JCW Underfloor Standard Cavity System

This system is a lower cost alternative to our premium underfloor cavity acoustic solution and will still give a significant improvement to the sound insulation of timber suspended floors.

It also combines two acoustic products, the first of which is positioned below the floor in the joist cavity, after the original flooring has been lifted, and the second which can then be added either directly to the newly exposed joists to become in effect the new floor surface, or laid as an extra layer on top of the original flooring, should you choose to replace it.

Below the floorboards JCW Acoustic Easy Fit Mineral Wool Slab, a highly effective mineral wool slab, is fitted to the cavity spaces between the joists, providing better acoustic performance against airborne sound penetration than traditional mineral wool insulation,

Then our chipboard based JCW Acoustic Deck 37C is fitted direct to the joist after the existing floorboards have been removed, or alternatively fixed on top of the replaced original flooring if preferred.

The solution helps significantly reduce airborne noise from above and below.

This acoustic decking complies with Part E of the Building Regulations (England & Wales) and Section 5 (Scotland) for both impact and airborne noise.


JCW Acoustic Easy Fit Mineral Wool Slab

This acoustic grade rock mineral wool slab absorbs airborne sound in the cavity spaces of walls as well as floors and ceilings, significantly improving acoustic performance. It acts as a sound layer inside the cavity between the joists, absorbing airborne sound and helping reduce reverberation. This flexible acoustic grade mineral wool is supplied in packs of easy to handle 1200mm x 600mm slabs, in a variety of thicknesses. It’s an efficient noise absorber which easily outperforms standard mineral wool insulation because at 45kg per cubic metre in weight, it is more than twice the density!

Its use only adds minimally to the overall mass of the structure. It is supplied un-faced.

Its combination of acoustic, thermal and fire retardant properties helps explain why this product is widely used as a key insulating material across the building industry in all types of constructions.

The JCW Acoustic Easy Fit Mineral Wool Slab complements the acoustic decking used in this solution by not just absorbing airborne sound, but also by reducing the hollow sound that can sometimes occur in unfilled cavities

JCW Acoustic Easy Fit Mineral Wool Slab – Excellent sound absorption in the floor cavity

  • Quick, economical and flexible to install in wall, floor and ceiling cavities
  • Practical and easy to cut to different stud centres
  • Fire retardant classified as Euroclass A1 to BS EN ISO 13501-1
  • Eco friendly made from a formaldehyde-free binder and rapidly renewable bio-based materials which is 70% less energy intensive than petroleum based chemicals. Free from CFCs, HCFCs and any other material with ozone depletion potential. Classified as Zero ODP and Zero GWP
  • Natural containing no artificial dye or colouring
  • Durable odourless, rot proof, non hygroscopic. Does not sustain vermin and will not encourage the growth of fungi, mold or bacteria. Arrangement of fibres ensures no water penetration in any direction.


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    Technical Specifications

    JCW Acoustic Easy Fit Mineral Wool Slab Specification

    Composition: Non-combustible rock mineral wool, defined as mineral wool in BS: 3533: 1981 and manufactured in accordance with BSI Quality Assurance Standard BS EN ISO 9001: 2000.
    Slab Size: 1200mm x 600mm
    Thickness options: 25mm/50mm/75mm/100mm
    Density: 45 kgs per m3
    Fire Classification: Euroclass A1 to BS EN ISO 13501-1
    Eco friendly: Zero ODP and Zero GWP
    Vapour resistivity: 7.00 MN s.g.m.
    Thermal R Value: 1.25 m2K/W

    Slabs per pack

    Thickness (mm)
    Slab Size (mm) Slabs per pack
    Area per Pack (m2)
    100 1200 x 600 5 3.6
    75 1200 x 600 6 4.32
    50 1200 x 600 10 7.2
    25 1200 x 600 20 14.4

    JCW Acoustic Deck 37C

    This is a high performance acoustic deck, specially designed for direct to joist fitment after the existing timber floor has been removed. It provides enhanced acoustic performance without the need for a new timber sub floor to be laid, making it ideal for refurbishment projects or where there are floor to ceiling height issues because it is only 37mm thick. The product is light to handle and easy to install and consists of a 22mm layer of tongued and grooved chipboard upper layer laminated to a lower resilient layer comprising a 9mm inner of polyurethane foam sandwiched between two outer layers of acoustic mat.

    The t&g edging ensures the decking has a snug fit, eliminating gaps between boards to enhance acoustic performance and acting as a superb under floor for all types of final floor finish.

    JCW Acoustic Deck 37C: Product summary and benefits

    • Easy to install high acoustic performance system direct to joist after existing timber floor is removed
    • No need for a new sub floorMinimal loss of ceiling to floor height
    • Ready for final floor finish to be laid once installed
    • Complies with Building Regulations Part E (England & Wales) and Section 5 (Scotland)
    • Suitable for 400mm and 600mm joist centres
    • Non load bearing walls can be built directly off the floating floor

    Acoustic Performance and Building Regulations

    Impact Performance L’nw 52 dB
    Airborne Performance Rw + Ctr55 dB

    JCW Acoustic Deck 37C Specification

    • Composition: 22mm P5 t&g chipboard laminated to an acoustic resilient layer (comprising a 9mm inner of reconstituted polyurethane foam sandwiched between 2 outer layers of 3mm acoustic mat made from recycled rubber)
    • Board/sheet size 37mm thick x 2400mm long x 600mm wide
    • Weight 31kgs per board

    JCW Ancillary Products required for this acoustic solution

    • JCW Waterproof PVA Adhesive
    • JCW Acoustic Sealant and Applicator Gun
    • JCW Perimeter Edging Strip

    At a glance guide to what you’ll need for the JCW Underfloor Standard Cavity Soundproofing System

    You can quickly work out how much soundproofing products and ancillaries you’ll want if you use this at a glance guide to help you calculate things. Check the square metre dimensions of the area to be treated and apply to the tables below

    Floor Area in m2
    JCW Deck 37C (sheets/ coverage m2) JCW Acoustic Slab JCW Perimeter Edging Strip
    JCW Acoustic Sealant JCW Waterproof PVA Adhesive
    1 1 (1.44) TBD 1 Roll 1 1
    2 2 (2.88) TBD 1 Roll 1 1
    3 3 (4.32) TBD 1 Roll 1 1
    4 3 (4.32) TBD 1 Roll 1 1
    6 5 (7.20) TBD 1 Roll 1 1
    8 6 (8.60) TBD 1 Roll 1 1
    10 8 (11.52) TBD 1 Roll 1 1
    15 11 (15.84) TBD 1 Roll 2 2
    20 15 (21.60) TBD 1 Roll 2 2
    25 18 (25.92) TBD 1 Roll 2 2


    Note: Where the initials TBD appear, please discuss your project with one of our sales advisors to determine the exact amount you will need.


    DIY Installation Guide for the JCW Underfloor Standard Cavity Soundproofing System

    General Preparations:
    Because JCW Acoustic Easy Fit Mineral Wool Slab is made from mineral wool, this product can cause irritation to the skin, so suitable protective wear like gloves and eye goggles should always be used when handling and working with it. Always ensure the area you are working in is weathertight before installing the floor. Also, JCW Acoustic Deck 37C should only be installed when conditioned to its environment and ideally its moisture content should be the same as might be expected when installed and in use. It should always be stored flat, taking care not to damage the tongue and groove edges.
    Step 1: Take up all of the existing floor coverings like carpets, laminates or vinyls etc.
    Step 2: Now remove the skirting boards, taking care not to damage them so that you can replace them afterwards without needing to buy new ones.
    Step 3: Now lift and remove the existing floor surface to expose the joist cavity. Remove any debris or dirt which may have accumulated using a brush and pan. Again take care not to damage the flooring if you wish to replace it afterwards.
    Step 4: Now insert the JCW Acoustic Easy Fit Mineral Wool Slab into the cavity. The slab can be easily cut to any size/shape using a sharp long bladed knife. The knife should be re-sharpened often to maintain performance.
    Step 5: Multiple layers can be used where space allows, for increased performance.
    Step 6: Position JCW Perimeter Edging Strip at the base of all perimeter walls. This will eventually be trapped in place by the acoustic deck.
    Step 7: If you do not want to replace the previously raised floorboards, you can now lay the JCW Acoustic Deck 37C sheets (direct to joist) with the long edge across the joists. Short joints should be staggered and supported by noggins where the joints do not coincide with the floor joists. To ensure the tightest possible jointing, each tongue and groove should be glued with JCW Waterproof PVA Adhesive.
    Step 8: Remove tongues and grooves from the edges of JCW Acoustic Deck 37C where it meets the wall perimeter. This will ensure only square cut edges butt up to the JCW Perimeter Edging Strip.
    Step 9: Fill any unavoidable gaps with JCW Acoustic Sealant. This will help maintain the acoustic integrity of the solution.
    Step 10: The JCW Perimeter Edging Strip is then folded over the chipboard and trapped under the skirting board when it is refitted – the excess can then be trimmed flush to the skirting with a sharp work-knife.
    Step 11: The completed floor should not be walked on for at least 48 hours to ensure the adhesive has cured.
    Step 12: Before any overlay floor finishes are fitted it is essential that the entire floor is perfectly flat, clean and dry. Where necessary it is ok to sand off any raised points before covering the floor. Vinyl sheet flooring or carpet may allow an image of the board joints to telegraph through the overlay used and will tend to show small irregularities in a floor surface to a greater extent than thicker, patterned or textured finishes. To avoid this problem completely, a 6mm butt-jointed plywood overlay should be fitted, staggering the joints so as not to coincide with those of the chipboard beneath.
    Note: Before using any adhesives or other bonding materials to fix your choice of final floor finish to the JCW Acoustic Deck 37C, please refer to the manufacturers recommendations and guidance. Use only those products recommended by the manufacturer that are considered suitable. When in doubt, contact the manufacturer.

    Professional Installation Service available

    For customers who need or prefer it, Soundproofyourhome offers a professional acoustic installation service across the UK.

    Our skilled and experienced tradesmen understand acoustic materials and how to fit them quickly and correctly.
    The result is a cost effective service and peace of mind about the acoustic integrity of your project. Contact us today for a free quotation.

    Soundproofyourhome is the domestic market operations division of JCW Acoustic Supplies Ltd, the UK’s leading manufacturer and distributor of soundproofing, sound insulation and sound absorbing products.

    Sound advice from Soundproofyourhome:

    Contact us today and tell us more about the noise problems you are experiencing. Our friendly, helpful advisors will offer you the most appropriate acoustic solutions available to meet your acoustic needs and budget from our comprehensive range.

    We believe talking about your situation and offering sound advice based on our vast experience in the acoustics business is a more reliable way of solving your noise problem than simply taking your order or selling “off the screen”, as some companies do.

    And if you are in any doubt about issues associated with soundproofing, like weight of materials, structural strength or meeting Building Regulations, then please talk to us – we’ll be happy to help.