 says a few high readings do not justify costly invasive work. RICS tells consumers to be wary of a diagnosis that uses only a damp meter on hard walls. The 20% figure you may have seen is a firewood rule in England, and it does not belong on plaster.
How to compare two spots
Use the same mode, the same finish and the same pressure. Start on a part of the wall that looks dry, away from radiators, foil-backed board and metal beads. Then read the stain. Write both numbers, the mode and the height above the floor. One photo of a red LED is not a profile. Do not compare a pin reading with a pinless reading as if they were the same scale. The pattern can support leaving a wetter corner unpainted. It cannot support a decision to inject because the meter beeped.
Which meters in this set claim walls
Dryzone prints building materials at 0–40%. COCZOW prints building materials at 1.5–30%. RDINSCOS names a building mode and does not print a numeric building range. If the paint must stay intact, the pinless pair is the relevant shelf. Mecurate says building-material percentages are for reference only. Neoteck calls wall 0–20% and masonry 0–33% relative, and claims ±4% on wood modes only. Who should buy which shape is on the best moisture meter page. A qualifying purchase through our links can earn a commission at no extra cost to you.
When a surveyor should take over
Stop when the patch returns after the leak, the gutter or the blocked air brick has been dealt with. Stop when you are buying or selling, or when mould is widespread. HomeOwners Alliance states that a standalone damp survey often costs £200–£600, and that figure is theirs, not a quote from us. You should not use it to choose chemical injection.
Common questions
What percent means the wall is damp?
There is no single UK percent that means a masonry wall is damp. Compare the stain with a dry-looking area of the same finish, on the same mode. Mecurate tells you building percentages are reference only. Neoteck calls wall and masonry relative. Dryzone's building scale runs 0–40% as a listed range, and Safeguard still describes masonry values as indicative. A number that is clearly higher than your reference is a reason to investigate. It is not a diagnosis.
Can the meter tell rising damp from condensation?
No. The Property Care Association says electrical meters in masonry cannot separate sources. Condensation, rain penetration and a ground-moisture problem can all leave a high spot. A tide mark, the season, the ventilation and the outside ground level are part of the picture, which is SPAB's point. The meter only shows a difference in electrical behaviour. Naming the cause is a survey, not a mode button.
Is plaster ready to paint when the meter drops?
A drop against your own earlier readings, on the same mode and the same spots, is a useful sign that the surface is drying. It is not a manufacturer's paint specification. If the number falls and then sticks well above the dry reference, salts or a remaining leak are still in play. Follow the paint maker's instructions for the product you are about to open. Do not treat a green LED as a guarantee the emulsion will hold.
When should I pay for a survey?
Pay when damp keeps returning, when a purchase or a dispute needs a signed opinion, or when mould is widespread. HomeOwners Alliance's published range for a standalone damp survey is often £200–£600. That is their figure. Ask, as RICS suggests, what the inspection covers, and be wary of a visit that only waves a meter at a hard wall and then sells a treatment. A household meter is still fine for watching a known wet patch dry.
Will a new damp-proof course show as dry straight away?
Do not expect it to. The Property Care Association says an electrical check is unsatisfactory after a new damp-proof course because salts remain in the masonry and can keep readings high. A lower number later, against your own profile, is more informative than a single hope of a dry wall on day one. If someone promises the meter will prove the injection overnight, that promise is larger than the instrument.
Related pages
Sources
Public UK sources on timber moisture, Ready to Burn in England, and damp readings in buildings. Prices, stars, and review counts are the amazon.co.uk listing figures in this set. Prices move. There was no laboratory test and no oven-dry calibration. Last checked 16 October 2026.
- GOV.UK, selling wood for domestic use in England (retrieved 16 October 2026)
- SI 2020/1095, domestic solid fuels standards in England (retrieved 16 October 2026)
- Property Care Association, code of practice for dampness in buildings (January 2023) (retrieved 16 October 2026)
- Property Care Association, use of moisture meters to diagnose dampness (retrieved 16 October 2026)
- BS EN 13183-2:2002, moisture content of sawn timber by electrical resistance (retrieved 16 October 2026)
- BS 5250:2021, management of moisture in buildings (retrieved 16 October 2026)
- Approved Document C, resistance to contaminants and moisture (retrieved 16 October 2026)
- Forest Research, a simple method for testing moisture content (retrieved 16 October 2026)