Rocksilk Slab

Rocksilk Slab

Rocksilk Slab is high strength compression resistant and water resistant, rock mineral wool batt.

It’s fire resistance removes the need for fire barriers, giving simple quick and economical insulation for external wall insulation systems.

It is designed to thermally upgrade existing buildings some of which may be hard to treat.

  • Offers solid support to render
  • No fire stops required
  • Excellent thermal performance
  • Excellent acoustic insulation


Rocksilk External Wall Insulation Slabs are specifically for use with external wall insulation systems. The slabs can be either adhered and mechanically fixed or just mechanically fixed to the substrate then overlaid with a mesh and render system to the designers/system suppliers specification. The slabs offer a solid and robust supporting substrate for the render and no fire stops are required.

NOTE: It is the responsibility of the customer and end user to satisfy themselves, that this product is suitable for use and fit for purpose with the selected system. The end user is relying on their own expertise and judgements as to whether the insulation is suitable for their needs.


Rocksilk External Wall Insulation Slabs are manufactured in accordance with BS EN 13162:2008, EN 16001:2009 Energy Management Systems, OHSAS 18001:2007 Occupational Health and Safety Management Systems, ISO 14001:2004 Environmental Management Systems, and ISO 9001:2008 Quality Management Systems, as certified by Bureau Veritas.

Fire performance

Rocksilk External Wall Insulation Slab are classified as Euroclass A1 BS EN ISO 13501-1. In the event of a fire it will emit negligible quantities of smoke and fumes and the heat emission from the product is insignificant.


Rocksilk External Wall Insulation Slab are non-hygroscopic, odourless, rot proof, does not sustain vermin and will not encourage the growth of fungi, mould or bacteria.

Vapour resistance - resistivity

Rocksilk External Wall Insulation Slabs offer negligible resistance to the passage of water vapour and has a vapour resistivity of 7.00 MN.s.g.m.

Moisture resistance

Rocksilk External Wall Insulation Slab contain a water repellent additive to ensure that no liquid water is able to pass through the slab and reach the structure.

Handling and storage

Rocksilk External Wall Insulation Slabs are easy to handle and install, being lightweight and easily cut to size, where necessary. Rocksilk External Wall Insulation Slabs are supplied on pallets and covered with shrink-wrapped polythene for protection during transit. This packaging should not be considered adequate for long term outside protection. Ideally boards should be stored inside a building. If, however, outside storage cannot be avoided the boards should be stacked clear of the ground and covered with a polythene sheet or weatherproof tarpaulin. Boards that have been allowed to get wet should not be used.

Rocksilk Universal Slab 100D

  • August 2016

Rocksilk Universal Slab 80D

  • August 2016

Rocksilk Universal Slab 60D

  • August 2016