Strength band
not structural; binder and facing matter for handling
Numbers below are bands used by working engineers, not live quotes. Tensile note: not structural; binder and facing matter for handling.
Fire performance in this atlas is editorial. Real projects need the assembly report.
Mechanical
Stiffness
Modulus follows chemistry and orientation — not the marketing nickname.
Toughness
Crack growth, not peak stress, retires most real parts.
Fatigue / creep
Cyclic and time-dependent damage dominate certificates issued on static coupons.
Hardness / hand
Indentation, drape or compressive class — whichever the trade actually measures.
Thermal
Conductivity
λ ~0.032–0.040 W/m·K typical batts — Mineral wool is used as insulation.
Service temperature
Melting / softening / decomposition band: softens ~1000 °C class (stone).
Expansion
Joints and clearances must follow the expansion class of Mineral wool, not of steel-by-habit.
Thermal mass
Density 20–150 kg/m³ products sets how fast a section changes temperature.
Ageing of λ
Foams, VIPs and moist batts drift; quote aged values.
Electrical
Conductor or dielectric
Mineral wool is generally a dielectric or semiconductor film, not building wire.
Static / EMI
Fillers and moisture change resistivity more than brochures admit.
Standards language
IACS, volume resistivity or dielectric strength — pick the quantity the job uses.
Fire
Reaction to fire
Typical declared class: A1. This is not a universal passport.
Resistance vs reaction
Euroclass is reaction. EI/R ratings are assemblies — boards, coats, cavities.
Melt-drip / char
Mineral wool tends to char or stay inorganic rather than melt-drip like commodity olefins.
Smoke / toxicity
CO, HCN, HF or fibres — the species depend on chemistry. Name the test (ISO 5659, EN 45545, NFPA 1971).
If a salesperson quotes a single “safety score”, ask which standard, which thickness, which year.
Keep exploring
More in Thermal
🧽
Polyurethane foam
The low-λ organic foam of fridges and buildings — excellent insulation, a fire design problem unless PIR and coverings are honest.
Overall 46 📦Vacuum insulated panel
A sealed vacuum sandwich — λ around 0.004–0.008 W/m·K until the envelope leaks.
Overall 44 🕯️Phase-change material
Latent-heat packets that flatten temperature swings — not a substitute for λ insulation, a complement.
Overall 36