SIDERISE AVC Acoustic Void Closures for Tops of Walls (formerly Lamaphon AVC)

SIDERISE acoustic closures 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, 2 and 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 to produce the closures permit the supply of extremely complex shapes. They can also include internal cut-outs. In consequence it is normally possible to create a closure to accurately match the cross-section of any aperture.

General information

Uniclass 2015

Pr_25_71_63_60 Plastics and composite material boardsPrimary


F30/670 Head of non-loadbearing walls

G30/240 Fire resisting profile fillers

Specification data - Plastics and composite material boards

Product Reference

SIDERISE Acoustic Void Closures for Tops of Walls






Insert requirements, contact manufacturer for details.

Product Options


The type and thickness of the closure is normally selected in conjunction with Siderise's technical department. Influencing factors include: acoustic performance, deformation required for fitting, size and depth of the aperture, dimensional variability, shape complexity and the degree of resilience/ recovery required. For conditions where the closures may be partially visible, a variety of pre-applied surface finishes are available offering a range of colour options.

- 1:

  • Closures are produced from a resilient foam material only. Commonly made from Lamacell closed cell foam. Type 1 closures are ideal for very small apertures or situations requiring a less demanding sound insulation performance. May also be produced from SIDERISE ‘V’ 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.

- 2:

Type 2 closures have resilient foam to one side of the membrane only.

- 3:

Type 3 closures (the most common type) comprise a resilient foam layer to both sides of the barrier membrane. They may employ different foams to each side.

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