Why is my wall damp?

What causes dampness & what can I do to stop damp?

Determine what source(s) of water could be in contact.

  • Rainwater,
  • Mains or wastewater leak,
  • Groundwater,
  • Vapour – condensation the most common cause of damp.

Top 10 tips for finding and stopping damp

  1. Log humidity over a week.
  2. Check that ventilation is sufficient.
  3. Look for signs of mould.
  4. Use a damp meter to
    • Find the centre(s) or line of greatest damp.
    • Find extent of damp.
    • Profile the damp on both sides of a wall.
  5. Measure and profile heat loss with a laser thermometer.
  6. Note look of surface damp, surface salts and discolouration. Consider testing salts for nitrates.
  7. Consider effect of property changes from; weathering, damage, usage, extensions and modernisation.
  8. Look outside for signs of damage to rainwater goods.
  9. Look for signs of high groundwater and refer to online data sources.
  10. If there is a sub-floor;
    • Measure the sub-floor humidity.
    • Check adequacy of sub-floor vents.

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