Cavity Wall Insulation Problems

Cavity wall insulation causing damp is very rare, but it's worth checking whether your home's at risk. You can use the checklist below to assess your home's damp risk. Ask our installer about these factors, too.

Damp could occur in properties as a result of cavity wall insulation if there is a combination of these factors:

  • Your home is exposed to severe levels of wind-driven rain (zones three or four in our Map Here )
  • Cold spots in the cavity as the wrong drill pattern or blowing pressure has left void spots which may lead to condensation.
  • The wrong insulation material has been used for your property.
  • Two types of insulation have been installed. This should not have happened!
  • Your home is located in an unsheltered position, eg not protected by trees or other buildings
  • The external walls are poorly built or maintained with, for example, cracks in the brickwork or rendering.

Published guidance by the Building Research Establishmentsays that in these cases there is 'an increased risk of rain penetration if a cavity is fully filled with insulation'. Rain could penetrate the outer wall, bridge the cavity via the insulation material and transfer moisture to internal walls, causing damp. 

UK Rain & Wind Map