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When are properties unsuitable for Cavity Wall Insulation?

We regularly come across properties that are unsuitable for cavity wall insulation. The following list comprises the most common reasons but it not intended to be exhaustive:

  1. Properties with elevations that are particularly exposed and susceptible to wind driven rain
  2. Timber framed properties
  3. Steel framed properties
  4. System built properties
  5. Properties with defective rainwater goods and/or unlined finlock guttering
  6. Properties where there are significant areas of perished mortar (require re-pointing) or masonry
  7. Properties that are experiencing issues with penetrative damp
  8. Properties without a DPC, or where the DPC is too low (typically less than 125mm from the ground) and a French drain has not been installed
  9. Some properties with raked mortar joints
  10. Properties with a cavity wall under 40mm or over 150mm
  11. Properties that have significant rubble or mortar ingress in the cavity

We are regularly called to survey properties that exhibit these characteristics but have been filled with cavity wall insulation. The outcome is often that it has become damp and is now causing a range of further problems. In this situation, it is almost certain that the cavity wall insulation extraction will be needed.

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2 thoughts on “When are properties unsuitable for Cavity Wall Insulation?

  1. I’ve got cavity walls with an inch (25mm) of expanded polystyrene “attached” to the inside wall.

    Are you able to fill the empty part please?
    Or get the polystyrene out and refill please?

    Kind Regards, Mike

    • Hi Mike,

      Thanks for your enquiry. Firstly, it is not possible to (easily) extract the expanded polystyrene. This will be a Celotex or Kingspan ‘sheet’ that will have been fitted during construction. Removing it would require major sections of the outer skin of brick being removed. Cavities of this type are known as ‘partial fill’.

      It is possible to refill the remaining ’empty’ cavity as long it is suitable to do (a minimum of 50mm, clean, dry and with the existing board securely pinned to the inner wall). This would all be subject to detailed survey. You can arrange this by calling our office on 01926 831851.

      Please let me know if we can be of any further assistance.

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