Why your cavity walls must be clear

Cavity walls are designed to prevent water penetrating the internal walls of your home. The air space between the inner and outer walls allows any water that does get in to drain down to the footings.

However, for this to work the cavity must be completely clear.
NB: The only exception to this is when an appropriate insulation material is expertly installed.


How a cavity may be blocked

The cavity may become blocked because:

  • It was not cleared correctly when the house was constructed
  • Debris got in during building work, such as replacing windows or fitting a conservatory
  • Debris got in during improvements and repairs, such as fitting a balanced flue boiler system or a vent

This debris can form a bridge that carries moisture across to the interior of the house, which in time will cause penetrating damp and mould.

Therefore, even if you’re not planning on having cavity wall insulation installed, it’s vital that the cavities of your home are clear.


Our cavity wall cleaning process

Our BBA approved process takes just a day or two to clear the cavities of an average semi-detached home. It’s suitable for almost all properties with cavity walls and can be used to clean all the cavities or just those where debris is known to be.

  1. We undertake a thorough survey of your home, including the condition of your external and internal walls and any existing areas of damp. We can then let you know how much it will cost to clean your cavities.
  2. We prepare the site and erect scaffolding if necessary.
  3. We create 5 – 10 openings at damp proof level in the external wall by removing bricks at predetermined distances.
  4. We fix specially designed extraction covers to the openings and attach an extractor.
  5. We drill a series of holes in the mortar line or render and use air pressure to force the debris down to the extractor.
  6. We inspect the cavity at regular intervals throughout the extraction using a 360o video boroscope that gives us a 2m view in every direction.
  7. When the extraction is complete and we’ve confirmed all the cavities are completely clear we reinstate the walls and return your home to its original state.
  8. We clear and clean the site.
  9. We carry out a final inspection of your property.
  10. Our technician fills out and signs a completion certificate, which we ask you to sign as well.

Cavity wall insulation removal

Cavity wall insulation can also cause penetrating damp in your home if it has debris in it (as well as for a number of other reasons).

We use the same process to remove cavity wall insulation as we do to remove debris.