Blown fibre insulation, also known as loose-fill fibre insulation, is a type of insulation that is installed by blowing loose fibres into wall cavities. While blown fibre insulation can be an effective insulator, it can also present some problems in wall cavities, including:

1. Settling: Blown fibre insulation can settle over time, reducing its effectiveness as an insulator. This can result in uneven insulation coverage, with some areas having less insulation than others.
2.Moisture retention: Blown fibre insulation can absorb and retain moisture, which can lead to mold growth and rotting of the surrounding wood structures. This can compromise the structural integrity of the building and lead to costly repairs.
3. Fire hazard: Blown fibre insulation is flammable and can contribute to the spread of fire in the home.
4. Air leakage: Blown fibre insulation can settle and shift, creating gaps and voids in the insulation. This can allow air to leak through the wall cavities, reducing the insulation's effectiveness and increasing energy costs.
5.Pest infestation: Blown fibre insulation can attract pests such as rodents and insects, which can nest in the insulation and cause damage to the surrounding structures.

While blown fibre insulation can be an effective insulation material, it can also present problems in wall cavities, including settling, moisture retention, fire hazard, air leakage, and pest infestation along with being hard to isntall effetively. 

THis can be removed and repalced with EPS Bonded Beads.