25mm Rockwool RWA45 Acoustic Sound Insulation Slab (11.52m2/Pack)

Product Overview

Stone wool insulation slab, measuring 25mm in thickness, designed for use in internal partitions, floors, and roof applications.

Manufactured from high-density stone wool, the slab combines excellent acoustic absorption with reliable thermal insulation and inherent fire resistance. 

Its rigid composition allows a close friction fit between studs or joists, preventing gaps that could compromise performance.

Non-combustible and classified as Euroclass A1, the slab contributes to improved fire safety within the building fabric. Its fibre structure also provides effective sound reduction, limiting noise transfer between rooms and floors.

At 25mm thick, this slab is the thinnest option in the RWA45 range. 

It is most often used in linings, cavity voids, and shallow floor or ceiling systems where only limited depth is available, but where an improvement in acoustic and fire performance is still required.

Features & Benefits

• Euroclass A1 fire classification: Non-combustible in accordance with BS EN 13501-1.
• Stone wool mineral slab: Naturally resistant to rot, fungal decay, and insect attack.
• Square-cut edges: Butt together cleanly for continuous insulation layers.
• Porous fibre structure: Absorbs sound energy, reducing noise transfer through walls and floors.
• Semi-rigid slab: Simple to shape with a knife and friction-fit between studs or joists.
• Thermal conductivity 0.035 W/m·K: Helps maintain building energy efficiency.
• Sustainable manufacture: Made from natural volcanic rock, recyclable, zero ODP/GWP.
• 25mm thickness: Ideal for lining walls where space is limited, such as drylining systems or shallow service voids.
  
  

Applications

• Stud partitions with limited cavity depth: Provides acoustic lining without excessive build-up.
• Ceiling treatments and room dividers: Adds slimline sound absorption.
• Lightweight floors between rooms: Helps reduce airborne noise in shallow voids.
• Drylined masonry upgrades: Improves acoustic resistance where depth is tight.
• Home studio soundproofing: Slim 25mm profile provides targeted high-frequency absorption for DIY acoustic panels and ceiling clouds in recording environments. 
• HMO internal partitions: Low-profile mineral wool construction provides supplementary sound dampening within narrow cavity voids to improve residential privacy. 
• Home cinema rooms: Lightweight 25mm slabs reduce internal resonance and "ringing" within metal stud tracks and decorative bulkheads.
  
  

Installation Guidance

• Precision cutting: Use a sharp insulation saw or broad-bladed knife to cut slabs slightly oversized to ensure a compressed friction fit.
• Seamless abutment: Butt all joints tightly together with no visible gaps to maintain the continuity of the fire and acoustic barrier.
• Mechanical support: Secure with appropriate netting or insulation hangers when installing in overhead applications to prevent gravity-induced movement.
• Environmental protection: Store slabs undercover and off the ground to ensure the material remains dry and free from contaminants prior to installation.
• Personal protection: Wear loose-fitting clothing, gloves, and safety goggles to minimise skin and eye contact with mineral fibres.

Soundproofing Guidance

• Mass Enhancement: Combine slabs with high-density soundproof plasterboard to significantly increase the total mass of the partition. 
• Decoupling Strategy: Use resilient bars or independent stud frames in conjunction with the slabs to prevent mechanical vibration from traveling through the structure.
• Acoustic Sealing: Apply acoustic sealant to the perimeter of the partition and around any penetrations to prevent "flanking" noise from bypassing the insulation.
• Cavity Management: Ensure the slab fills at least 75% of the cavity depth to provide optimal sound absorption and prevent internal resonance.

Compliance & Performance

• Thermal conductivity: Declared 0.035 W/m·K (EN 13162).
• Fire performance: Euroclass A1 non-combustible (BS EN 13501-1).
• Certification: CE and Key marked to BS EN 13162:2012 + A1:2015.
• Acoustic standards: Supports compliance with Building Regulations Approved Document E (England & Wales), Section 5 (Scotland), and BB93 (schools) for acoustic performance in internal and separating walls/floors.
• Sound Absorption Class: Achieves Sound Absorption Class D (aw 0.45). Ideal for reducing resonance in shallow cavities and technical enclosures.
• Marine/offshore certification: Lloyd’s Register approved as non-combustible.