Rock Mineral Wool - Knauf Insulation Rocksilk® Flexible Slab

Knauf Insulation Rocksilk® Flexible Slab


Multi-Application, Ground floors, Internal floors, Separating floors, Pitched roofs at rafter level, Internal walls / partitions, Light steel frame walls, Timber frame walls


Rock Mineral Wool


Rocksilk® Flexible Slab is a rock mineral wool slab, designed for use in multiple thermal and acoustic applications as well as the fire protection of a loft conversion floor.

It is non-combustible with the best possible Euroclass A1 reaction to fire classification, and is manufactured using our unique bio-based binder, ECOSE® Technology.


  • Single slab can be used for multiple applications.
  • Tested to achieve up to 60 minutes fire resistance when used in the floor of a loft conversion.
  • Engineered to adapt to minor imperfections in the substrates and friction fits between studs, joists and rafters.
  • Enables existing ceilings to be retained on a loft upgrade whilst meeting building regulations.
  • Manufactured from mineral wool which provides the best levels of sound absorption and reduction compared to other mainstream insulants.

For historical versions of product documentation, or documents relating to any discontinued products, please contact us with your requirements at [email protected].  




Thickness (mm) Length (mm) Width (mm) Thermal Conductivity (W/mK) R-value (m²K/W) Euroclass Reaction to Fire Classification Quantity per pack Packs per pallet
40 1200 600 0.037 1.05 A1 14 12
50 1200 600 0.037 1.35 A1 12 12
60 1200 600 0.037 1.60 A1 10 12
70 1200 600 0.037 1.85 A1 8 12
90 1200 600 0.037 2.40 A1 6 12
100 1200 600 0.037 2.70 A1 6 12
140 1200 600 0.035 4.00 A1 3 12

Certification & Memberships

Eurofins Gold Eurofins Gold
Euroclass A1 Reaction to Fire Classification Euroclass A1 Reaction to Fire Classification
Green Guide Rating A+ Green Guide Rating A+
CE Marking CE Marking
Robust Details Robust Details
EN 15804 EN 15804
Made in Britain Made in Britain
DECLARE 'Red List Free' DECLARE 'Red List Free'

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