The same discoloured wall can be caused by ground moisture, rainwater entry, a leak or humid indoor air. Pattern recognition is useful, but the building context decides the next step.
01
Start with position and timing
Rising moisture is usually considered at low level on ground-floor walls. Penetrating damp often changes with rainfall. Condensation tends to affect colder surfaces and may be seasonal. None of these clues is conclusive alone.
02
Look beyond the meter
Electrical moisture meters are useful comparative tools, but salts, metal and material density influence readings. External ground levels, gutters, ventilation, plumbing and wall construction provide essential context.
03
Choose a proportionate inspection
Photographs can support triage. Persistent, purchase-related or unclear problems deserve an on-site specialist inspection, with RICS or structural input where the concern is broader.
Technical review
Dan, Director / Surveyor
Last reviewed: July 2026. Advice is general until the property, access and visible evidence have been assessed.
When to arrange a visit
Book an inspection when the problem is persistent, changing, purchase-related or unclear after basic maintenance checks.