Acoustic Glass: How to Choose the Right Solution

Achieving Soundproofing and Comfort in Modern Developments

In commercial and multi-residential projects across New Zealand, acoustic performance is becoming a key factor in design and compliance. Whether it’s reducing road noise in city-centre apartments, homes or townhouses, managing sound in offices, or ensuring privacy in medical facilities, acoustic glass plays a critical role.

This article explores the requirements, benefits, and considerations for using acoustic glass in commercial and multi-residential builds in New Zealand, helping architects, developers, and builders make informed decisions.

Why Acoustic Performance Matters in New Zealand

New Zealand’s urban landscape is evolving, with higher-density housing, mixed-use developments, and increasing traffic contributing to greater noise pollution. The New Zealand Building Code (NZBC) Clause G6 outlines the soundproofing standards required for habitable spaces, ensuring that occupants experience minimal disturbance from external noise.

For light commercial buildings, effective acoustic control enhances productivity and comfort, while in multi-residential projects, it’s crucial for meeting compliance and occupant expectations—particularly in locations exposed to traffic, rail, or airport noise.

Note: Specific sound insulation requirements may vary depending on your project’s location or proximity to high-noise environments (e.g. airports, highways). Always confirm with your local council around the district plan requirements early in the design stages.

How Acoustic Glass Works

Unlike standard glass, acoustic laminated glass is designed to dampen sound waves, reducing noise transmission between external and internal environments. It consists of:

• Multiple layers of glass with interlayers (such as PVB – polyvinyl butyral – or specialised acoustic-grade interlayers designed to dampen vibration and sound transmission)
• Different thicknesses to disrupt sound waves at varying frequencies
• Gas-filled spaces (in double or triple-glazed units) to enhance insulation

At UNO Windows & Doors, we use laminated glass for projects where sound reduction is important. Laminated glass consists of two panes held together by a clear vinyl interlayer—usually polyvinyl butyral (PVB)—and is widely used for its soundproofing qualities. In addition to reducing airborne noise, laminated glass also helps to minimise fading from UV exposure and provides enhanced safety and security, making it a multifunctional solution for modern builds.

Acoustic Glass Ratings: Rw, Rw + Ctr and STC Explained

When choosing acoustic glazing in New Zealand, you will commonly come across three key sound insulation ratings:
Rw, Rw + Ctr, and occasionally STC. Understanding these values is essential for selecting the right windows and doors for noise control in residential and commercial buildings.

• Measures how well a building element reduces general airborne sound.
• Higher values = better sound insulation.

• Includes a correction for low-frequency sounds (e.g. traffic, trains, bass).
• Reflects real-world performance in noisy environments.

Example:
A glass type with outer 6.38mm Laminated pane, an air space of 12mm, and inner 6mm pane is rated at Rw 39 and with the correction “Ctr” factor gives a Rw + Ctr = 34.
️For roadside apartments or buildings near industrial zones, always check the Rw + Ctr value.

STC (Sound Transmission Class)

• STC is the US equivalent of Rw, based on ASTM testing standards.
• Though not commonly used in NZ, it does appear in some acoustic reports.
• STC and Rw are similar—within 1–2 points—but not always interchangeable.

Acoustic Performance and the New Zealand Building Code (NZBC)

In New Zealand, sound insulation is assessed using Rw, with benchmarks for different building types.

Key Requirements Under the NZBC Clause G6

Multi-residential buildings:

• Windows and doors that form part of a wall between dwellings must help the full assembly meet the minimum acoustic standard.

• Glazing in offices, clinics, or schools may need enhanced acoustic performance for privacy and comfort.

Construction Techniques That Matter:

• Ensure acoustic glazing is part of an airtight system
• Avoid flanking paths like unsealed junctions
• Select products that have verified acoustic performance ratings

Choosing the Right Acoustic Glass for Your Project

At UNO, we offer a range of glass configurations for sound reduction depending on your needs.

• Good:  Double glazing
• Better: Double glazing with standard laminated glass (0.38mm interlayer)
• Best:   Double glazing with special acoustic laminated glass (0.5 to 1.5mm interlayer)

The best solution depends on the type of noise you're addressing—whether it's urban traffic, industrial hum, or nearby voices and the building type. Laminated glass, especially acoustic-grade options, consistently provides the most effective performance across all situations. When specifying acoustic glass, consider:

Location and Noise Exposure:

• Urban zones or busy roads for example may require glass with Rw + Ctr ≥ 30.

Glass Type:

• At UNO, we use both standard laminated and special acoustic laminated glass specifically designed for noise reduction requirements.
• Common glass types include standard IGUs, standard laminated IGUs, and acoustic insulated glazing units (IGUs).

Balancing Acoustic and Thermal Performance:

• With H1 compliance driving energy efficiency in New Zealand, it’s important to select glass that delivers high R-values and effective noise reduction.

Compliance and Certification:

• Always ensure your chosen glazing solution meets NZBC G6 or your local district plan requirements, and is tested to the relevant standards.

How Window and Door Profiles Influence Acoustic Ratings in NZ

While glass selection plays a major role in reducing sound transmission, the frame design and joinery details are just as important. At UNO, we design our aluminium profiles with acoustic performance in mind—ensuring the entire window or door system contributes to reducing noise, not just the glazing.

Whether you're working with Rw, Rw + Ctr, or the STC rating, the profile system can make or break acoustic performance. A poorly sealed or lightweight frame will compromise the sound insulation of even the best glass.

Here’s how the profile can impact the Rw, Rw + Ctr, and STC ratings:

1. Number and Quality of Seals

• UNO’s profiles feature multiple seals to help reduce air leakage and sound infiltration.
• More seals = better airtightness = higher acoustic performance.

2. Profile Depth and Chamber Design

• Deeper profiles and multi-chamber designs create more mass and better sound insulation.
• This helps disrupt sound waves and reduces resonance through the frame.

• UNO suites are designed to accommodate laminated and acoustic glass specifically engineered for noise reduction, allowing for performance glass without compromising frame strength or aesthetics.
• For example, our UNO Thermal suite supports double glazing with acoustic-grade interlayers, balancing sound reduction with H1 compliance.

• The way profiles are installed, sealed to the building envelope, and integrated with the wall system all impact the final acoustic rating.
• At UNO, we support this with precise detailing, accurate shop drawings to ensure performance is achieved onsite—not just in theory.

See Acoustic Glazing in Action

We used acoustic laminated glass to reduce sound transfer in a multi-residential development located in Wellington. Explore how UNO's adaptable aluminium joinery provided both thermal and acoustic performance:

Case Study: Adaptable Aluminium Joinery for a Multi-Residential Project

Kapiti Terraces

Looking to dive deeper?

Explore our glass range to find the right acoustic solution for your project
Get in touch to speak with our team about your acoustic and thermal performance goals
Check out more case studies to see how we’ve supported architects and developers across NZ

In today’s building landscape, acoustic glass is no longer a luxury—it’s a necessity for high-density, mixed-use, and light commercial developments across New Zealand. By choosing the right glass solutions, builders and architects can ensure compliance, enhance occupant comfort, and add long-term value to their projects.

Whether you're working on a new townhouse development or building a commercial space, understanding acoustic glass ratings like Rw, Rw+Ctr and STC helps you choose smarter. Selecting the right configuration—be it standard laminated, double-glazed, or acoustic-grade laminated glass—ensures compliance, comfort, and better outcomes for your clients.