Home > Companies > Custom Audio Designs Ltd > Acoustic Joist Cap

Easy to fit, direct-to-joist system, engineered as a Building Regulations (E&W) Approved Document E compliant acoustic joist treatment. The jaw of the caps are slightly tapered to ensure a tight friction fit.

When used upside down, it can also provide the resilient layer required when making resilient battens.

It can be used in both new build and refurbishment projects for timber and masonry builds. Used to achieve good sound attenuation, the mass of the structure is placed above the resilient layer. It is then placed over the joists before the mass of the floor is added. The cap is suitable for both rough-cut and planed timber joists.


  • No wastage.
  • No structural change over time.
  • Lightweight.
  • CFC and HCFC-free.
  • Zero Ozone Depletion Potential (ODP).
  • Very low toxic fume and smoke emissions.
  • Moisture resistant.
  • Rot-proof.


  • Timber and masonry builds.
  • Direct to joist application.
  • Non-specialist installation.

Standard product features

Size (l x w):

2000 x 50 mm.


12 mm.


30 kg/m³.

Acoustic performance:

Varies depending on application, refer to manufacturers data sheets.



Flanking strip must be used to fully isolate the floating floor from the structure.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-70-45/320 Acoustic batten cradles

Product specification

An important note about specifying



Custom Audio Designs Ltd


+44 (0)1730 269572

Product reference

Acoustic Joist Cap


[L-profile flanking strip]

Manufacturer details

5 Ridgeway Office Park,
Bedford Road,
Hampshire, GU32 3QF
Tel +44 (0)1730 269572
Fax +44 (0)1730 265846
NBS Plus