This is due to the capillary action of the bead allowing gravity to draw any moisture present down the inner surface of the outer leaf to drain away at foundation level.
Cavity wall insulation beads leaking.
Eps expanded polystyrene beads and polyurethane foam are the most commonly used these days and with good reason.
If you re installing cavity wall insulation it s worth opting for a modern insulating material with proven performance.
When beads are injected into the cavity wall they are injected with a upvc glue which binds all the beads together.
The process seems simple drill into the outer wall inject a fibre or bead insulation into the cavity make good the holes sit back and enjoy reduced energy bills.
Plumbing pipes and leaks copper water pipes in the wall are usually secure but occasionally one may develop pinhole leaks and spray enough water to cause insulation problems.
The problem is that this fills the cavity with a material that can allow water to cross the cavity causing dampness and if the material is not evenly distributed cold spots where insulation is missing can attract condensation.
The bonding agent creates a stable continuous layer within the cavity preventing any movement or sagging of the insulation over time and also any loss of bead if the walls are drilled at a later date.
Why are the beads bonded together.