Knauf Rocksilk RS80 50mm Building Slab

The Knauf Rocksilk RS80 50mm Mineral Wool Insulation Slab is a standard-density (80kg/m3) rock wool building material that delivers outstanding fire performance, achieving Euroclass A1 classification—the highest non-combustible rating available.

Sized at 1200mm x 600mm, this Knauf RS80 rocksilk insulation slab provides excellent thermal and acoustic properties suitable for both new builds and refurbishment work.

These slabs are odourless, non-hygroscopic, and rot-proof. They're manufactured without CFCs or HCFCs and resist fungal, mould, and bacterial growth.

With a certified thermal conductivity (λ value) of 0.034W/mK, the 50mm Knauf RS80 unfaced insulation slab delivers reliable thermal efficiency across diverse applications.

Produced at 80kg/m3 density, this 50mm RS80 slab works well for internal partitions, timber and metal stud work, and installation between timber rafters and floor joists.

The Knauf building slabs feature impressive sound absorption capabilities, delivering meaningful sound reduction performance.

Installation is straightforward—simply cut and shape using a large-bladed knife or saw. The 50mm Knauf Rocksilk RS80 slab combines practical handling with reliable performance.

Product specification

• Brand: Knauf®
• Model: 50mm Rocksilk RS80
• Thickness: 50mm
• Length: 1200mm
• Width: 600mm
• Dimensions: 1,200mm x 600mm x 50mm
• Board Coverage: 0.72m2
• Pack Coverage: 4.32m2
• Pack Quantity: 6
• R-Value: 1.45m2K/W
• Thermal Conductivity: 0.034W/mK
• Density: 80kg/m3
• Colour: Brown
• Material: Rock mineral wool
• Fire Classification: Euroclass A1
• Vapour Resistivity: 5.00MNs/g.m.
• Fire Reaction: Non-combustible
• Building Regulations: Class '0'
• Finish: Unfaced
• Shipping method: Articulated Vehicle ǀ Courier
• Applications: Floor ǀ Wall ǀ Roof ǀ Partitions
• Foil faced: No
• ECOSE Technology: Yes
• ETA Notification: Yes
• Features: Thermal and Acoustic Insulation Performance
• Manufacturer: Knauf Rocksilk®

Made to order Facings

For a factory applied foil or tissue facing please request a quotation using the website form or by calling our agents. We do offer single side or double side foil/tissue facings.

Applications

50mm Rocksilk Building Slabs suit a wide range of building scenarios, from pitched roof work between rafters to intermediate floors, separating floors, internal stud partitions, and light steel frame infill. These slabs are frequently used in OEM (Original Equipment Manufacturer) applications for creating thermal, acoustic, and fire-rated products. Thanks to their non-combustible nature, Rocksilk® Building Slabs are produced across a range of densities from 45kg/m3 to 140kg/m3, meeting the needs of many different projects.

Benefits

• One slab type addresses multiple building applications.
• Factory-applied foil or tissue facing options are available, expanding the scope of suitable applications.
• Rock mineral wool construction delivers superior sound absorption and noise reduction compared to many alternative insulation products.
• With a melting temperature exceeding 1000°C, rock mineral wool provides extended fire resistance performance relative to other common insulants.

Info

Browse our full Knauf Insulation range and use the left-hand filters to narrow by thickness or coverage. For advice on product suitability for your project or to request a bulk discount quotation, contact us on +4402038839057, email sales@insulationbee, or use our Live Chat service—we offer competitive Knauf Loft Insulation pricing across the UK.