Condensation forms when indoor moisture reaches a surface cold enough for water vapour to condense. Use the checker and guides below to narrow the likely cause.
Why windows get wet and when the pattern may point to something else.
Check this pattern →Use the location and surface conditions to check whether condensation is plausible.
Check this pattern →Compare cold-surface condensation with rain penetration or a leak.
Check this pattern →Compare condensation clues with suspected rising damp before paying for treatment.
Check this pattern →Condensation is one possible cause of damp in UK homes. It depends on the moisture in the air, room temperature, surface temperature and ventilation, while persistent damp can also come from leaks, rain penetration, ground moisture or more than one source. Use the decision tool and symptom guides to gather evidence before choosing a fix.
Damp behind a wardrobe can fit a condensation pattern because furniture can restrict air movement beside a cold surface, but the location alone does not prove the cause. Check the moisture pattern, room conditions and affected surface before deciding what to fix.
Read guide →Window condensation forms when moist indoor air cools against glass or frames that are cold enough for water vapour to condense. The fix is not one universal trick: reduce moisture, improve ventilation and address unusually cold surfaces or building defects where needed.
Read guide →For many UK homes, around 40–60% relative humidity is a useful practical operating range, but there is no single humidity number that guarantees a home will be mould-free. Condensation risk depends on temperature, cold surfaces, ventilation and how much moisture is being produced.
Read guide →Condensation comes from indoor moisture settling on cold surfaces. Penetrating damp is water entering through a defect in the building fabric or a leak. The pattern and timing help narrow the cause.
Read guide →Condensation and rising damp can both leave wet walls, but they come from different moisture sources. The location and pattern are clues, not a substitute for investigation when the cause is uncertain.
Read guide →Mould behind a wardrobe often appears where airflow is restricted against a cold wall, but not every patch is condensation. Check the pattern first, then improve airflow, ventilation and humidity control while ruling out leaks or rain penetration.
Read guide →Condensation forming on the internal surface of external walls occurs when the wall temperature drops below the dew point of the indoor air. It indicates poor insulation, high humidity, or both.
Read guide →Mould behind beds forms when headboards are placed against cold external walls. The trapped air condenses, creating damp conditions for mould. Move the bed away from the wall and control humidity to prevent it.
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