120mm Rockwool EWI External Wall Dual Density Slab

120mm Rockwool EWI External Wall DD Insulation Slab delivers premium thermal insulation for external wall insulation systems with established third-party certification.

Engineered with Rockwool Dual Density technology, these slabs feature a robust outer layer with enhanced density paired to a more flexible inner core. This construction provides an excellent surface for render and fixture installation, whilst the adaptable underside accommodates substrate variations without compromise.

When installed edge-to-edge, the slabs create a seamless thermal envelope that eliminates heat loss through joints and gaps. Rockwool's proven stone wool formulation has delivered consistent performance across European buildings for over 40 years, with documented durability extending beyond 55 years of service.

Product specification

• Brand: Rockwool®
• Model: 120mm EWI
• Thickness: 120mm
• Dimensions: 1,200mm x 600mm x 120mm
• 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®

These 120mm external wall insulation boards showcase dual density engineering with two distinct wool layers. The lower density core accommodates minor building surface imperfections, whilst the higher density exterior layer creates an ideal foundation for render application. Installation requires metal pin mechanical fixings combined with quality adhesive, with a minimum of 7 fixings per square metre recommended for optimal security.

Application

Install 120mm Rockwool Mineral Wool insulation slabs according to manufacturer guidelines covering design and installation procedures. For superior bond strength, secure boards to the substrate using mortar or adhesive alongside mechanical fixings.

Given mineral wool's increased weight, the EWI-225 Premium Basecoat is preferred over standard adhesives designed for lighter materials. Apply a thin, diluted adhesive layer to the prepared surface first. After drying, apply the basecoat and set the Fibreglass Mesh into position.

Non-combustible

Rockwool stone wool achieves the highest 'A1 – Non-combustible' rating under the European Reaction to Fire Classification System, guaranteeing no ignition risk or fire propagation contribution.

Durable

1. 120mm Rockwool DD slabs retain dimensional stability throughout the building's lifespan without shrinkage or material degradation.
2. The reinforced outer surface enables secure basecoat attachment and resists fixing over-drive.
3. Delivers exceptional resistance to wind and rain exposure during the installation phase.
4. Proven performance: 120mm Rockwool has served European EWI systems reliably for over 40 years.

Breathable

• Rockwool stone wool's open-cell structure allows water vapour to pass through whilst water-repellent fibres prevent liquid water penetration.
• Provides vapour resistance equivalent to still air conditions.

Thermal performance

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

Acoustic performance

• EWI systems using 120mm Rockwool slabs increase building envelope mass, reducing sound and vibration transmission.
• The fibrous material structure absorbs sound effectively, with test data showing up to 8 dB improvement in weighted sound reduction, Rw (substrate dependent).

Dual Density Slabs for External Walls

• Purpose-built for external wall insulation applications, Dual Density Slabs deliver premium stone wool insulation performance.
• Manufactured using ROCKWOOL's proprietary 'dual density' process, these slabs combine a higher density top layer with a more flexible core. This ensures a solid render-ready surface and secure fixture mounting, whilst the flexible base adapts to substrate variations.
• The top layer is marked 'THIS SIDE UP' for straightforward installation and correct orientation.

More Information on 120mm Rockwool External Wall DD Slab

• Manufacturer Link: Rockwool DD
• 120mm Rockwool External Wall DD Slab is a high-performance solution with diverse application possibilities.
• Explore our full Rockwool Insulation range and refine by thickness or coverage using the filters on the left. For project-specific advice or bulk pricing enquiries, contact us on +4402038839057, email sales@insulationbee, or use Live Chat for the best UK Rockwool Insulation rates.