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What Causes Damp?

We are frequently asked "what causes damp?"

It's a huge subject, but I guess you could re-phrase it to say "What causes damp walls?" Elsewhere on the site, other pages drill down into the reality of the subject.  In short, damp walls are only damp because they are in some way prevented from drying out. They may be damp because they have cement render outside.  They may be pointed with cement.  They may have damp proofing tanking compounds and gypsum plaster on the inside.  

There will always be a genuine reason for the wall to be damp - quite rare, in our experience - but these are a few of the things it can be:

  1. Penetrating damp from leaky gutters and downpipes
  2. Penetrating Damp from high external ground levels
  3. Penetrating damp from splash - a leaky overflow pipe
  4. Base of wall soaked by a leaking drain
  5. Salts soaking a wall from a chimney
  6. Water trapped behind a cement plinth at base of wall
  7. Excessive vegetation planted by a wall
  8. Rarely - horizontal driving rain
  9. Leaks around windows
  10. Leaky roof
  11. Interstitial Condensation - this is actually the biggest cause of moisture in building fabric - and is actually what 'rising damp' is all about.  Rising Damp is Interstitial Condensation

 

Other causes of damp tend to be environmental - excessive humidity in the house, being trapped into the wall because of cement or tanking compounds.   

A very big current problem we deal with is in cavity walls - where cavity insulation is sopping wet from condensation.  If you have a confirmed case of wet cavity insulation - Contact Civalli for help.

Damp in floors is rarer - but if you have a traditional tiled floor over limecrete or old clay tiles or stone flags for example, putting impermeable lino or carpet on it will cause major problems of tapped moisture - removing the lino lets it dry out.

Lino trapping moisture in floor

Lino trapping moisture into terracotta tiles, on a limecrete base.  The house was sopping wet.  Removing the lino allowed the floor, and thus the house, to dry out.

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