Rock wool (stone wool / mineral wool) is a high-performance insulation made by melting basalt rock & slag at ~1500 °C and spinning it into dense fibres. Its standout properties are exceptional fire resistance (withstands 1000 °C, non-combustible), excellent acoustic absorption, and high-temperature thermal insulation. It is the preferred insulation for fire-rated assemblies, industrial high-temperature applications, acoustic walls, and fire barriers.
Indian rock wool follows IS 8183 (Bonded Mineral Wool). Major brands: Rockwool India, Lloyd Insulations, UP Twiga, Saint-Gobain ISOVER, Beardsell, Minwool.
Rock wool is manufactured from natural basalt / dolomite rock and steel slag, melted and spun into fibres bonded with resin. The dense, fibrous structure traps air and resists heat, sound and fire. It is water-repellent (treated), dimensionally stable, and retains performance at high temperatures where glass wool fails.
| Property | Value |
|---|---|
| Thermal Conductivity (k) | 0.034–0.044 W/m.K |
| Density | 32, 48, 64, 96, 100, 120, 150 kg/m³ |
| Fire Rating | Non-combustible (A1, up to 1000 °C) |
| Melting Point | > 1000 °C |
| Sound Absorption (NRC) | 0.90–1.0 |
| Max Service Temp | up to 750–850 °C |
| Water Absorption | Very low (water-repellent) |
| Vapour Permeable | Yes (breathable) |
| Form | Use |
|---|---|
| Slabs / Boards | Walls, fire barriers, facades |
| Rolls / Blankets | Roofs, large areas |
| Lamella / Strips | Curved surfaces, pipes |
| Pipe Sections | High-temp pipe insulation |
| Loose Wool | Fire-stopping, gap filling |
| Foil / Tissue Faced | Vapour barrier, exposed |
| Wire Mesh Mattress | Industrial high-temp |
| Parameter | Rock Wool | Glass Wool |
|---|---|---|
| Raw Material | Basalt rock + slag | Glass / silica sand |
| Max Temperature | 750–1000 °C | 250–500 °C |
| Fire Resistance | Superior (fire barrier) | Good (non-combustible) |
| Density | Higher (denser) | Lower (lighter) |
| Acoustic | Excellent | Excellent |
| Water Repellent | Yes | No (bare) |
| Cost | Higher | Lower |
| Best For | Fire + high-temp + acoustic | Thermal + acoustic, HVAC |
See Glass Wool for the lighter, lower-temperature alternative.
| Brand | Products |
|---|---|
| Rockwool India | Rockwool slabs, fire batts, ProRox |
| Lloyd Insulations | Resin-bonded rock wool |
| UP Twiga | Mineral wool products |
| Saint-Gobain ISOVER | Stone wool |
| Beardsell / Minwool | Mineral wool |
| Standard | Description |
|---|---|
| IS 8183 | Bonded Mineral Wool — Specification |
| IS 3144 | Mineral Wool Test Methods |
| ASTM C518 / C423 | Thermal / Acoustic Tests |
| ASTM E136 / EN 13501 | Non-Combustibility / Fire Classification |
| IS 3346 | Thermal Conductivity |
| BS 476 / EN 1366 | Fire Resistance Tests |
| Type | Cost |
|---|---|
| Rock Wool Slab 50 mm 48 kg/m³ (per sqm) | Rs 90 – 180 |
| Rock Wool Slab 50 mm 96 kg/m³ (per sqm) | Rs 150 – 300 |
| Rock Wool Roll (per sqm) | Rs 60 – 130 |
| Foil-Faced Rock Wool (per sqm) | Rs 120 – 250 |
| Fire Batt (per sqm) | Rs 150 – 350 |
| Installed (per sqft) | Rs 25 – 60 |
Rock wool is the premium choice when fire resistance and high-temperature performance matter — fire-rated walls, fire-stopping, industrial insulation, and acoustic treatments. It outperforms glass wool on temperature (up to 1000 °C) and water repellency, at a higher cost & weight. Use PPE during installation, choose density per application, and verify fire ratings for fire barriers.
For lighter, lower-cost thermal / acoustic needs, use glass wool; for rigid thermal boards, EPS / XPS; for radiant heat, reflective foil; for gap-filling, PU foam. Pairs with gypsum board for fire-rated drywall.