200mm Rockwool EWI External Wall Dual Density Slab

200mm Rockwool EWI External Wall DD Insulation Slab delivers professional-grade thermal insulation for external wall insulation systems with third-party certification and proven performance credentials.

Manufactured with Rockwool's proprietary Dual Density technology, these slabs feature a reinforced outer layer with superior density and a flexible inner core. This dual-layer construction creates a robust surface ideal for render and fixture installation, whilst the softer underside accommodates substrate variations and imperfections.

When installed with tight joints, the slabs interlock to form a complete thermal barrier, eliminating heat loss through gaps and ensuring consistent insulation performance across the entire wall surface.

Specifying 200mm Rockwool DD insulation in an External Wall Insulation (EWI) system provides building owners with confidence in long-term thermal performance. Stone wool insulation from Rockwool delivers exceptional durability, with proven effectiveness spanning over 55 years of real-world use.*

Product specification

• Brand: Rockwool®
• Model: 200mm EWI
• Thickness: 200mm
• Dimensions: 1,200mm x 600mm x 200mm
• Length: 1200mm
• Width: 600mm
• Board Coverage: 0.72m2
• Colour: Pale white
• Density: 110kg/m3
• Compressive strength: ≥ 10 kPa
• Tensile strength: ≥ 10 kPa
• R-Value: 1.39m2K/W
• Thermal Conductivity: 0.036W/mK
• Material: Molten volcanic rocks
• Profile: Square edge
• Temperature resistance: up to 1000ºC
• Fire Classification: A1 Non-combustible
• Shipping method: Articulated Vehicle ǀ Courier
• Applications: External Wall Insulation Systems
• Features: Thermal and Acoustic Insulation Slab
• Manufacturer: ROCKWOOL®

The 200mm Rockwool External Wall Dual Density Slab combines precision engineering with practical installation benefits for external wall applications. These 200mm external wall insulation boards incorporate a distinctive dual-density design with two wool layers of varying densities: a lower-density base layer that accommodates minor substrate variations, and a higher-density upper layer that provides an excellent foundation for render application. Installation requires both mechanical fixings and high-performance adhesive, with a minimum of 7 fixings per square metre recommended for secure attachment.

Application

Install 200mm Rockwool Mineral Wool insulation slabs in accordance with manufacturer guidelines, which detail design specifications and installation procedures. For optimal adhesion, secure boards to the substrate using mortar or adhesive combined with mechanical fixings.

Given the substantial weight of Mineral Wool products, we recommend the EWI-225 Premium Basecoat for application instead of standard adhesives suited to lighter materials. Apply a thin, diluted adhesive layer to the prepared surface first. Once cured, apply the basecoat and set the Fibreglass Mesh into position.

Non-combustible

200mm Rockwool stone wool achieves the highest fire rating of 'A1 – Non-combustible' under the European Reaction to Fire Classification System, meaning it will not ignite or support flame propagation.

Durable

1. 200mm Rockwool DD slabs retain dimensional stability throughout the building's lifespan, resisting shrinkage and material degradation.
2. The dense outer layer supports secure basecoat application and prevents fastener over-driving.
3. Demonstrates excellent resistance to wind and rain exposure during the installation phase.
4. Time-tested solution: 200mm Rockwool has delivered proven performance in European EWI systems for more than 40 years.

Breathable

• 200mm Rockwool stone wool's open-cell structure permits water vapour transmission, whilst water-repellent fibres prevent moisture penetration.
• Provides vapour resistance equivalent to still air conditions.

Thermal performance

Tightly butt-jointed slabs allow fibres to interlock effectively, preventing thermal losses through joints and gaps in the insulation layer.

Acoustic performance

• Building envelopes incorporating 200mm Rockwool slabs benefit from increased mass, which reduces sound and vibration transmission.
• The fibrous material contributes to sound dampening, with testing showing sound reduction improvements of up to 8 dB weighted, Rw (subject to substrate conditions).

Dual Density Slabs for External Walls

• Purpose-engineered for external wall insulation systems, Dual Density Slabs deliver a comprehensive stone wool insulation solution.
• Manufactured using ROCKWOOL's proprietary 'dual density' process, these slabs incorporate a higher-density upper layer than the core material. This creates a stable surface for render and fixture installation, whilst the flexible lower layer adapts to substrate variations.
• For ease of installation, the upper layer is clearly marked 'THIS SIDE UP', making it simple to identify the correct orientation.

More Information on 200mm Rockwool External Wall DD Slab

• Manufacturer Link: Rockwool DD
• 200mm Rockwool External Wall DD Slab is a premium-performance product offering multiple application possibilities.
• Explore our full Rockwool Insulation range and refine by thickness or coverage using the filters on the left. For guidance on product suitability for your specific project or to request a quantity discount quotation, contact us by phone on +4402038839057, email sales@insulationbee, or use Live Chat - Competitive UK Rockwool Insulation Pricing.