Expanded Polystyrene (EPS) or Mineral Wool — When to choose which and why

EPS or mineral wool? Both provide insulation, but they react differently to fire, moisture, and sound. The choice depends on what you are building. ## Comparison - Lambda (insulation performance): EPS 0.031–0.045; mineral wool 0.032–0.040 — a tie for high-quality products. - Fire resistance: mineral wool is non-combustible (Class A1), EPS is self-extinguishing but will melt. - Acoustics: mineral wool provides significantly better noise insulation — it is the go-to choice for ground floors near busy streets. - Moisture: EPS absorbs almost no moisture; mineral wool can become damp without a vapor barrier. - Price: EPS is about 30–50% cheaper for the same level of insulation. ## When to choose which - Standard facade: EPS 100, 15–20 cm — the most sensible budget choice. - Attic: mineral wool — for superior acoustics and fire safety. - House near a busy road: mineral wool on the street side, EPS for the rest (mixing is standard practice). - Garage and boiler room: exclusively mineral wool. The material is 30% of your success — the other 70% is the system and the installation. Find a team with a manufacturer's certificate on LocalTrader.