Acoustic Performance of Aluminium Facade Systems

The acoustic performance of a facade is determined by the whole wall assembly, not the outer cladding alone. The cladding panel, the air cavity, the insulation, and the inner wall each play a distinct role. Specifying a cladding material in isolation tells you very little about the sound insulation the occupant will experience. What matters is how the full build-up works together - mass, decoupling, absorption, and airtightness.

What does the NCC require for facade acoustics?

NCC Volume 1 Part F5 sets the sound insulation requirements for building elements. For external walls in Class 2 and Class 3 buildings located near transport infrastructure or other significant noise sources, the wall assembly must achieve specific Rw (weighted sound reduction index) ratings. The required Rw depends on the external noise level at the facade - higher noise environments demand higher-performing assemblies.

The key point for specifiers is that the Rw rating applies to the complete wall assembly, not to any individual component. The cladding, the cavity, the insulation type and density, and the inner wall or lining all contribute to the final number. The project’s acoustic engineer determines the required assembly composition based on the site-specific noise assessment.

How does the outer cladding layer contribute?

The outer cladding in a rainscreen system serves two acoustic functions: mass and sound reflection.

interloQ has a Noise Coefficient Rating (NCR) of 0.05 and reflects 95% of incident sound energy. That means it absorbs very little sound and reflects most of it away from the building. For an external cladding layer, this is exactly what you want - the first line of defence is to keep noise out, not absorb it into the facade.

element13, at 3mm solid aluminium and 8.13 kg/m2, contributes more mass per square metre than thinner sheet cladding materials. The mass law principle is straightforward: heavier barriers transmit less sound. Doubling the surface mass increases sound reduction by approximately 6 dB. element13’s mass is a genuine advantage in the acoustic build-up.

Both products function as the outer skin of a decoupled system. They are not the whole answer - but they are an effective first layer.

Why does the cavity matter so much?

The ventilated cavity behind rainscreen cladding serves triple duty: drainage, ventilation, and acoustic decoupling.

Decoupling is the critical principle. When the outer cladding and the inner wall are not rigidly connected, sound vibrations in the outer skin are not directly transmitted to the inner structure. The air gap breaks the vibration path - the same principle used in double-stud partition walls and resilient-mount ceiling systems.

A rainscreen system using interloQ or element13 on a subframe creates exactly this arrangement. The cladding and inner wall are structurally independent except at discrete fixing points where brackets penetrate to the substrate. At typical rainscreen fixing centres (600-1,200mm), these bridges are localised, not continuous.

When acoustic-grade mineral wool or glasswool fills the cavity, it absorbs sound energy within the air gap rather than allowing it to resonate. The combination of mass (cladding), decoupling (cavity), and absorption (insulation) is the foundation of effective facade acoustics.

How does 165CW curtain wall handle acoustics?

For curtain wall, acoustic performance depends on glazing selection and frame sealing.

The 165CW unitised curtain wall system accepts insulated glazing units from 24mm to 40mm. Thicker glass - particularly laminated glass with a PVB or acoustic interlayer - delivers substantially better sound reduction. A standard 6/12/6 IGU might achieve Rw 30-32, while a laminated make-up can reach Rw 38-40 or higher.

Frame sealing is equally important. Air leakage is the enemy of acoustic performance - even a small gap in a gasket can undermine the Rw of the entire panel. The unitised approach of 165CW, where each panel is factory-assembled with gaskets and seals in place, provides more consistent sealing than site-assembled stick systems.

What design strategies work for high-noise environments?

For projects adjacent to major roads, rail corridors, or flight paths, the facade strategies that make the most difference are:

Increase insulation density in the cavity. Higher-density mineral wool (48-80 kg/m3) absorbs more sound energy than lightweight batts. For rainscreen systems, this is the simplest upgrade with the most impact.

Use laminated glass in curtain wall zones. Acoustic-rated laminated glass is the primary lever for curtain wall Rw values. The 165CW system’s capacity for up to 40mm IGUs accommodates these heavier glass make-ups.

Seal every junction. Acoustic sealant at panel joints, penetrations, and service entries prevents flanking paths that bypass the rated assembly.

Consider the inner wall. Adding mass to the inner lining - a second layer of plasterboard, or a higher-density board - often delivers more acoustic improvement per dollar than upgrading the outer cladding.

What data does Valmond & Gibson provide?

V&G supplies system-level acoustic data for its facade products - interloQ NCR and sound reflection values, element13 mass per square metre, and 165CW glazing rebate dimensions for IGU specification. This data feeds into the acoustic engineer’s modelling for the complete wall assembly.

The acoustic design itself - the required Rw, the assembly build-up, the noise assessment - sits with the project’s acoustic consultant. V&G provides the accurate product data that makes their work reliable. The practical step for specifiers is to ensure the facade supplier provides acoustic properties early enough for the acoustic engineer to model the assembly before documentation is finalised.

Last updated: 4 April 2026

Acoustic Performance of Aluminium Facade Systems