Glass wool (glasswool / fibreglass insulation) is a lightweight insulation material made from molten glass spun into fine fibres, trapping millions of tiny air pockets that resist heat & sound transmission. It is one of the most widely used insulation materials for thermal insulation (roofs, walls, HVAC ducts) and acoustic insulation (auditoria, studios, partitions). It is fire-safe (non-combustible), light, and easy to install in rolls, slabs or batts.
Indian glass wool follows IS 8183 (Bonded Mineral Wool). Major brands: UP Twiga Fiberglass, Owens Corning, Lloyd Insulations, Saint-Gobain ISOVER, Rockwool India, Beardsell.
Glass wool is manufactured by melting glass (silica sand + recycled glass) at ~1400 °C, then spinning it into fine fibres bonded with resin. The fibrous mat traps air, making it an excellent insulator. It is supplied as rolls, slabs (boards), batts, pipe sections, with or without facings (aluminium foil, fibreglass tissue, wire mesh).
| Property | Value |
|---|---|
| Thermal Conductivity (k) | 0.030–0.040 W/m.K |
| Density | 16, 24, 32, 48, 64, 100 kg/m³ |
| R-Value (50 mm, 32 kg/m³) | ~1.4 m²K/W |
| Sound Absorption (NRC) | 0.85–0.95 (higher density) |
| Fire Rating | Non-combustible (Class A / A1) |
| Max Service Temp | 250–500 °C (binder dependent) |
| Water Absorption | Low (with facing); hygroscopic if bare |
| Thickness | 25, 50, 75, 100 mm |
| Form | Description | Use |
|---|---|---|
| Rolls / Blankets | Flexible rolls | Roofs, large areas, ducts |
| Slabs / Boards | Rigid panels | Walls, acoustic panels |
| Batts | Pre-cut pieces | Stud walls, ceilings |
| Pipe Sections | Cylindrical | Pipe / duct insulation |
| Foil-Faced | Aluminium foil facing | Vapour barrier, reflective |
| Tissue / Mesh-Faced | Glass tissue / wire mesh | Acoustic, exposed |
| Resin-Bonded | Rigid, higher temp | Industrial, HVAC |
| Parameter | Glass Wool | Rock Wool | EPS |
|---|---|---|---|
| Material | Spun glass fibre | Spun basalt rock | Expanded polystyrene |
| Thermal k (W/m.K) | 0.030–0.040 | 0.034–0.044 | 0.033–0.040 |
| Acoustic | Excellent | Excellent | Poor |
| Fire | Non-combustible | Non-combustible (1000 °C) | Combustible |
| Max Temp | 250–500 °C | up to 750–1000 °C | ~80 °C |
| Water Resistance | Low (bare) | Water-repellent | High |
| Cost | Low-Medium | Medium | Low |
| Best For | Thermal + acoustic, HVAC | Fire + acoustic, high-temp | Thermal, lightweight |
See Rock Wool and EPS / Thermocol.
| Brand | Products |
|---|---|
| UP Twiga Fiberglass | Twiga Glass Wool rolls, slabs, ducts |
| Owens Corning | OC glass wool, acoustic |
| Lloyd Insulations | Resin-bonded glass wool |
| Saint-Gobain ISOVER | ISOVER glass wool |
| Beardsell | Glass wool products |
| Superlon / U.P. Twiga | HVAC insulation |
| Standard | Description |
|---|---|
| IS 8183 | Bonded Mineral Wool — Specification |
| IS 3346 | Thermal Conductivity Test Method |
| IS 3144 | Mineral Wool Test Methods |
| ASTM C518 / C423 | Thermal / Acoustic Tests |
| ASTM E136 | Non-Combustibility |
| ECBC 2017 | Building Insulation Requirements |
| Type | Cost |
|---|---|
| Glass Wool Roll 50 mm 24 kg/m³ (per sqm) | Rs 35 – 70 |
| Glass Wool Slab 50 mm 48 kg/m³ (per sqm) | Rs 70 – 140 |
| Foil-Faced Glass Wool (per sqm) | Rs 60 – 130 |
| Acoustic Glass Wool 48–64 kg/m³ (per sqm) | Rs 90 – 180 |
| Duct Wrap (per sqm) | Rs 45 – 100 |
| Installed (per sqft, roof / wall) | Rs 15 – 45 |
Glass wool is the versatile, economical choice for both thermal and acoustic insulation — widely used in roofs, HVAC ducts, walls, false ceilings and acoustic treatments. Choose lower density for thermal, higher density for acoustic, and foil-faced versions where a vapour barrier is needed. Always use PPE during installation, keep it dry, and avoid compression.
For higher fire / temperature resistance, see rock wool; for rigid lightweight thermal boards, see EPS and XPS; for radiant heat, reflective foil; for spray / gap-filling, PU foam. Often paired with gypsum board false ceilings for acoustic comfort.