Rocksilk® EWI Slab is a high-performance rock mineral wool insulation solution designed specifically for external wall insulation (EWI) systems. Holding a BBA Agrément Certificate (24/7271), this slab is ideal for application to the exterior of masonry or concrete walls in both new build and retrofit projects. The slabs can be either adhered and mechanically fixed or solely mechanically fixed, offering flexibility in installation.
With a Euroclass A1 reaction to fire rating, Rocksilk® EWI Slab is fully non-combustible, removing the need for fire barriers and ensuring peace of mind for specifiers and installers. Manufactured with a water-repellent additive, the slabs help prevent moisture ingress, while their mineral wool composition delivers excellent thermal and acoustic performance. Rocksilk® EWI Slab is compatible with both silicone and mineral render systems, providing versatile design options.
Key Benefits:
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BBA-certified (24/7271) for EWI use on external masonry/concrete walls in residential and commercial buildings
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No fire breaks required thanks to Euroclass A1 fire rating
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Also available in a denser, stronger version – Rocksilk® EWI Slab Plus
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Compatible with silicone and mineral renders for flexible finish options
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Water-repellent additive for superior moisture resistance
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Excellent sound absorption and reduction properties
Technical Data
| Product Code |
264382 |
| Board Size |
90mm x 600mm x 1200mm (0.72m²) |
| Material |
Rock Mineral Wool |
| Certification |
BBA Agrément Certificate 24/7271 |
| Material |
Extruded Polystyrene (XPS) |
| Thermal Conductivity (λ) |
0.036 W/mK |
| Thermal Resistance (λ) |
1.65 m2K/W |
| Tensile Strength |
10 kPa |
| Compressive Strength |
30 kPa |
| Reaction to Fire (Euroclass) |
Euroclass A1 (non-combustible) |
| Water Absorption (long-term) |
WL(P) < 3 kg/m² (per BS EN 12087) |
| Water Vapour Resistance |
Vapour resistivity 5.00 MN·s/g·m (negligible resistance) |
| Density |
≈ 100 kg/m³ |
| Application |
External Wall Insulation – masonry or concrete substrates |
For external wall insulation works, EWI Pro strongly recommends obtaining a full EWI Pro system specification, particularly where warranties or compliance are required.
Individual products purchased without an EWI Pro system design do not constitute a warranted EWI system.
Insulation products may be used independently for repairs, maintenance, flooring, or other non-EWI applications.
