Knauf Rocksilk RS140 50mm Building Slab

The 50mm Rocksilk RS140 Knauf Rock Mineral Wool Insulation Slab is a standard-density (140kg/m3) building material that's non-combustible and engineered for diverse applications with exceptional fire performance, achieving Euroclass A1—the top classification for non-combustible products.

Sized at 1200mm x 600mm, the Knauf RS140 rocksilk insulation slab delivers outstanding thermal and acoustic properties suitable for both new builds and refurbishment work.

These slabs are odour-free, non-hygroscopic, and naturally rot-resistant. They're manufactured without CFCs or HCFCs and won't support the development of fungi, mould, or bacteria.

The 50mm Knauf RS140 unfaced insulation slab features a certified thermal conductivity (λ - lambda value) of 0.034W/mK for reliable thermal performance.

With a density of 140kg/m3, this 50mm RS140 insulation slab works well in many settings, such as internal partitions, timber and metal stud frameworks, and between timber rafters and floor joists.

The 50mm Knauf building slabs provide excellent sound absorption, delivering meaningful sound reduction benefits.

Installation is straightforward—simply cut and shape using a large-bladed knife or saw. 50mm Knauf Rocksilk RS140 insulation slab makes fitting quick and hassle-free.

Product specification

• Brand: Knauf®
• Model: 50mm Rocksilk RS140
• Thickness: 50mm
• Length: 1200mm
• Width: 600mm
• Dimensions: 1,200mm x 600mm x 50mm
• Board Coverage: 0.72m2
• Pack Coverage: 2.88m2
• Pack Quantity: 3
• R-Value: 1.45m2K/W
• Thermal Conductivity: 0.034W/mK
• Density: 140kg/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 are flexible solutions for many different uses, including pitched roof installations between rafters, intermediate floors, floor separations, internal stud partitions, and light steel frame infill. They're commonly used in OEM (Original Equipment Manufacturer) applications for producing thermal, acoustic, and fire-rated products. Thanks to their non-combustible nature, Rocksilk® Building Slabs come in various densities, from 45kg/m3 up to 140kg/m3, meeting the needs of many different projects.

Benefits

• One slab type handles multiple applications across your project.
• Factory-applied foil or tissue facing options are available, giving you flexibility for different installation scenarios.
• Made from mineral wool, these slabs offer superior sound absorption and noise control versus other common insulation materials.
• Built from rock mineral wool with a melting point above 1000°C, providing extended fire resistance compared to 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 product suits your project, or looking for a bulk discount? Get in touch by phone on +4402038839057, email sales@insulationbee, or use Live Chat—we offer competitive Knauf Loft Insulation pricing across the UK.