Most homeowners think about insulation purely in terms of temperature — keeping warm in winter and cool in summer. But insulation also plays a powerful role in controlling noise, and for many Melbourne and Victorian households, sound is just as disruptive as heat. Whether it is traffic from a busy road, noise from neighbours, or sound travelling between floors in your own home, acoustic insulation is one of the most effective solutions available.
What Is Acoustic Insulation?
Acoustic insulation is a type of insulation specifically designed to reduce the transmission of sound through walls, floors, and ceilings. While standard thermal insulation provides some level of sound dampening as a byproduct of its density, acoustic insulation is engineered to maximise noise reduction alongside — or instead of — thermal performance.
There are two types of noise that acoustic insulation addresses:
- Airborne sound refers to noise that travels through the air before passing through a surface. This includes voices, music, television, and traffic noise. Airborne sound enters through gaps, thin walls, and poorly insulated cavities.
- Impact sound refers to vibrations caused by physical contact with a surface, such as footsteps, furniture being dragged, or objects dropped on a floor above. Impact noise travels directly through the structure of the building and is particularly common in multi-storey homes and apartments.
How Does Acoustic Insulation Work?
Sound travels as a wave of energy. When that wave hits a material, some of the energy is reflected, some is absorbed, and some passes through. Acoustic insulation works by absorbing a large proportion of that sound energy within its fibres, preventing it from transmitting to the next room, floor, or outside.
The performance of acoustic insulation is measured using the Sound Transmission Class (STC) rating for airborne sound and the Impact Isolation Class (IIC) rating for impact sound. Higher ratings indicate better noise reduction. Most standard wall and floor assemblies achieve STC ratings between 30 and 40. With quality acoustic insulation installed, this can be increased significantly — often to STC 50 or higher.
Acoustic Insulation vs Normal Insulation
A common question homeowners ask is whether regular thermal insulation also provides acoustic benefits. The short answer is: yes, but not nearly as effectively.
Standard thermal insulation batts — such as glasswool or polyester — do provide some noise reduction simply because they fill a cavity that would otherwise allow sound to travel freely. However, they are engineered for thermal resistance (R-value), not sound absorption.
Acoustic insulation batts are made from denser materials, typically high-density glasswool or rockwool (stone wool), and are specifically designed to absorb a broader range of sound frequencies. The increased density means more sound energy is trapped and dissipated within the material rather than passing through the wall or floor assembly.
If noise is a primary concern for your home, standard insulation alone is unlikely to give you the results you are looking for. Dedicated acoustic insulation will deliver measurably better performance.
Where Can Acoustic Insulation Be Installed?
Acoustic Insulation for Walls
Internal walls are one of the most common applications for acoustic insulation, particularly in homes where bedrooms share walls with living areas, or where noise from adjacent properties is an issue. Installing acoustic batts within the wall cavity before the plasterboard is fitted dramatically reduces the transfer of airborne sound between rooms.
In existing homes where walls are already lined, insulation can still be retrofitted by removing and replacing plasterboard on one side of the wall, or in some cases, by adding a secondary layer of dense plasterboard with resilient channels.
Acoustic Insulation for Floors
In multi-storey homes, impact sound from the floor above is a major source of noise complaints. Footsteps, furniture movement, and children playing can all create significant disturbance to the room below. Acoustic insulation installed between the floor joists significantly reduces impact noise transmission, complementing other floor treatments such as acoustic underlay beneath hard flooring.
Acoustic Insulation for Ceilings
Ceiling insulation is one of the most effective single upgrades for noise reduction in a home, because sound from the roof space, upstairs rooms, or even heavy rainfall on a metal roof can all be dramatically reduced with the right product. Acoustic ceiling batts work alongside the ceiling's plasterboard layer to absorb sound before it penetrates the living space below.
Acoustic Insulation for New Builds and Renovations
The easiest and most cost-effective time to install acoustic insulation is during construction or a major renovation, before walls and ceilings are lined. If you are undertaking a renovation and your walls are already open, this is the ideal opportunity to install acoustic insulation alongside your thermal insulation.
Does Acoustic Insulation Have an R-Value?
Yes. Most acoustic insulation products carry both an STC/IIC rating for sound performance and an R-value for thermal performance. This means acoustic insulation provides dual benefits — it reduces noise and improves your home's thermal efficiency simultaneously.
For example, a high-density acoustic glasswool batt might carry an R-value of 2.0 while also delivering strong STC performance. In practice, this means you do not necessarily need to choose between acoustic and thermal insulation — a quality acoustic product can deliver both.
Best Acoustic Insulation Materials for Walls and Floors
The two most common materials used for acoustic insulation in Australian homes are:
- High-density glasswool batts are the most widely used acoustic insulation product in Australia. They offer an excellent balance of sound absorption, thermal performance, and cost-effectiveness. Products like Knauf Earthwool Acoustic and Bradford Acoustiwall are popular choices used widely across Melbourne and Victoria.
- Rockwool (stone wool) batts are denser and heavier than glasswool, offering superior sound absorption — particularly for lower-frequency sounds. Rockwool is often the preferred choice for home theatres, music rooms, or situations where noise reduction is the primary goal.
For most residential applications — bedrooms, living areas, internal walls between rooms — high-density glasswool acoustic batts represent the best combination of performance and value.
How Much Does Acoustic Insulation Cost in Melbourne?
Acoustic insulation cost depends on several factors, including the area being insulated, the product selected, and whether the installation is part of a new build or a retrofit into an existing home.
As a general guide, acoustic insulation for walls and ceilings in Melbourne typically ranges from $15 to $35 per square metre for supply and installation. Retrofit work — where existing wall linings need to be removed and replaced — will cost more than installation during a new build or open renovation.
The best way to get an accurate cost for your home is to request a free quote. Our team will assess your space, identify the most effective acoustic solution, and provide a clear, obligation-free price.
Acoustic Insulation Requirements in Victoria
While there are minimum acoustic performance requirements under the National Construction Code (NCC) for certain building types — particularly Class 2 buildings such as apartments — detached homes are not currently subject to mandatory acoustic insulation standards. However, this does not mean acoustic insulation is not worth installing. Noise is consistently cited as one of the biggest factors affecting liveability and mental wellbeing, and the cost of installing acoustic insulation during a build or renovation is minimal compared to the long-term benefit.
Benefits of Acoustic Insulation for Melbourne Homes
Melbourne's growing density — particularly in inner suburbs where homes are built closer together, and in areas with increasing apartment development — makes acoustic insulation increasingly important. Beyond noise reduction, the benefits include:
- Improved sleep quality. Noise disruption is one of the leading causes of poor sleep. Bedrooms insulated against external traffic noise or internal household noise can deliver dramatically better sleep outcomes.
- Greater privacy. Acoustic insulation between rooms means conversations, media, and everyday sounds are contained to the spaces where they originate.
- Reduced stress. Persistent background noise has well-documented effects on stress levels and concentration. A quieter home is a healthier home.
- Dual thermal benefit.Acoustic insulation also improves your home's thermal performance, contributing to lower energy bills alongside a quieter environment.
- Increased property value.Noise is a significant concern for homebuyers and renters. Homes with acoustic insulation are increasingly attractive in Melbourne's competitive property market.
Frequently Asked Questions
Does acoustic insulation completely soundproof a room?
No single product completely eliminates all sound. Acoustic insulation significantly reduces noise transmission but works best as part of a broader acoustic strategy that may include double-glazed windows, acoustic sealants around penetrations, and appropriate flooring treatments. For maximum soundproofing — such as in a home theatre or music studio — a specialist acoustic assessment is recommended.
Can acoustic insulation be added to existing walls?
In some cases, yes. There are specialist products and techniques that allow insulation to be injected into existing wall cavities through small holes drilled in the wall lining, which are then patched and repainted. However, the performance of injected products is generally lower than full batt installation, and not all wall types are suitable. Our team can advise on the best approach for your specific situation.
Does acoustic insulation help with outside noise?
Yes. Acoustic insulation in external walls and ceilings can significantly reduce the intrusion of road traffic noise, aircraft noise, and neighbourhood sound. For best results on external noise, acoustic insulation should be combined with double-glazed windows, as windows are typically the weakest point in the building envelope for noise control.
Is acoustic insulation the same as soundproof insulation?
The terms are often used interchangeably in marketing materials, but they refer to the same category of product. No insulation is truly "soundproof" — the correct term is sound-attenuating or sound-absorbing. Acoustic insulation is engineered to absorb significantly more sound energy than standard thermal insulation.
Can underfloor insulation reduce noise?
Yes. Polyester underfloor insulation reduces impact noise transmission between floors in raised timber homes, as well as helping to dampen airborne sound from below. See our underfloor insulation guide for more details.
Ready to reduce noise and improve the comfort of your Melbourne or Victorian home? Our team at 1 Stop Insulation provides expert acoustic insulation installation across all suburbs of Victoria. Get your free acoustic insulation quote today.