Damp / mould / condensation / condensation
Why is there condensation on my windows?
Start with the observable symptom. This page explains possible causes; it is not a diagnosis. It covers both “mould” and “mold” wording for the same intent.
Condensation on the inside of a window usually means warm, moist indoor air is meeting a colder surface. It can be a ventilation or heating issue, but persistent water should also prompt checks for leaks, failed seals or a wider damp problem.
Start with the pattern.
Water droplets or a misty film appear on the room-facing glass or frame.
Possible causes, not a diagnosis.
- Moisture from cooking, bathing or drying clothes is not escaping quickly enough.
- The glass, frame or surrounding wall is colder than the room air.
- If moisture is between double-glazed panes, the sealed unit may have failed rather than the room simply being humid.
Check what is safe to observe.
- 01
Note whether the water is on the room side, outside, or between the panes.
- 02
Check whether the room has a working extractor, trickle vent or opening window.
- 03
Look for mould, peeling paint or damp around the frame and the wall below it.
Take the smallest useful step.
- Use kitchen and bathroom extraction during moisture-producing activities and for a short period afterwards.
- Wipe excess water from sills and frames, then dry the area.
- Keep furniture and curtains from blocking airflow around the window.
- Do not assume every wet window is rising damp.
- Do not seal over mould or paint damage before the moisture source is understood.
- Ask a landlord or housing provider to inspect recurring condensation, visible mould or damaged window seals in a rented home.
- Use a qualified professional if water is between panes, enters after rain, or has damaged the wall.
Professional requirements and rental responsibilities vary by location. Use the qualified local professional or housing authority that applies where you live.
UK example: GOV.UK repairs guidanceWhy this page says that.
This page separates an observable symptom from possible causes and keeps the recommended action within a safe household boundary.