When comparing rockwool to glass wool or foam insulation, a few differences become clear. Glass wool is generally less expensive upfront but doesn’t match rockwool’s density or resistance to fire. Foam insulation offers excellent airtightness but typically falls short on acoustic and combustibility performance.
As a high-density material, rockwool holds its shape over time, reducing settling and maintaining consistent coverage through the life of the building. In wall assemblies, this structural stability translates into reliable, long-term performance. That’s one of the reasons so many builders and insulation suppliers consistently recommend it. See our glasswool insulation guide for a closer look at how standard glass wool batts compare on their own.
Fire Resistance Rockwool is the clear winner. Made from volcanic rock, it withstands temperatures above 1000 degrees Celsius without burning or releasing toxic smoke. Earthwool is also non-combustible but does not reach the same benchmarks, while glasswool falls further behind. For any project where fire ratings are legally required, rockwool is the only real choice.
Acoustic Performance Rockwool’s high density gives it a natural advantage in blocking and absorbing sound, consistently outperforming both earthwool and glasswool. It is the preferred choice for party walls, between-floor applications, and any space where noise control is a priority.
Thermal Performance All three materials deliver solid thermal performance, but rockwool edges ahead with an R-value of 3 to 4 per inch compared to earthwool and glasswool at 2.2 to 2.7 per inch, meaning better thermal resistance for the same wall thickness.
Moisture Resistance Rockwool is naturally water repellent and holds its shape even in damp conditions. Earthwool and glasswool can absorb moisture over time, reducing effectiveness and potentially encouraging mould. For bathrooms, basements, or any moisture-prone area, rockwool is the safer choice long term.
Cost Rockwool is generally two to three times more expensive than earthwool in Australia. However, its superior durability and performance across fire, acoustic, and moisture categories make it a worthwhile investment for the right application.
Which One Should You Choose? For fire-rated walls, acoustic separation, and high-moisture environments, rockwool is the strongest performer available. For standard residential projects where budget is the priority, earthwool remains a reliable alternative. No Gap Insulation stocks a full range of rockwool products across Victoria and New South Wales — contact the team today for a free quote.
