mineral / Glass / Glass Products
Glass Wool Insulation
Mineral glass fiber insulation in batt and blanket form for thermal and acoustic insulation in walls and roofs
Atlas code
MIN-GLA-PRO-011
At-a-glance signals
Mineral glass fiber insulation in batt and blanket form for thermal and acoustic insulation in walls and roofs
Overview
Executive summary
Glass wool (also called fibreglass insulation or glasswool) is a mineral fibre thermal and acoustic insulation material manufactured by spinning or blowing molten glass (containing 40-80% recycled glass cullet) into fine fibres bonded with a thermosetting resin binder. Available in batts, blankets, and rigid/semi-rigid boards across a wide range of R-values (R1.5 to R7.0+), glass wool is the most widely used insulation material in Australian residential and commercial construction. It is non-combustible when tested to AS 1530.1, has excellent thermal performance (thermal conductivity 0.030-0.044 W/mK), and provides significant acoustic absorption (NRC 0.90-0.95). Major Australian manufacturers include Bradford (CSR), Fletcher Insulation (Pink Batts), and Knauf Insulation (Earthwool), all producing locally with high recycled content. Glass wool products are CodeMark certified and comply with AS/NZS 4859.1:2018 for thermal insulation materials and NCC energy efficiency provisions (Section J for commercial, Part H6 for residential).
Best when…
- Excellent thermal performance with very low thermal conductivity (0.030-0.044 W/mK)
- Non-combustible per AS 1530.1 - does not contribute to fire load
- Most cost-effective insulation option in Australia ($6-12/m2)
- High recycled content (40-80% recycled glass)
- Excellent acoustic absorption (NRC 0.90-0.95)
- Wide range of R-values and sizes for all Australian climate zones
- Locally manufactured in Australia by multiple suppliers
- Lightweight and easy to handle and install in standard framing
- CodeMark certified for NCC compliance
Top advantages
- 01 Excellent thermal performance with very low thermal conductivity (0.030-0.044 W/mK)
- 02 Non-combustible per AS 1530.1 - does not contribute to fire load
- 03 Most cost-effective insulation option in Australia ($6-12/m2)
- 04 High recycled content (40-80% recycled glass)
- 05 Excellent acoustic absorption (NRC 0.90-0.95)
Top limitations
- 01 Skin, eye, and respiratory irritation during handling and installation (fibres)
- 02 Performance degrades significantly if compressed or wet
- 03 Does not provide air sealing - requires separate vapour barrier in some climates
- 04 Settles over time in vertical applications if not adequately supported
- 05 Lower acoustic performance than mineral (rock) wool at same density
Technical
Physical ·9
- Density
- 11-96 kg/m3 Varies with product type. Standard batts 11-14 kg/m3. High-density acoustic 24-48 kg/m3. Rigid boards 48-96 kg/m3. Source: Knauf Insulation TDS, Bradford product data, AS/NZS 4859.1
- Specific gravity
- 0.011-0.096 Very low due to air content. Bulk density much lower than glass material density
- Porosity
- >95 % Highly porous open-fibre structure. Air comprises >95% of volume in standard batts. This porosity provides thermal insulation
- Water absorption
- <1 (fibre), high (bulk wicking) % Glass fibres are non-absorbent but the open structure allows water to wick through. Performance severely degraded when wet. DriTherm technology provides moisture resistance in some products
- Hardness
- N/A Mohs Not applicable - soft fibrous material that compresses easily
- UV resistance
- Poor (binder degrades) UV degrades the binder over time causing fibre release. Must be covered and not exposed to direct sunlight in service
- Chemical resistance
- Good Glass fibres resistant to most chemicals. Binder may degrade in some chemical environments. Resistant to rot, mildew, and biological attack
- pH tolerance
- 3-10 pH Glass fibres are chemically inert. Binder may degrade in strongly alkaline conditions
- Surface roughness
- N/A um Fibrous surface. Not applicable in conventional sense
Mechanical ·7
- Tensile strength
- <0.01 MPa Very low - fibrous material tears easily. Sufficient for self-support in friction-fit cavity applications
- Compressive strength
- N/A (batts), 0.020-0.080 (rigid boards) MPa Standard batts compress easily. Rigid boards: compressive strength at 10% deformation typically 20-80 kPa. Source: Fletcher Thermal Slab data
- Flexural strength
- N/A MPa Not applicable for batts. Rigid/semi-rigid boards have limited flexural resistance
- Shear strength
- N/A MPa Not applicable - non-structural material with negligible shear resistance
- Poisson's ratio
- N/A Not applicable - compressible fibrous material
- Impact resistance
- N/A J Not applicable - soft compressible material
- Creep resistance
- Poor (batts), Moderate (rigid boards) Standard batts will compress under sustained load. Rigid boards have good creep resistance at rated loads
Sustainability & Health
Embodied carbon & energy ·7
- Embodied carbon
- 1.2-1.8 kg CO2-eq/kg Low embodied carbon compared to alternative insulation types. Glass wool: 0.6-1.2 kg CO2-eq per functional unit (1 m2 at R1.0 over 50 years). Per kg: approximately 1.2-1.8 kg CO2-eq/kg. Source: ScienceDirect critical review 2021, EPiC database (University of Melbourne), Greenspec
- Carbon footprint
- 1.5-3.0 kg CO2-eq/m2 Per m2 of R2.5 wall batt (~1.5 kg/m2). Very low per-area carbon footprint. Carbon payback through operational energy savings typically <2 years. Source: EPiC database, Ecohome
- Embodied energy
- 28-40 MJ/kg Energy-intensive glass melting offset by high recycled content and thin fibre production. 16-31 MJ per functional unit (1 m2 at R1.0). Per kg: ~28-40 MJ/kg. Source: ScienceDirect 2021 review, EPiC database
- Water footprint
- 5-15 L/kg Water used in manufacturing for cooling. Moderate water consumption in glass melting process
- Recycled content
- 40-80 % High recycled glass content. Bradford Gold: up to 65% recycled glass. Knauf Earthwool: minimum 40% recycled content. Fletcher: high recycled content. Source: Bradford product data, Knauf sustainability data
- Renewable content
- 0-5 % ECOSE Technology binder (Knauf) uses bio-based renewable materials instead of phenol-formaldehyde. Other manufacturers transitioning to bio-based binders
- Circular score
- 6.5 /10 Glass wool is technically infinitely recyclable as cullet. In practice, recovery from buildings is challenging (contamination, dust). High recycled input content. Diverts glass bottles from landfill. Source: ISOVER sustainability data
Compliance & Fire
Fire performance ·6
- Combustibility class
- Non-combustible (A1/A2) Non-combustible per AS 1530.1:1994. Unfaced glass wool up to 48 kg/m3 tested and classified as non-combustible by CSIRO. Euroclass A1/A2. Source: Bradford, Fletcher, Knauf
- Fire resistance level
- System dependent (contributes to 30-120 min FRL) minutes Glass wool contributes to wall and ceiling system FRL by protecting structural members. Fletcher Pink Thermal Slab achieves AS ISO 9705 Group 1 fire classification. System FRL depends on complete assembly
- Ignition temp
- Non-combustible degC Does not ignite. Binder may char at ~200-250 degC but does not sustain combustion
- Flame spread index
- 0 Meets NCC Specification C1.10 requirements. Does not exceed spread of flame or smoke developed indices per AS/NZS 1530.3. Source: Bradford, Fletcher, Knauf fire test data
- Smoke dev. index
- <3 Does not exceed smoke developed index per AS/NZS 1530.3. Meets NCC C1.10 requirements. Source: manufacturer fire test certificates
- Heat release rate
- <5 kW/m2 Negligible heat release. Non-combustible per AS 1530.1. Binder contributes <1% combustible content by weight
Cost & Lifecycle
Capex & lead time ·6
- Material cost (range)
- 4-25 AUD/m2 Varies by R-value. R1.5 wall batts ~$4-6/m2. R2.5 wall batts ~$6-10/m2. R3.0 ceiling ~$8-12/m2. R5.0 ceiling ~$12-16/m2. R7.0 ceiling ~$18-25/m2. Source: InsulationEasy, Pricewise Insulation, Bunnings pricing
- Material cost (per unit)
- 6-15 AUD/m2 Typical residential: R2.5 wall ~$8/m2, R4.0 ceiling ~$10-13/m2. Source: InsulationEasy 2025 guide, Canstar, Oneflare
- Lead time
- 0-3 days Standard products widely stocked at all major building supply chains (Bunnings, trade suppliers). Immediate availability for standard sizes/R-values
- Lifecycle cost
- 6-15 AUD/m2 Very low lifecycle cost. No maintenance, long lifespan, energy savings offset initial cost within 2-5 years typically
- Annual maintenance
- 0 AUD/m2/year Zero maintenance cost. No servicing required throughout lifespan
- Market availability
- Excellent Most widely available insulation in Australia. Stocked at Bunnings, all trade suppliers, specialist insulation retailers. Three major Australian manufacturers ensure consistent supply
Service life & durability ·3
- Expected lifespan
- 50-100+ years Glass wool retains thermal properties indefinitely if kept dry and uncompressed. Expected to last the life of the building. Source: ICANZ, YourHome.gov.au
- Maintenance interval
- No scheduled maintenance years No maintenance required once correctly installed. Inspect if roof space accessed or after storm damage. Check for compression, displacement, or water damage
- Warranty period
- 50-70+ years Bradford offers lifetime warranty on thermal performance. Fletcher offers 70-year warranty. Knauf offers manufacturer's guarantee. Source: manufacturer warranty statements
Layer D
Where it's used
Residential ceiling insulation
Wall cavity insulation
Acoustic insulation
Commercial building insulation
Underfloor insulation