Damp / mould / condensation / mould
What do black spots around my windows mean?
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.
Black spots around a window are often mould caused by repeated condensation, but colour alone cannot identify the cause or risk. Check where the spots are, when the area becomes wet and whether the frame or wall is damaged.
Start with the pattern.
Small dark dots or clusters appear on window seals, corners, reveals or the sill.
Possible causes, not a diagnosis.
- Repeated condensation is leaving the coldest edge damp.
- A seal, frame or wall junction is allowing water in.
- Dust and moisture have collected in a poorly ventilated area.
Check what is safe to observe.
- 01
Check whether the spots wipe from a hard surface or are embedded in porous material.
- 02
Look for water after rain, overnight condensation and damaged sealant.
- 03
Photograph the pattern and check if it is spreading beyond the window area.
Take the smallest useful step.
- Ventilate and dry the area, then use a labelled product for a small hard-surface spot.
- Keep the sill clear so water does not pool.
- Arrange repair or investigation if the spots return.
- Do not use colour as proof of a particular damp type.
- Do not dry-brush or sand the spots if there is a larger affected area.
- Report recurring spots, damaged frames or damp plaster to a landlord or housing provider or window professional.
- Get professional remediation for larger areas or mould on porous materials.
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.