Independent Acoustics and Noise Control Expertise Custom Audio Designs Ltd 

rockwool, rocksil acoustic mineral wool insulationrockwool, rocksil acoustic mineral wool insulationrockwool, rocksil acoustic mineral wool insulationrockwool, rocksil acoustic mineral wool insulationrockwool, rocksil acoustic mineral wool insulation

Dense fibre matting (DFM) Acoustic mineral wool


  • Acoustic Cavity infill between floor joists
  • Acoustic Cavity infill between stud walls
  • Can be used to meet New Building Regs
    (with other products)


  • Easy DIY Installation
  • Airborne noise reduction through walls & floors
  • Easy to cut
  • Low cost

22% of each slab made from recycled materials

Zero ODP and zero GWP


is particularly useful as a sound absorbing infill for the reduction of airborne noise in partition walls, between flooring joists and suspended ceilings. AMW consists mainly of silicon-oxide together with a number of other metallic oxides.
It is FAR MORE efficient for soundproofing purposes than lightweight thermal fibreglass loft insulation which should not be substituted in place of high density acoustic grade mineral wool. It is non-flammable and chemically inert and is not adversely affected by any substance it may come into contact with. Random arrangement of fibres ensures no water penetration in any direction. It is rot proof, non-hygroscopic, does not sustain vermin and will not encourage the growth of fungi, moulds or bacteria. It will not react with wired plastic or metal wall ties, brickwork or masonry.

 acoustic mineral wool

Supplied as standard in three density grades:

Our 60kg/m³ is a performance acoustic grade version. This offers the best acoustic absorption due to it's specific density (as shown on the graph below).
Our 45kg/m³ is a standard lesser performing lighter version.
We also offer a 140kg³ slab for special applications


60kg AMW, when used in a standard studwall, can increase the sound insulation performance by up to 6dB.

60kg AMW typically provides a reduction in reverberant noise levels of up to 10dB when fitted under roof constructions.

60kg AMW typically provides a reduction in airborne noise levels of up to 4dB when fitted inbetween floor/ceiling joists.

PLEASE NOTE: When fitting mineral wool slabs between joists or between frameworks you won't need as much material as the total overall area because of:
a) the thickness of the joist or frame
b) the width of the joist / frame.
c) the spacings between.
The larger the area to be treated the less packs you will need so for a small area don't worry but when you get to 100m² plus it can make a difference. As a generalisation, assuming width of a frame to be 50mm at 600mm spacings, you would have an approx. 8% excess.

If you want to upgrade a ceiling to 1 hour fire resistance without adding any extra plasterboard below then you can use rabbit wire mesh to hold the mineral wool between the joists to meet this requirement. The combination of the secured mineral wool sitting on the wire mesh, and the existing ceiling, is usually accepted by Building Control as being in compliance with the required fire resistance of a separating floor between flats. Usually the material is friction fitted tightly between the joists so you won't need any if working from above. However, it is sometimes useful to use it if working from below to prevent the material dropping back down before the plasterboard and bars are fitted.

Slab Size:1200mm x 600mm
Thickesses:25mm, 50mm, 75mm and 100mm
Weight (60kg grade): 
Density:60kg/m³ Premium Acoustic Grade
45kg/m³ Standard Grade
Thermal Conductivity:0.034W/mK
Density Tolerance:Manufactured to BS 3958 Part 5 1986

rockwool, rocksil acoustic mineral wool insulationDownload PDF COSHH

rockwool, rocksilk mineral wool insulation dense fibre matting DFM

dense fibre matting DFM
Click for Details

Dense Fibre Matting (DFM)

Slabs manufactured to a higher density than 60kg/m³ are often referred to as Dense Fibre Matting or DFM. They can provide slightly improved acoustic control and come in 100kg/m³ and 140kg/m³ densities. This product costs approx. twice that of our 60kg version and should only really be considered for specialist applications as you don't get twice the acoustic performance for double the cost !
We also supply acoustic mineral wool in a wide range of other thicknesses and densities:-
Thicknesses of 30, 40 and 60mm are also available subject to 5pack min. order.
Densities of 33kg/m³, 80kg/m³, 100kg/m³, 140kg/m³ and 200kg/m³ are also available subject to 5 pack min. order.

All information contained in these details is given in good faith but without warranty.
Custom Audio Designs reserves the right to alter the specifications of any product without notice.
©Custom Audio Designs