50mm Knauf Rocksilk RS45 Mineral Wool Slab

The 50mm Rocksilk RS45 from Knauf is a standard-density (45kg/m3) mineral wool insulation slab that delivers outstanding fire performance with Euroclass A1 classification—the highest standard for non-combustible materials.

Sized at 1200mm x 600mm, this Knauf insulation slab combines excellent thermal and acoustic properties, making it ideal for both new builds and refurbishment work.

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

With a certified thermal conductivity (λ-value) of 0.035W/mK, the 50mm RS45 unfaced slab achieves high thermal efficiency. At 45kg/m3 density, it suits applications including internal partitions, timber and metal stud work, and placement between timber rafters and floor joists.

The material excels at sound absorption, providing effective sound reduction in various settings.

Installation is straightforward—simply cut and shape using a large-bladed knife or saw for quick, hassle-free fitting.

Product specification

• Brand: Knauf®
• Model: 50mm Rocksilk RS45
• Thickness: 50mm
• Length: 1200mm
• Width: 600mm
• Dimensions: 1,200mm x 600mm x 50mm
• Board Coverage: 0.72m2
• Pack Coverage: 7.20m2
• Pack Quantity: 10
• R-Value: 1.40m2K/W
• Thermal Conductivity: 0.035W/mK
• Density: 45kg/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 work brilliantly across multiple settings—from pitched roof installations between rafters to intermediate floors, separating floors, internal stud partitions, and light steel frame infill. They're widely used in OEM (Original Equipment Manufacturer) applications for creating thermal, acoustic, and fire-resistant products. Thanks to their non-combustible nature, Rocksilk® Building Slabs come in various densities from 45kg/m3 up to 140kg/m3, covering a broad spectrum of project needs.

Benefits

• One product handles multiple applications across your project.
• Factory-applied foil or tissue facing options are available, opening up solutions for countless different uses.
• Rock mineral wool construction delivers superior sound absorption and noise reduction compared to many other common insulants.
• With a melting temperature exceeding 1000°C, the rock mineral wool core provides extended fire resistance performance versus standard alternatives.

Info

Browse our full Knauf Insulation range and refine by thickness or coverage using the filters on the left. Need advice on which products suit your project, or looking for a bulk discount? Get in touch by phone on +4402038839057, email sales@insulationbee, or use Live Chat for the best Knauf loft insulation prices in the UK.