Glasswool Insulation

What Is Glasswool Insulation?

Glasswool insulation, sometimes called glass wool or fibreglass insulation, is a fibrous bulk insulation product made from countless fine glass fibres bound together into a blanket, roll, or rigid slab. As the fibres are formed, they trap millions of tiny pockets of air throughout the material. It's this trapped air, not the glass itself, that gives glasswool its insulating power — the fibres are a poor conductor of heat, so the trapped air pockets slow the transfer of heat through a ceiling, wall, or floor far more effectively than an empty cavity ever could.

How Is Glasswool Insulation Made?

Most glasswool insulation begins with recycled glass rather than raw silica sand alone. Manufacturers typically combine two recycled glass streams: plate glass, sourced from old windows and windscreens, and container glass, sourced from bottles and jars. This mixture is melted in a furnace at temperatures around 1,400°C, then spun into fine fibres and bonded together with a binder that holds the finished product in its rolled or slab form.

Many modern glasswool products, including Knauf Earthwool, use a bio-based binder rather than older formaldehyde-based formulas, meaning the finished insulation contains no added formaldehyde, colours, or dyes. Combined with the fact that most glasswool is manufactured from up to 80% recycled glass content, it's a genuinely more sustainable choice than many people assume.

Is Glasswool Insulation Safe to Handle?

It's a fair question, and worth answering properly rather than glossing over. Handling glasswool can cause mild, temporary skin irritation, but this is purely mechanical — a result of the fibres' physical strength and shape, not a chemical reaction. There's no evidence of any long-term skin irritation once loose fibres are washed off, and glasswool does not cause dermatitis or any other lasting skin condition.

Glasswool sold in Australia today must also be manufactured from Bio Soluble Fibres, meaning the fibres break down in the body faster than ordinary dust particles. This standard has been extensively researched and is not associated with any adverse long-term health effects, giving installers and homeowners genuine peace of mind alongside standard precautions like gloves, long sleeves, and a mask.

Key Benefits of Glasswool Insulation

• Outstanding thermal and acoustic performance — maintains stable indoor temperatures while also reducing noise transfer between rooms
• Non-combustible — made primarily from glass, giving it a genuine fire safety advantage over combustible materials
• Durable and high tensile strength — soft to the touch yet resilient, holding its shape and performance over decades of use
• Reduces energy bills — slows heat transfer through ceilings, walls, and floors, easing the load on heating and cooling systems
• Manufactured from up to 80% recycled glass — a genuinely lower-impact choice than many alternative insulation materials
• Easy to handle and install — a softer feel than older-style products makes for a more comfortable, achievable DIY project

Glasswool Insulation Brands We Stock

We carry a wide range of glasswool insulation products from Australia's leading manufacturers, including Knauf Earthwool, Fletcher Pink Batts, and Bradford Insulation. Between these brands, you'll find batts, blankets, and slabs suited to ceilings, internal and external walls, underfloor spaces, and dedicated acoustic and thermal performance applications across your entire home.

Tips for Installing Glasswool Insulation

Correct installation makes a real difference to how well glasswool performs:

• Fit each insulation batt snugly into the cavity, but avoid compressing it — compression reduces the trapped air pockets and compromises the batt's effective R-value.
• Run wiring either in front of or behind the insulation batts rather than through them where possible.
• Cut the insulation neatly to make space for power outlets and LED downlights, rather than forcing the batt around them.
• Avoid leaving gaps between batts, since gaps allow air flow, draughts, and condensation to bypass the insulation layer entirely, reducing its overall effectiveness.

Glasswool vs Rockwool

Glasswool and rockwool are often compared, and for good reason — both are non-combustible, both offer strong thermal and acoustic performance, and neither causes dermatitis or lasting skin conditions. Glasswool tends to be the more affordable, widely available option for standard residential applications, while rockwool can offer additional moisture resistance for more specific or demanding uses.

Shop Our Glasswool Insulation Range

Browse our full range of glasswool insulation batts, blankets, and slabs from Knauf Earthwool, Fletcher Pink Batts, and Bradford Insulation below, or get in touch with our team for help selecting the right R-value and product for your ceiling, wall, underfloor, or acoustic project.