Glass Fibre and Glass Wool - What's the Difference

Glass wool insulation is made from recycled glass bottles, sand, and other materials. Glass wool is just another name for glass fibre insulation. It is also sometimes referred to as glass fibre insulation or glass fibre segments. They are melted at very high temperatures and then spun into fibres. The result is that millions of tiny air pockets are created inside the insulation, which is what gives glass wool insulation its outstanding insulating properties.

Glass fibre wool - like sheep's wool and down

You may be surprised to find that glass wool insulation works in a very similar way to natural wool and down feathers. Various adhesives can be used to hold the insulation together. For decades, the glass wool part has been associated with eye, nose, skin, and throat irritation, but fortunately, technological developments have led to huge improvements in product design and softer, more comfortable insulation is now available on the market.

Foil-Clad Glass Wool     

Glass wool insulation - always dry!

Wet insulation is a dilemma at the best of times and glass wool insulation is no exception. It is easy to see why wet insulation does not work and can cause endless problems for homeowners if installed in wet conditions. Firstly, glass wool relies on the microscopic air gaps within - which are technically the true insulators. Now, if these get soaked with water, then your insulation is gone! In addition, wet glass wool insulation is prone to mould and introduce moisture into any installed area of the building, with potentially damaging results. For this reason, glass insulation should always be stored in an elevated and dry area, and if any part of the glass wool section becomes wet, it should be cut off, discarded and never used.

Why is glass wool insulation still so popular?

Glass wool insulation is still very popular, and for good reason. Much of the insulation comes from sand, one of the world's most abundant natural resources. Other additional benefits of glass fibre insulation segments are that they are resistant to pests and are non-combustible (won't catch fire) - an obvious benefit considering that they are always installed within the actual building frame. When installed correctly in the roof, ceiling or under the floor of a house, glass wool insulation can last as long as the house itself.

How is glass fibre made?

As the name implies, recycled glass is the key ingredient in the manufacture of glass wool insulation. Together with other ingredients (such as soda ash, limestone and most sand), this mixture is heated to its melting point and then spun into long, ultra-fine glass fibre strands. A binder is added to the mixture and, after baking in a large oven, the insulation is cut into thin sheets and cooled before being packaged.