Rockwool External Wall Dual Density Slab

Brand: Rockwool
£26.24 Incl. VAT
£26.24 Incl. VAT (regular price)
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    Rockwool External Wall Dual Density Slab

    Rockwool External Wall Dual Density Slabs are a premium insulation board composed of mineral wool, which is a very similar material to fibreglass. While fibreglass is made up of thousands of glass fibres, Rockwool is made from molten volcanic rocks. The material is produced by heating the volcanic rock within a large furnace, then spinning it into fibrous strands and compressing it into boards. As a vapour-permeable insulation material, the boards are ideal for use with a breathable thin coat render such as EWI Pro's Silicone Render. Rockwool is the insulation material of choice for architects and builders alike. Another benefit of Rockwool Dual Density insulation boards is that they are completely non-combustible. The insulation boards have achieved a Euroclass rating of A1 for non-combustibility - this is the highest rating that an insulation material can achieve. With fire-safety being so topical and of such importance, the Rockwool insulation goes extra lengths to offer complete assurance against the threat of fire. With the ability to withstand temperatures of up to 1,000ºC (1,800ºF), the Rockwool insulation helps to effectively contain and prevent the spread of fire. At the same time, the stone wool will not produce any toxic smoke or emissions. This makes Rockwool insulation the ideal product for areas of urban development, and for high-rise structures. When you choose Rockwool External Wall Dual Density Slabs for your external wall insulation system, you also gain the added benefit of acoustic insulation. The open porous structure of the stone wool means that the boards are able to absorb and reduce the impact of sound, enabling homeowners to enjoy a comfortable, quiet internal environment. In highly populated areas or for homes and buildings that are within close proximity to road traffic, the benefits of this are unrivalled. The Rockwool External Wall Dual Density Slab is specially crafted to be ideal for external wall insulation. The boards are called 'dual density' because they are made up of two different density layers of wool; a low density for the subsurface and high density for the exterior. The lower density will accommodate slight imperfections in the fabric of the building, and the higher density top layer is the ideal surface for the application of renders. Rockwool external wall insulation boards require metal pin mechanical fixings as well as a strong adhesive to tie them to the wall (a minimum of 7 fixings are required per m2).

    Preparation

    Use netting on scaffolding as well as a protective rainproof covering to reduce exposure to elements such as rain and excess sunlight.

    Application

    Rockwool Mineral Wool insulation slabs should be installed in accordance with the manufacturer’s instructions – these include guidelines on design and other aspects of application. We recommend the boards are fixed to the substrate with mortar/adhesive and mechanical fixings to ensure maximum adhesion. Because of the greater weight of Mineral Wool, we advise that you use the EWI-225 Premium Basecoat for the application rather than a standard adhesive, which is used on lighter insulating materials. Apply a light, watery based coat of the adhesive to your prepared surface initially. When it is dry, apply the basecoat, then sink in the Fibreglass Mesh.

    Storage

    Shelf life: please see the manufacturer’s date of expiry. Keep in a dry place, in the original undamaged packaging, avoid excess heat or UV light exposure.

    Thicknesses and Coverage Rates

    50mm (Pack of 4 Slabs) 2.88 m²
    60mm (Pallet of 40 Slabs) 28.8 m²
    70mm (Pack of 3 Slabs) 2.16 m²
    80mm (Pack of 3 Slabs) 2.16 m²
    90mm (Single Slab) 0.72 m²
    100mm (Single Slab) 0.72 m²
    110mm (Single Slab) 0.72 m²
    120mm (Single Slab) 0.72 m²
    130mm (Pallet of 18 Slabs) 12.96 m²
    140mm (Pallet of 18 Slabs) 12.96 m²
    150mm (Pallet of 16 Slabs) 11.52 m²
    160mm (Pallet of 16 Slabs) 11.52 m²
    170mm (Pallet of 12 Slabs) 8.64 m²
    180mm (Pallet of 12 Slabs) 8.64 m²
    190mm (Pallet of 12 Slabs) 8.64 m²
    200mm (Pallet of 12 Slabs) 8.64 m²
    210mm (Pallet of 12 Slabs) 8.64 m²
    220mm (Pallet of 10 Slabs) 7.2 m²
    230mm (Pallet of 10 Slabs) 7.2 m²
    240mm (Pallet of 10 Slabs) 7.2 m²
    250mm (Pallet of 10 Slabs) 7.2 m²

    Technical Data

    Product Type Stone Wool (Rock Mineral Wool)
    Application External Wall Insulation Systems
    Thermal Conductivity (λ) 0.036 W/mK
    R-Value 50mm: 1.39 m²K/W, 100mm: 2.78 m²K/W
    Fire Classification Euroclass A1 (EN 13501-1) – Non-combustible
    Tensile Strength ≥ 10 kPa (outer layer)
    Compressive Strength ≥ 10 kPa
    Water Vapour Resistance (μ) Typically < 1 (highly breathable)
    Moisture Resistance Water repellent
    Density Approx. 105 kg/m³ (inner) / 175 kg/m³ (outer)
    Slab Dimensions 1200mm x 600mm
    Thickness Range 50mm – 250mm
    Weight Approx. 3.8–7.6 kg per slab (based on 50–100mm)
    Facing No Facing
    Product Standard EN 13162:2012+A1:2015
    Declaration of Performance (DoP) UK-WER-0129
    CE Certificate Number 0751-CPR-393.0-02
    Compatibility Suitable with EWI systems using mechanical fixings and render finishes

    Frequently asked questions

    Dual density slabs feature two layers with different compressive strengths: a denser outer layer for impact resistance and a softer inner layer for easier fixing and improved conformity to uneven surfaces. In contrast, high density slabs have a uniform density throughout, offering consistent rigidity but less flexibility during installation. Dual density provides an optimal balance of durability and workability, particularly ideal for external wall insulation systems.

    Yes, it is specifically designed for use in external wall insulation systems with render finishes. The rigid outer layer provides a stable base for render application, while the breathable structure supports moisture regulation.

    Rockwool Dual Density Slabs offer a thermal conductivity of approximately 0.036 W/mK, making them highly effective at reducing heat loss through external walls.

    Yes, Rockwool Dual Density Slabs are non-combustible with a Euroclass A1 fire rating, offering the highest level of fire resistance for insulation materials.

    It is suitable for a wide range of building types, including residential, commercial, and high-rise properties. However, it’s important to ensure the insulation system is properly specified for the building’s structure and exposure conditions.