What is glass wool?
Glass wool is made from molten glass, largely from recycled glass, which is spun into fine fibres. There is a lot of trapped air between these fibres, and it is precisely this air that provides the insulating effect.
For cavity walls, glass wool is used in the form of loose flakes, which are blown into the cavity.
How glass wool is installed in the cavity wall
First, we check if the cavity is suitable, including an inspection through a small hole in the mortar joint. Then, we drill small holes at regular intervals in the mortar joints of the outer wall.
Through these holes, we blow the glass wool flakes into the cavity until the entire space is evenly filled. Finally, the holes are sealed with a mortar colour that matches the existing brickwork.
Benefits of glass wool in the cavity wall
- Fills the cavity evenly, even around obstacles
- Water-repellent: does not absorb moisture from the outer wall
- Vapour-permeable, allowing the wall to breathe
- Non-combustible material
- Does not shrink or settle when correctly filled
- Quickly installed, usually within one day
Is my cavity wall suitable for glass wool?
Most homes built between approximately 1920 and 1975 have an uninsulated cavity wall. Whether glass wool is suitable depends on the width and condition of the cavity and the mortar joints. We prefer to repair poor mortar work first.
Our advisor will assess this free of charge at your home and honestly tell you if cavity wall insulation is a viable option for your property.
Grant for cavity wall insulation
Cavity wall insulation may, under certain conditions, be eligible for the national ISDE grant and for municipal schemes. We check the possibilities and arrange the application.
Frequently asked questions
How long does glass wool in the cavity wall last?
Properly installed glass wool retains its insulating properties for decades.
Can glass wool cause moisture?
Glass wool for cavity walls is water-repellent and vapour-permeable. With a healthy facade and good mortar work, this does not cause moisture problems.
What is the difference from UF foam?
UF foam was widely used in the past but can shrink and crumble. Read more in our article about UF foam in cavity walls.