The introduction of blown-in insulation made from mineral wool could revitalize a neglected market segment: ISOVER (Saint-Gobain) is launching Topdec and Integra, two products that are specifically positioned against established cellulose and EPS blown-in insulation materials. While cellulose dominates existing building renovations and EPS (Styrofoam) scores with its low weight, ISOVER relies on the fire protection properties and dimensional stability of mineral wool – arguments that are particularly decisive for multi-story buildings and strict fire protection requirements according to DIN 4102-1.

Technical Specifications: Lambda Values and Processing Properties

Topdec is primarily aimed at roof insulation in existing buildings and new construction. According to the manufacturer, thermal conductivity is λ = 0.035 W/(m·K), a value that competes with common cellulose insulation (λ = 0.038–0.040 W/(m·K)) and is sufficient for typical renovation projects under the GEG (Building Energy Act). For use in cavities, hollow spaces, and roof slopes, flowability is crucial: mineral wool in loose form tends to settle, which is why ISOVER claims to have developed a modified fiber structure that should allow cavity filling without significant compression.

Integra, on the other hand, targets core insulation in double-leaf masonry and timber frame buildings. The higher bulk density – specific values are not disclosed, typical blown-in mineral wools range from 30–60 kg/m³ – is intended to improve sound insulation performance, an advantage over lightweight cellulose products. For planners who must meet sound insulation requirements according to DIN 4109, this could be a relevant argument, especially since double-leaf constructions with core insulation are often used in terraced houses and apartment buildings.

Fire Protection and Standard Compliance: Building Material Class A1 as a Competitive Advantage

The central differentiating factor compared to organic insulation materials lies in fire classification: mineral wool achieves building material class A1 (non-combustible) according to DIN EN 13501-1, while cellulose is classified as B2 (normally flammable) or B-s2,d0, and expanded polystyrene (EPS) typically achieves B1 or B-s1,d0. In buildings with increased fire protection requirements – such as those under the Model Building Code for building classes 4 and 5 – this can simplify planning, as additional fire protection measures can be omitted.

For renovation projects in protected heritage structures, where historic wooden beam ceilings and tight hollow spaces often don't allow for subsequent installation of fire protection boards, A1-classified blown-in insulation offers significant planning advantages. Approval according to DIN EN 14064-1 (blown-in insulation made of mineral wool) confirms suitability for these applications, though planners should pay attention to project-specific evidence: EPD data (Environmental Product Declaration) and specific fire protection reports must be provided by the manufacturer.

Processing Logistics: Machines, Compaction, and Material Requirements

Blowing in mineral wool requires adapted technology: unlike cellulose, which is often transported with simple screw feeder systems, glass fibers require gentle dosing to prevent fiber breakage. According to its own specifications, ISOVER recommends specialized blow-in machines that operate at reduced pressure (approximately 0.5–1.0 bar) – a detail that processors must consider in their calculations, as longer processing times can increase labor costs.

For a typical single-family house with 140 m² of roof area and 20 cm insulation thickness (U-value approximately 0.16 W/(m²·K) according to GEG requirements), with λ = 0.035 W/(m·K), the material requirement is approximately 28 m³ of blown-in insulation. At an assumed bulk density of 40 kg/m³, this corresponds to approximately 1,120 kg of material. Market-standard prices for mineral wool blown-in insulation are 8–12 €/m³ (ex works), while cellulose is 6–9 €/m³ – a surcharge of 20–30% that planners must weigh against the fire protection and sound insulation advantages.

Sustainability and CO₂ Balance: Mineral Wool vs. Renewable Raw Materials

In direct sustainability comparison, mineral wool lags behind bio-based alternatives: manufacturing requires melting temperatures of 1,400–1,500 °C, which increases the CO₂ footprint to 400–600 kg CO₂-eq/t (source: typical EPD values for glass wool). Cellulose from recycled waste paper achieves 50–150 kg CO₂-eq/t, wood fiber insulation achieves 200–350 kg CO₂-eq/t depending on binder. However, ISOVER emphasizes recyclability: mineral wool can theoretically be completely remelted and respun, supporting the circular economy – an argument that gains importance given the tightened EU Green Deal requirements.

The actual recycling rate in demolition, however, is below 10%, since contaminated mineral wool (e.g., with bitumen or adhesive) cannot be separated in a pure stream. Planners who opt for EPD-certified products should check whether ISOVER provides updated environmental product declarations for Topdec and Integra according to EN 15804, documenting the end-of-life process.

Market Context: Competition with Rockwool and Cellulose Providers

With this product launch, Saint-Gobain is responding to two trends: first, demand for A1 insulation materials in multi-story timber construction is growing, where fire protection according to Eurocode 5 imposes strict requirements. Second, ISOVER is positioning itself against ROCKWOOL, which is already established with stone wool blown-in insulation. The market for blown-in insulation in Germany is estimated at approximately 250,000 t/year (source: industry reports), with cellulose holding about 60% market share, and mineral wool currently only 15–20%.

Profitability for processors depends heavily on the application: in existing building renovations, where basement ceilings and cavities are insulated without demolition, blown-in insulation is unrivaled – here processing speed is paramount. In new construction, however, they compete with mat and board insulation, which often cost less for the same U-value. ISOVER addresses this contradiction with the argument of seamless cavity filling, which minimizes thermal bridges – an advantage that can be demonstrated in thermographic testing according to DIN EN 13187.

Practical Scenarios: Renovation vs. New Construction

For renovation projects in old buildings – for example, in timber-framed buildings with historic cavities or double-leaf brick facades – Topdec offers a practical solution: blowing is done through drill holes (Ø 30–40 mm), which are sealed after completion. The U-value of a 12 cm thick core insulation (λ = 0.035 W/(m·K)) is approximately 0.28 W/(m²·K), which narrowly misses the GEG requirement of 0.24 W/(m²·K) for existing buildings, but can be combined with additional internal insulation. Here ISOVER competes directly with perlite and aerogel blown-in insulation, which achieve better lambda values (λ = 0.018–0.022 W/(m·K)) but cost ten times as much.

In new construction of timber frame buildings, Integra focuses on combining thermal and sound insulation: a 24 cm thick cavity insulation achieves U = 0.14 W/(m²·K) and simultaneously improves the weighted sound reduction index R'w by approximately 2–3 dB compared to cellulose insulation – an advantage that in terraced houses and semi-detached houses can justify the investment. However, planners should note that the diffusion-open building method (μ-value of mineral wool: 1–2) requires careful vapor barrier planning according to DIN 4108-3 to avoid condensation damage.

The market launch of Topdec and Integra shows that ISOVER – despite positive growth in the construction crisis – takes competitive pressure in the insulation material segment seriously. Whether mineral wool blown-in insulation can establish itself against established cellulose systems ultimately depends on planners' willingness to value the fire protection and sound insulation advantages – and on processors' ability to implement the specific processing requirements economically.