WLS 035 blown-in glass wool insulation
Insulation boards
Plaatisolatiematerialen
Plattendämmstoffe
Mats for thermal insulation
Mattenisolatiematerialen
Mattendämmstoffe
Loose-fill and blow-in insulation materials
Stort- en inblaasisolatiematerialen
Schütt- und Einblasdämmstoffe
Speciality products
Speciale producten
Spezialprodukte
Eigenschaften
Glass wool is a non-combustible insulating material and, like all mineral wool insulation, offers sound-insulating properties in addition to its good thermal insulation properties. Due to the fibrous structure of glass wool, the flakes can mat together, thereby preventing the material from settling. Consequently, when installing core insulation, slightly more and larger drill holes may be required in the wall in order to blow in the glass wool flakes.
For cavity wall insulation, a water-repellent glass wool blow-in insulation material is used. When fibre-based glass wool blow-in products are used, there is no sagging. In addition to core insulation, blown-in glass wool insulation materials are also used for insulation in timber-frame construction, in sloping roofs, timber-beam ceilings or for retrofitting insulation in party walls.
Rohstoffe und Herstellungsverfahren
Raw materials: up to 80 per cent recycled glass, dolomite, quartz sand, soda, limestone, small quantities of water-repellent agents and recycled production residues
The raw materials are melted at approx. 1400 °C and the melt is defibrated using the nozzle-spinning process. Once the glass-like melt has passed through the melting furnace, it is fed into so-called defibration machines and defibrated. The defibration process works in a similar way to the production of candy floss.
The fibres are then sprayed with water-repellent agents to impart water-repellent properties. Manufacturers
Technical Specifications
Property | Unit | Parameters | ||
|---|---|---|---|---|
| Core insulation, e.g. Supafil Cavity Wall | Timber panel construction, e.g. Supafil Timber Frame | Top floor slab, e.g. Supafil Loft | ||
| Thermal conductivity λR | W/(mK) | 0.035 | 0.035 | 0.040 |
| Bulk density ρ | kg/m³ | 30–40 | 30–40 | 20–23 |
| Heat capacity c | J/(kgK) | 840 | 840 | 840 |
| Building material class | -- | A1 | A1 | A1 |
| Water vapour diffusion resistance μ | -- | 1 | 1 | 1 |
| Primary energy content | kWh/m³ | 210 | 210 | 210 |
| Water-repellent properties | -- | yes | N/A | N/A |
Glass wool insulation materials are recyclable. To be melted down, they must be sorted by type and free from foreign matter. The glass wool product can also be extracted whilst sorted by type and installed in new cavity spaces, thereby allowing it to be reused. Ground-up mineral wool can also be used as an additive in the manufacture of bricks, fibre-cement boards and roof tiles. Otherwise, it is disposed of in landfill.[i]
In recent years, mineral wool manufacturers have developed take-back and recycling systems, through which several thousand tonnes of mineral wool from construction sites and demolition projects are now recycled into new mineral wool every year. Recycling capacities are being continuously expanded.
DIN EN 14064-1 and EAD 040729-00-1201 in conjunction with DIN 4108-10, Table 16 (Application-specific requirements for blown-in mineral wool insulation materials)
Legal provisions:
A blow-in insulation material is only considered an insulation material within the meaning of building regulations if it has been installed by specialist contractors who have been trained in its handling by the respective manufacturer and are listed on a register. If installed by a DIY enthusiast themselves, the material is insulating but, from a legal perspective, does not constitute insulation. In the event of damage (e.g. fire), there could be problems with insurance claims. Furthermore, any subsidies are forfeited for structures in which self-installed blow-in insulation has been used. Even in the case of ‘KfW-x buildings’ or new builds, these insulation materials must not be included in the calculations made by energy consultants or architects.
Gesundheit und Ökologie
In Germany, only mineral wool products – namely rock wool and glass wool – that pose no risk to health and have been approved in accordance with the Hazardous Substances Ordinance (GefStoffV) and the Chemicals Prohibition Ordinance (ChemVerbotsV) may be placed on the market and installed. These products bear the RAL quality mark ‘Mineral Wool Products’, which is awarded by the Gütegemeinschaft Mineralwolle e.V.[ii] The Gütegemeinschaft monitors and checks compliance with the certification requirements. The KEYMARK quality mark also certifies the high quality of mineral wool insulation materials.
From an environmental perspective, the use of recycled glass, the material’s good compressibility and, consequently, the reduced packaging and transport requirements are positive factors. Furthermore, manufacturers are already operating waste-free and working to reduce CO₂ emissions during the production process.
[i] ENVIRONMENTAL PRODUCT DECLARATION in accordance with ISO 14025 and EN 15804+A2 for mineral wool insulation in the low bulk density range, FMI Fachverband Mineralwolleindustrie e.V., 29 June 2023: https://www.der-daemmstoff.de/wp-content/uploads/2023/07/Mineralwolle-Daemmstoff-im-niedrigen-Rohdichtebereich_EN15804A2.pdf (accessed on 11 December 2025)
[ii] Gütegemeinschaft Mineralwolle e.V.: https://www.ral-mineralwolle.de (accessed on 3 July 2024)
- affordable
- Use of recycled glass
- low resource consumption due to low bulk density
- non-combustible
- Good sound insulation
- Low packaging and transport costs due to high compression
- No sifting
- Product suitable for core insulation is water-repellent
- recyclable
- With core insulation, a minimum gap of 4 cm between the wall shells is required
- A greater distance and larger drill holes may be required, as the flakes tend to mat together