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Rockwool RW3 50mm

Performance: Will vary due to featuring in acoustic systems.

Dimensions: 1200mm x 600mm x 50mm

Weight: 20kg

For: Homes and workplaces.

Compliance: Compliant with both Part E Building Regulations (England, Wales, Northern Ireland and the Republic of Ireland).*

Installation: Will vary depending on which system it features.

Where: Wor all cavities found between floor joists, stud frame walls and ceilings.

Universally recognised throughout the world of soundproofing, commonly used as part of an acoustic system, or combined with additional acoustic materials such as our MuteClip®. There is currently a shortage on Rockwool RW3, RWA45, Knauf RS60 and RS45 within the UK, please do contact us before orders so we can indicate stock availability.

More Information

Specialist Acoustic Mineral Wool for Part E Building Regulations Compliance

Rockwool PROROX SL930 Acoustic Mineral Wool (RW3) (60kg per m3) is high-density acoustic mineral wool that is used to treat the ‘open spaces’, or cavities, between flooring joists, stud-frame walls and ceilings. It is an open-fibrous material that when sound comes in to contact with, turns that sound energy into heat, essentially reducing the sound. Although, it is not used as a standalone and should always be used as part of a system where these open spaces exist. Acoustic Mineral Wool helps to prevent Flanking Transmission through the open cavities, and the sound amplifying. Any acoustic system fitted without it will not achieve its full acoustic performance and may fall short of expectations.

Acoustic Mineral Wool has a greater density than thermal wool comparisons which is evident in their slab appearance, the reduction in acoustic insulation for this material in the form of an NRC (Noise Reduction Coefficient) which differs for each thickness, what this essentially means is that it is an absorptive material as opposed to a dense, heavy soundproofing product. You will find all acoustic systems that Acoustic Mineral Wool is featured in, which there is most, by selecting the ‘Systems’ tab above.


  • Essential for all soundproofing systems with joists or stud-frames.
  • To be used in cavities to provide optimum soundproofing performance for all systems
  • Slab dimensions 1200mm x 600mm x 50mm (8 per bale – 5.72m2)
  • Other thicknesses include; 100mm, 75mm and 30mm
  • Euroclass A1 fire rating
  • Always leave an air gap to ensure full performance a minimum of 10mm
  • A 3-5 day lead time can be expected with Rockwool, please call ahead for availability

Rockwool RW3 Pack Quantities

  • 100mm
  • 75mm
  • 50mm
  • 30mm
  • 4 Slabs (2.88m2)
  • 6 Slabs (4.32m2)
  • 8 Slabs (5.72m2)
  • 15 Slabs (10.8m2)
60kg is the measured density of the product in cubic meters – it is a lightweight sound insulation material that is easy to cut, easy to lay and most of all, essential for sound proofing projects installing to stud framing, joists or in any cavities. Use gloves and eye protection and keep the area ventilated during and after installation.
The 50mm thickness is best used to help treat stud frameworks and to use between flooring joists to treat cavities, leaving them untreated can lead to the remaining sound passing through and resonating in these areas. You will also want to avoid using a thicker size than the air gap provided and aim to have at least a 10mm air gap – using a 100mm thickness in a 50mm cavity will lead to compression of the acoustic mineral wool and a direct path of sound to travel through, degrading the effectiveness of any sound proofing system.
In almost all acoustic systems that look to soundproof over frameworks or help suspend materials like our MuteClip System or our MuteMat Systems. In soundproofing you use Rockwool acoustic mineral wool is to treat the cavities found in between frameworks and flooring joists to reduce sound from reflective around inside them, and then resonating. It is important to note that this is a lightweight, fibrous material and this means that sound will pass through it – so it is not effective in reducing airborne nor impact noise issues as a standalone product.
Acoustic Mineral Wool is fibrous, and this means that fibres can be released into the air when exposed, which is why you place them in cavities and not to use as an exposed sound absorption panelling. We offer a vast range of sound absorption materials where you can be as creative as you like, a variety of colours and 3D structures can all tailored to your space.
We have found that a bread knife usually makes for an excellent cutting tool if this is unavailable – a large pair of scissors will also work well.
The fibrous element can lend to slight irritation of the skin; those with sensitive skin may find a slight redness appear while installing, the use of gloves and protective eyewear is recommended.

Installation Guide

Although acoustic insulation used here is not toxic or hazardous, when installing it does release small dust particles, so do use gloves, goggles or face mask.

Measure the depth of the cavity first, or if you know the stud depth you are using, make sure that you choose a depth of Acoustic Mineral Wool that allows for a 10mm air gap on either side.

The reason you leave this air gap is to avoid compressing the fibrous properties between the two partitions you are soundproofing, for example, do not use a 50mm depth in a 30mm gap.

Acoustic Mineral Wool is easy to cut with large scissors, or we found a bread knife to be a great tool here.

Cut the slab a little larger than the stud or joist gap to friction hold, or use a form of wiring to hold it in place.

Sound insulation advice for Part E

Soundproofing Floors
Soundproofing Floors
Soundproofing Designs for Party Floors to achieve compliance with Part E of the Building Regulations.
Soundproofing Walls

Soundproofing Walls

Soundproofing Designs for Party Walls to achieve compliance with Part E of the Building Regulations.

Related Products

Rockwool RW3 30mm

Rockwool RW3 100mm
Knauf RS60 50mm
Knauf RS60 100mm

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