When problems occur with cavity wall insulation
When retrofit cavity wall insulation is installed into a property that is located or built in a way that means it should not have the cavities filled, or if the work is undertaken incorrectly, the first and most obvious sign of a problem is almost always internal dampness.
Most homeowners will be blissfully unaware if cavity wall insulation has not been installed correctly. You will not know if it is over-packed, under filled, where it has slumped, where areas have been missed, vents have been blocked or obstructions missed. Its simply very difficult to see obvious signs of any defect. Those that are aware of a problem with the cavity wall insulation within the walls will almost certainly have been put on notice with the appearance of dampness within their home.
On occasion, the use of cavity wall fills should have been a part of a suite of measures to improve thermal performance. However, all too often it’s the only measure that’s been utilised. Where cavities are discontinuous or are crossed by solid elements such as floor slabs, or parapets, “cold bridges” can be left. Before the insulation was installed the temperature difference between these bridges and the wall may have been relatively small. After the cavities within the walls are filled with insulation these un-insulated elements may be significantly colder than the surrounding walls. This coupled with the effects of a draughty house, can create the right conditions for condensation and mould, often where it’s not been seen before.
We have also seen a growing number of properties where no defects exist with the building or the new insulation, but owners are reporting new problems with damp. In these instances, it has been found that the insulation has successfully stopped both warm air and moisture escaping. Without reintroducing air exchange through controlled ventilation the wet air has nowhere to go. Subsequently the humidity levels rise and mould growth is almost inevitable.