Acoustic Insulation: Why you should never skimp on soundproofing

By Knauf Insulation APAC
September 11, 2023

What comes to mind when you hear the term acoustics? Maybe you think of your favourite concert hall or movie theatre.

We all know the importance of acoustics in these scenarios – it’s certainly not just the view that earns the best seat in the house. However, sound control is crucial in a variety of other spaces too.

Hospitals, offices, classrooms, apartment buildings, and homes located near busy roads or airports would all be considered top candidates for acoustic insulation and soundproofing. Aside from the obvious benefits of privacy and comfort, acoustic insulation and soundproofing can also lead to improved concentration and productivity, and reduced stress levels.

In this article we examine the common culprits of noise in residential applications, the basic science behind sound transmission, and provide a range of tips and examples of how to achieve long-term usability and tranquillity in your home.

What’s the real problem with noise?

The residential landscape is changing as more Australians trade in their backyards for balconies, courtyards and smaller urban blocks. And, while high density living may reduce commuting time and provide greater access to amenities, it can also exacerbate the reach and impact of noise.

Neighbourhood noise comes in many forms. Among them are road, rail or aircraft traffic, air conditioners and refrigeration units, pool pumps, dogs and other animals, TVs and sound systems, car alarms and many more. Apart from being down-right annoying, continued exposure to particular noises can affect sleep quality and poorer cognitive performance.

The science behind sound transfer

Noise can be transmitted in two ways: airborne and structure-borne. As the name suggests, airborne noise is transmitted through the air via open doors or windows, stairwells, heating or air-conditioning ducts, or pass directly through uninsulated walls, floors or ceilings. Whereas, structure-borne noise is transmitted through the structure via vibration or impact from things like foot fall, dragging of furniture, dropping cutlery or pipe noise.

Credit: Acoustic Insulation in an Internal Partition Wall Animation, Knauf Insulation UK (2019)

Understanding the difference between airborne and structure-borne noise will help you determine the best acoustic treatment or soundproofing, be it through building layout and design, acoustic insulation, construction methods and/or material type.

Sound insulation is a requirement under the Building Code, BUT…

Now that you know why noise is such a problem and some of the science behind noise transfer, let’s look at how to mitigate to create a peaceful home.

For apartments, townhouses, and semi-detached homes, thankfully sound insulation and technical requirements are mandated in the Building Code of Australia (BCA) to safeguard against excessive noise transfer. However, there are no such requirements for your average standalone residential home (yet), no matter how close they are situated.

How to avoid sacrificing long-term usability

Out of sight, out of mind, right? Wrong. Just because insulation is ultimately hidden behind walls or floors, doesn’t mean it should be first on the chopping block if cost-cutting is required. This kind of short-term view of specification and construction may result in beautiful interiors but will ultimately affect the long-term usability of the space.

The key to a beautifully finished home is the way it starts. So, the biggest tip here is to plan and budget accordingly. To demonstrate this point, here’s successful home renovator Tammie Marshall talking about how she kept insulation high on her priority list.  

Tammie Marshall’s Home Renovation Journey, The Parkway, Balgownie NSW

Credit: Molenaar+McNeice (2021)

To soundproof her home, Marshall used Earthwool® SoundShield R2.7 acoustic batts to insulate the internal walls in the kitchen, laundry, hallway, lounge room, dining room, media room and the bordering walls of her children’s bedrooms. This greatly improved the liveability of her space and meant little to no transfer in her busy family home. And here’s a fun fact: it only took her three hours to add insulation to the walls in over six rooms.

Read the case study

Private and soundproofed apartments, The Star, Gold Coast, QLD


Acoustics may have helped to reduce internal noise transfer in Tammie Marshall’s 6-bedroom family home, but what does successful soundproofing look like in a multi-residential high-rise?

To soundproof The Star, a luxury high-density mixed-use property on the Gold Coast, careful planning and construction of the internal walls were integral. With so many residents and hotel guests occupying this space it was critical to insulate the adjoining walls and ceilings to achieve a sealed inter-tenancy envelope. And, you can read more about this project and other case studies, on our case studies page.

See more projects