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External Wall & Facade Lamella Slabs

ROCKWOOL® External Wall Slabs and Façade Lamella Slabs are used as the insulation layer within External Wall Systems for both refurbishment and new build construction. External Wall DD Slabs are suitable for installation on flat surfaces and façades. Lamella is also suited to curved surfaces.

mineral wool
  • Outstanding thermal and acoustic properties

  • Exceptional fire performance – Non combustible

  • Relies on entrapped air to provide a stable thermal performance

  • Is rated as having Zero Ozone Depleting Potential and Global Warming Potential. Relying on entrapped air for its thermal properties, we are proud to say that External Wall and Facade Lamella Slabs do not contain (and have never contained) gases that have an ozone depleting potential (ODP) or global warming potential (GWP)

  • Compressible rear face of External Wall DD Slabs are able to accommodate small imperfections in the existing building surface

  • External Wall DD slabs provide tighter contact with the existing façade and optimises thermal performance

  • Easily cut and shaped

  • Dimensionally stable

  • Options for installation on flat and curved surfaces with Facade Lamella recommended for installation to curved surfaces

  • Fibres knit together at horizontal and vertical board joints to eliminate thermal bridging

  • Open cell structure allows the facade to breath-minimising the risk of condensation

  • Recyclable- guaranteed that ROCKWOOL® insulation waste returned to ROCKWOOL® is recycled and reused in our manufacturing process.

Insulation Options:

External Wall DD Slab

External Wall DD Slabs use patented Dual Density technology to provide a high density top surface to a lower density subsurface. The lower density will accommodate slight imperfections in the fabric of the bulding and the higher density top layer is the ideal surface for the application of renders. The top (high density) layer is branded ‘ROCKWOOL® THIS SIDE UP’ should face away from the wall substrate.

  • Sized 1200mm x 600mm, External Wall DD Slabs are available in thickness of 50mm to 250mm in 10mm increments.

  • External Wall DD Slabs are adhesive and mechanically fixed.

  • N.B. 30mm & 40mm thicknesses (usually used for reveals) are manufactured as High Density (HD) Slabs.


External Wall HD Slabs

ROCKWOOL® also manufacture a HD slab to meet those specifications which may call for a higher density external wall slab. Thermal conductivity is λ(90/90)= 0.038W/mK at 30mm & 40mm thickness and 0.039W/mK at thicknesses greater than 40mm.
Sizes: HD slabs are 1200mm x 600mm with a thickness range between 30mm and 200mm


Facade Lamella Slabs

Facade Lamellas are 1000mm x 200mm and are available in thickness from 30mm to 300mm in 10mm increments. Facade Lamella can be both adhesively fixed and mechanically or adhesively fixed only. Adhesively fixed only systems are ideal for substrates that are problematic for mechanical fixings. 30mm & 40mm thicknesses are High Density slabs used in the main for insulating at window reveals.



External Wall DD Slabs and Facade Lamella Slabs are non-combustible and have a European Reaction to Fire Classification of A1 to EN 13501-1. These products will not contribute to the growth of a fire including the fully developed stage.


Thermal Conductivity

  • External Wall DD Slab λ(90/90) = 0.036 W/mK

  • Façade Lamella Slab λ = 0.040 W/mK



Relying on entrapped air for its thermal properties, we are proud to say that ROCKWOOL® insulation does not contain (and has never contained) gases that have ozone depleting potential (ODP) or global warming potential (GWP). ROCKWOOL® therefore complies with the relatively modest threshold of GWP<5 included in documents such as the Code for Sustainable Homes. ROCKWOOL® boasts a state of the art recycling facility based in Bridgend, South Wales, allowing contractors and builders to recycle ROCKWOOL® insulation and reduce their requirement for landfill. From off-cuts to new build projects as well as ROCKWOOL® waste from refurbishment or decommissioning work, we offer a total recycling solution. ROCKWOOL® waste is also accepted at our recycling hub in Nottingham. If you have ROCKWOOL® waste that you do not wish to send to landfill, please contact us to discuss your individual requirements.


External Wall DD Slabs have a superior acoustic performance when compared with rigid cellular plastic foam insulants. The fibrous structure of ROCKWOOL® provides excellent acoustic absorption characteristics. When used on masonry and steel framed walls, with render finishes, they can improve the weighted sound reduction by 5 to 8dB.


External Wall DD Slabs and Façade Lamella Slabs offer no sustenance to vermin and do not encourage the growth of fungi, moulds or bacteria.

Health and Safety

A material safety data sheet can be downloaded from the ROCKWOOL® web site

Handling and Storage:

ROCKWOOL® slabs should be handled with care. They should be stored indoors or under waterproof covering.

Quality Assurance:

ROCKWOOL® Limited operates a Quality Management System which complies with the requirements of BS EN ISO 9001 : 2008 and is registered by BSI-QA under Certificate No. FM 02262.

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