Before you have your cavity insulated you may need a ‘cavity cleanse’ to rid the cavity of obstructions such as discarded bricks, mortar droppings or dust that has entered the cavity and built up over many years.
These porous obstructions will ‘bridge’ the cavity allowing rain water to make its way from the outer bricks, across the obstruction and on to the inner blocks. This will lead to internal damp issues and must be rectified as soon as possible, even if you’re not having cavity wall insulation installed. In some cases these obstructions will also breach the damp course leading to rising damp problems.
Therefore, when cavity cleaning is identified as necessary during the suitability survey it is essential to complete this work before the insulation is installed.
This is not a simple process and should only be completed by professionals with the necessary skills, equipment and machinery to complete this work.
Typically a semi-detached house cavity cleanse will cost between £400 and £600.