00VILLA GUIDE
Damp and mould in a villa: telling the causes apart
A damp patch or mould spot is a symptom with many possible causes: a pipe leak, failed waterproofing on a roof or terrace, rain getting past a window, irrigation soaking a wall, ground moisture, or simply condensation on a cold surface. The repair depends entirely on which one it is, so the first job is always to work out the cause.
01PART
When does it appear?
Timing is the most useful clue. Damp after rain points to the roof, terrace or windows; damp when AC runs hard to condensation; damp after showers to the bathroom; damp after watering to irrigation; constant damp to a supply leak or ground moisture.
- After rain: roof, terrace, windows.
- With AC: condensation.
- After watering: irrigation.
02PART
Where is it?
Ceilings under bathrooms and terraces, walls behind planters and fountains, low walls with salt bloom, and wardrobes on outside walls each suggest particular causes.
- Ceilings: above-floor water.
- Low walls: ground or irrigation.
- Behind furniture: condensation.
03PART
Measure, then repair
Moisture readings in the substrate, surface temperature and humidity separate a leak from condensation. Only then is the right repair clear.
- Take moisture readings.
- Check humidity.
- Repair the cause, then finishes.
04QUESTIONS
- Is mould always from a leak?
- No; condensation causes much villa mould.
- Why does damp return after repainting?
- The cause was not fixed.
- Can irrigation cause damp inside?
- Yes, when it soaks walls or foundations.
- What should I record?
- When the damp appears and what happened just before.
- Can there be more than one cause?
- Yes. A wall can be wetted by irrigation outside and condensation inside at the same time, so each possible source is checked before repairs start.