50mm Rockwool EWI External Wall DD Insulation Slab

50mm Rockwool EWI External Wall DD Insulation Slab delivers high-performance thermal protection for wall insulation applications with third-party certified External Wall Insulation (EWI) systems.

Manufactured with Rockwool's patented Dual Density technology, this slab features a high-density outer layer for superior render adhesion and fixture attachment, paired with a flexible inner layer that accommodates substrate imperfections. When installed with tight butt joints, the slabs interlock seamlessly to create a continuous thermal barrier that eliminates heat loss through gaps.

Specifying 50mm Rockwool DD insulation in your EWI system guarantees long-term performance and durability. Stone wool insulation of this calibre has demonstrated proven longevity, maintaining effectiveness for over 55 years in service.

Product specification

• Brand: Rockwool®
• Model: 50mm EWI
• Thickness: 50mm
• Dimensions: 1,200mm x 600mm x 50mm
• Length: 1200mm
• Width: 600mm
• Pack Quantity: Pack of 4
• Board Coverage: 0.72m2
• Pack Coverage: 2.88m2
• Pack Weight: 15.84kg
• Colour: Pale white
• Density: 110kg/m3
• Compressive strength: ≥ 10 kPa
• Tensile strength: ≥ 10 kPa
• R-Value: 0.84m2K/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 50mm Rockwool External Wall Dual Density Slab combines precision engineering with proven performance for external wall applications. These 50mm external wall insulation boards utilise a distinctive dual-layer construction: a lower-density base that flexes with minor building fabric variations, and a robust upper layer that provides an excellent substrate for render application. Installation requires metal pin mechanical fixings alongside quality adhesive, with a minimum of 7 fixings per square metre recommended for optimal security.

Application

Install 50mm Rockwool Mineral Wool insulation slabs according to manufacturer guidelines, which provide detailed design and application protocols. For superior adhesion, secure boards to the substrate using mortar or adhesive combined with mechanical fixings.

Given the substantial weight of Mineral Wool, the EWI-225 Premium Basecoat is recommended over standard adhesives designed for lighter materials. Apply a thin, diluted adhesive coat to the prepared surface first. Once cured, apply the basecoat and set the Fibreglass Mesh into position.

Non-combustible

50mm Rockwool stone wool achieves the highest 'A1 – Non-combustible' rating under the European Reaction to Fire Classification System, guaranteeing it will not ignite or support fire spread.

Durable

1. 50mm Rockwool DD slabs preserve dimensional stability throughout the building's lifespan, resisting shrinkage and deterioration.
2. The reinforced outer surface enables secure basecoat bonding and prevents fastener over-driving.
3. Delivers exceptional resistance to wind and rain exposure during the installation phase.
4. Established and reliable: 50mm Rockwool has been specified in EWI systems across Europe for more than 40 years.

Breathable

• 50mm Rockwool stone wool's open-cell structure permits vapour transmission while its water-repellent fibres prevent moisture penetration.
• Provides vapour resistance equivalent to still air.

Thermal performance

Closely fitted butt-jointed slabs allow fibres to lock together effectively, preventing thermal losses through gaps in the insulation layer.

Acoustic performance

• EWI systems using 50mm Rockwool slabs increase building envelope mass, suppressing noise and vibration transmission.
• The fibrous material enhances sound absorption, with test data showing up to 8 dB improvement in weighted sound reduction, Rw (varies by substrate).

Dual Density Slabs for External Walls

• Purpose-engineered for external wall insulation systems, Dual Density Slabs deliver a stone wool insulation solution.
• Built using ROCKWOOL's proprietary 'dual density' process, these slabs incorporate a higher-density upper layer distinct from the lower section. This creates a robust surface for render and fixture installation, whilst the softer base adjusts to substrate variations.
• For straightforward installation, the top layer is clearly labelled 'THIS SIDE UP', making the outer surface immediately identifiable.

More Information on 50mm Rockwool External Wall DD Slab

• Manufacturer Link: Rockwool DD
• 50mm Rockwool External Wall DD Slab is a premium-performance product with broad application potential.
• Browse our complete Rockwool Insulation range and refine by thickness or coverage using the filters on the left. For project-specific advice or bulk purchase quotations, contact us on +4402039519012, email sales@insulationbee.co.uk, or use our Live Chat service – we offer the lowest UK Rockwool Insulation prices.