70mm Rockwool EWI External Wall DD Insulation Slab

70mm Rockwool EWI External Wall DD Insulation Slab delivers reliable thermal protection for external wall insulation systems with established third-party certification.

Manufactured using Rockwool's patented Dual Density technology, these slabs feature a reinforced outer layer with superior density paired with a softer, more flexible inner layer. This construction provides an excellent surface for rendering and fixture installation, whilst the adaptable underside accommodates substrate variations.

When installed with tight butt joints, the slabs lock together to form a complete thermal envelope, eliminating heat loss through gaps and thermal bridging.

Specifying 70mm Rockwool DD insulation in an External Wall Insulation (EWI) system gives building owners and occupants assurance in sustained insulation performance. Stone wool insulation delivers proven longevity, with documented performance extending beyond 55 years.*

Product specification

• Brand: Rockwool®
• Model: 70mm EWI
• Thickness: 70mm
• Dimensions: 1,200mm x 600mm x 70mm
• Length: 1200mm
• Width: 600mm
• Pack Quantity: Pack of 3
• Board Coverage: 0.72m2
• Pack Coverage: 2.16m2
• Pack Weight: 15.84kg
• 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 70mm Rockwool External Wall Dual Density Slab combines precision engineering with proven performance for external wall applications. These 70mm external wall insulation boards employ distinctive dual density construction with two wool layers of varying density: a lower density base accommodating minor surface imperfections, and a higher density upper layer creating the perfect foundation for render application. Installation of 70mm Rockwool external wall insulation boards requires both mechanical metal pin fixings and strong adhesive bonding. A minimum of 7 fixings per square metre is recommended for correct installation.

Application

Installation of 70mm Rockwool Mineral Wool insulation slabs must follow manufacturer guidance, including design specifications and application procedures. For optimal adhesion, secure boards to the substrate using mortar or adhesive combined with mechanical fixings.

Given the substantial weight of Mineral Wool, we recommend applying the EWI-225 Premium Basecoat instead of standard adhesive formulated for lighter materials. Apply a thin, diluted adhesive coat to the prepared surface first. After curing, apply the basecoat and set the Fibreglass Mesh.

Non-combustible

70mm Rockwool stone wool achieves the highest fire rating of 'A1 – Non-combustible' under the European Reaction to Fire Classification System, guaranteeing it will not ignite or accelerate fire spread.

Durable

1. 70mm Rockwool DD slabs retain dimensional stability throughout the building's lifetime, resisting shrinkage and material degradation.
2. The reinforced outer surface supports secure basecoat installation and prevents fastener over-driving.
3. Delivers superior resistance to wind and rain exposure during the installation phase.
4. Established and reliable: 70mm Rockwool has been a proven choice in EWI systems throughout Europe for more than 40 years.

Breathable

• 70mm Rockwool stone wool's open-cell structure permits water vapour transmission, whilst its water-resistant fibres prevent moisture penetration.
• Provides vapour resistance equivalent to still air.

Thermal performance

Slabs installed with tight butt joints allow fibres to interlock efficiently, preventing heat loss through gaps and weak points in the insulation layer.

Acoustic performance

• EWI systems using 70mm Rockwool slabs increase building envelope mass, reducing sound and vibration transmission.
• The fibrous material enhances sound absorption, with test results showing up to 8 dB improvement in weighted sound reduction, Rw (depending on substrate type).

Dual Density Slabs for External Walls

• Engineered specifically for external wall insulation systems, Dual Density Slabs provide a stone wool insulation option.
• Manufactured using ROCKWOOL's proprietary 'dual density' process, these slabs incorporate a higher density upper layer with a softer base. This delivers a robust surface for rendering and fixture attachment, whilst the flexible lower layer adapts to substrate variations.
• For ease of installation, the top layer is marked with 'THIS SIDE UP', making it simple to identify the correct orientation.

More Information on 70mm Rockwool External Wall DD Slab

• Manufacturer Link: Rockwool DD
• 70mm Rockwool External Wall DD Slab is a premium performance product offering flexible installation options.
• Browse our full range of Rockwool Insulation products and refine by thickness or coverage using the filters on the left. For advice on product suitability for your project or to request a bulk discount quotation, contact us on +4402038839057, email sales@insulationbee, or use Live Chat - Competitive UK Rockwool Insulation Pricing.