Technical Data | AVC – Acoustic Void Closures for Tops of Walls | Interiors | Products | Siderise

Siderise AVC – Acoustic Void Closures for Tops of Walls – Technical Data

Version: 1.00 - Release Date: December 2018


SIDERISE AVC acoustic void closures for tops of walls are a range of bespoke products designed to effectively close small apertures and voids encountered in a wide range of building conditions.  
They are produced from a range of resilient materials or laminated composites and are intended to be compression fitted into an aperture to form an efficient acoustic seal. 
Depending on the sound insulation performance required they may be employed singularly or in pairs (fitted either ‘back to back’ or commonly to each side of a central mineral fibre resilient infill). 
Three types of closure are available, designated Type 1, Type 2 and Type 3. The type number indicates how many material layers constitute the product. 
The closures are normally supplied cut to the final aperture shape but are also available in strip form (for linear gaps) or in sheet form for site cutting. 
The advanced cutting techniques employed by SIDERISE to produce the acoustic void closures permit the supply of extremely complex shapes, which can include any required internal shape pieces to be cut-out. In consequence it is normally possible to create a closure to accurately match the cross-section of any aperture.

Product Description

SIDERISE AVC acoustic void closures for tops of walls are available in the following three types: 
Type 1 closures are produced from a resilient foam material only. Commonly made from SIDERISE Lamacell closed cell foam. These closures are ideal for very small apertures or situations requiring a less demanding sound insulation performance. 
Type 1 may also be produced from SIDERISE ‘V’ series acoustic foam as a supporting backing infill for subsequent site application of an acoustic sealant/mastic to the surface.  
Type 2 and 3 closures are produced from a laminated composite combining resilient foam/s with a flexible sound barrier membrane. Type 2 closures have resilient foam to one side of the membrane only. Type 3 closures (the most common type) comprise a resilient foam layer to both sides of the barrier membrane. Type 3 closures may employ different foams to each side. 
For conditions where the closures may be partially visible, a variety of pre-applied surface finishes are available offering a range of colour options.  
The type and thickness of the closure is normally selected in conjunction with our technical department. Influencing factors include: 
  • Acoustic performance 
  • Deformation required for fitting 
  • Size & depth of the aperture 
  • Dimensional variability 
  • Shape complexity 
  • Degree of resilience/recovery required

Technical Support

Technical Services Team:


The information in this datasheet is believed to be accurate at the date of publication. SIDERISE has a policy of continuous product improvement and reserves the right to alter or amend the specifications of products without prior notice. SIDERISE does not accept responsibility for the consequences of using the products described outside of the recommendations within this datasheet. Expert advice should be sought where there is any doubt about the correct specification or installation of SIDERISE products.

SIDERISE GROUP Lady Lane Industrial Estate, Hadleigh, Suffolk, UK, IP7 6BQ T: +44 (0)1473 827695 F: +44 (0)1473 827179 E: W:

Published Version: AVC_v1_00_20200529_0009