Product description

Effective external wall insulation can considerably enhance the thermal and acoustic performance of a building. The ROCKWOOL EWI Dual Density Slab is a stone wool insulation which has been specifically developed for use in external wall insulation systems. 


EWI Dual Density Slab is made using ROCKWOOL-patented dual density technology, the top layer of each slab has a distinctly higher density than the remainder of the product. This provides a firm and robust surface for the application of render or applying fixings, whilst the underside is softer to accommodate unevenness in the substrate.


As a tried and tested insulation product, EWI providers in Europe have been using ROCKWOOL in their systems for over 40 years. EWI systems incorporating ROCKWOOL slabs can add significant mass to the building envelope, preventing the transfer of noise through absorption.


The fibres in the tightly butted slabs knit together, significantly reducing heat loss that is caused by gaps between slabs. For insulation thicknesses greater than 250mm, ROCKWOOL EWI Dual Density Slabs can be installed in two layers.



Euroclass A1 non-combustible


  • Rated Euroclass A1 non-combustible, the insulation will not burn.
  • The slabs are extremely durable and resistant to adverse weather during installation.
  • The open-cell structure of ROCKWOOL stone wool makes it breathable, allowing water vapour to pass through but preventing water ingress with its water-repellent fibres.
  • EWI Dual Density Slabs boast excellent thermal performance.
  • ROCKWOOL EWI Dual Density Slabs reduce the transfer of sound and vibrations through external wall systems.
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