Independent Acoustics and Noise Control Expertise Custom Audio Designs Ltd 

Acoustic Joist CapAcoustic Resilient Joist CapAcoustic Joist CapAcoustic Resilient Joist CapAcoustic Resilient Joist Cap

Resilient acoustic joist cap for sound insulation direct to joists


  • Timber and Masonry builds
  • Part E Compliant System
  • Direct to Joist Application
  • Non specialist installation
  • -45°C to 105°C
  • Heat shrinkage less than 1% at 80°C for 96 hours


  • No Wastage!
  • No structural change over time
  • Lightweight
  • CFC, HCFC free, zero ODP
  • Very low toxic fume and smoke emissions
  • 100% recycleable
  • Moisture resistant
  • Rot proof

Direct to Joist - Acoustic Joist Caps

Part Code AC200

A superb, easy to fit, Direct To Joist System, engineered as a Part E compliant acoustic joist treatment, to save the developer time and money. It can be used in both new build and refurbishment projects for timber and masonry builds.

This product, used upside down, can also provide the resilient layer required for customers to make up their own resilient battens.

If the product is used in this manner, on a concrete floor, impact improvements in the order of: :
Delta Lw22dB with a standard batten
Delta Lw24dB with a deep batten can be expected.
Robust Details only require an improvement of Delta Lw17dB

If the product is used in this manner, on a timber floor, improvements in the order of:
Delta Rw+C;tr14dB and
Delta Lw20dB can be expected.
Robust Details only require an improvement of:
Delta Rw+C;tr13dB and
Delta Lw15dB

 acoustic joist cap direct to joist

Proven to be the most effective means of achieving superior sound attenuation, the mass of the structure is placed above the resilient layer. The product is then simply placed over the joists before the mass of the floor is added. The cap is suitable for both rough-cut and planed timber joists.

Installation Guide

  • Care should be taken to comply with all relevant Safety and Building Regulations.
  • The Joist Cap can be fitted from either above or below the joists and even before the joists are fitted.
  • The jaws of the caps are slightly tapered in to ensure a tight friction fit. Simply open the jaws and sit the cap over the joist ensuring the base is located tightly with the joist surface.
  • In all applications, our perimeter isolation strip must be used so the floating floor is fully isolated for the structural floor and walls.

Incorporating the latest changes to the Approved Document E 2003, the minimum and maximum sound insulation requirement for separating floors are as follows:



   New Build

Airborne Sound Reduction DnTw+C;tr

43dB or greater

45dB or greater

Impact Sound Pressure Level LnTw

64dB or less

62dB or less

To comply with the requirements of the  Approved Document E 2003, the Acoustic Joist Cap sound insulated separating floor has been tested in accordance with BS EN ISO 140-6:1998 and rated in accordance with BS EN ISO 717-2:1997.
It was tested at the BRE - 234174: L207-005 and L207-006

  Airbourne              Impact
Rw=63dB (Ctr-12)    Ln,w55dB
Rw+ Ctr= 51dB

On site test result samples have been:

DnT,w+ Ctr45dB47dB48dB50dB46dB

Further improvements can be made by placing 19mm Gypsum based plank over the Joist Caps before installing the 18mm T&G Chipboard.
This is highly recommended and if this is undertaken first then improved results will be in the order of:
  Airbourne              Impact
Rw+Ctr= 56dB    Ln,w50dB

DnT,w+ Ctr=48-55dB     LnT,w56-dB


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.
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