Why mould appears
Mould usually develops where humidity, poor ventilation and favourable temperature conditions come together.
Common causes
- condensation and excess indoor humidity;
- poor air renewal;
- cold corners, ceilings or wardrobes;
- local water ingress in some cases;
- rooms with little airflow.
Important: mould is often the visible symptom, not the real origin of the problem.
Why cleaning it is not enough
You can remove the stain, but if the indoor conditions remain the same, mould often comes back.
What makes more sense
If the origin is condensation, the approach should focus on ventilation and indoor air renewal. If there is an external water entry point, that cause must be resolved first.
Conclusion
Mould should be treated as a warning sign. The right approach is to understand why it appears and act on the cause, not just on the visible stain.