Why is my wall 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.