Acoustic building regulations in Australia

by | Feb 1, 2024 | Advice & inspiration

We’ve all had to listen to our neighbours’ questionable choice of music or have wondered if more people heard a colourful conversation among friends than originally intended. There are also times when within the house, sound insulation plays an important role. Whether Mum and Dad want to watch the footy without waking up the baby, or the kids are having a sleepover, sound insulation plays a big role in providing privacy and peace.

Let’s make some noise for acoustics building regulations, and explore what you need to know and what building elements will contribute to decreasing how much sound travels in your home.

What are the acoustic building regulations in Australia?

When it comes to regulations regarding noise, there are a few you should be aware of, including:

Building Code Australia (BCA) regulations for insulation: When it comes to what you can and can’t do in construction, the building code is basically the ground zero. Chances are if what you’re planning conflicts with any of the regulations spelt out in here, you’re going to have a tough time getting an exception. These rules cover mostly insulation in your roof and walls, which also provide thermal support.

Noise Pollution Laws: Noisy neighbours are a pet peeve of everyone, hence why noise laws exist. Unlike the regulations laid out in the BCA, Noise laws can vary from council to council. Chances are that if you’re cranking up the tunes after a certain time and the party is only getting started, you’ll soon have the police around to end it.

Ventilation and lighting regulations: While not specifically about noise, ventilation and lighting regulations will influence the acoustic performance of your home.

What is the difference between airborne and impact sound?

When you look up sound insulation, you’ll come across the terms airborne sound and impact sound. Luckily, the distinction between the two is pretty straightforward. Airborne sound frequencies refer to sound travelling through the air. This includes talking, cars driving by, and basically most noises. Impact sound is much more specific as it refers to the noise made through the floor ( walking, dancing, items hitting the floor).

When testing for airborne sound, typically what will be tested is how each wall, your roof and overall home design has been constructed and how sound travels. For impact sound, many cases involve using a machine to how sound travels through the floor.

What are the different sound ratings that you need to be aware of?

Sound transmission class (STC)

Sound transmission class is a method of rating the sound insulation quality of walls in a building. Various tests and methods are carried out to measure the airborne sound insulation quality of a home and from this, a rating is determined from the results obtained.

What are the different STC ratings?

STC ratingWhat can be heard
25Soft speech can be heard and understood outside the area
30Normal speech can be heard and understood.
35Loud speech can be heard and understood
40Loud speech can be heard, but much less likely to be understood
45Most speech won’t be heard unless very loud. Privacy is more likely.
50Loud sounds can be heard but will be faint (unless incredibly loud)
60+Anything above this is considered good soundproofing. Your neighbours will be unlikely to hear anything. This isn’t the equivalent of professional soundproofing (in studios for example) but heading that direction.

What is the minimum compliant STC rating?

For most residential houses, an STC rating of between 38-42 is considered adequate. For units or townhouses, a higher STC may be necessary, as the closer vicinity will increase the likelihood of sound bleeding over. However, the best option for you will depend on your personal needs and preferences. For example, do you use power tools in your garage or practice with your band every Friday night? If so, you’ll be doing yourself and your neighbours a favour by improving your sound insulation beyond the minimum requirements. Anyone living in a noisy area (near a highway, or in the city) may want to increase their STC rating.

Our advice? Take a look at the table above and consider how private you want your home to be. If you’re someone who prefers a little more privacy or who has a noisy hobby (or needs sound insulation for recording, meetings, etc) it’s worth increasing your STC rating.

Impact insulation class (IIC)

Impact insulation class measures and quantifies how well your floorboards blocks impact sound. This is useful information for multiple-storey houses and apartment buildings. If you want tenants to avoid annoying each or everyone hearing one family member’s footsteps in the middle of the night,

The higher your IIC, the better sound insulation your floor has. How insulated your floor needs to be will depend on your situation. Just for example, a dance studio on the second floor of a building would need a very high ICC rating if they didn’t want to drive the below tenants bonkers.

Adding underlay or some sort of insulation is the best way to increase your floor’s IIC rating.

What are the different IIC ratings?

45 – the minimum rating in most cases

50-60 – the recommended rating for most residential or commercial buildings.

65- Medium quality

75+ High quality. This is required in specific situations (our dance studio from above for instance) and most homes wouldn’t need to reach this level.

What is the minimum IIC rating?

It’s recommended your floor’s IIC rating should be at least 45, though ideally it should have a rating of 50 before any carpeting is laid.

How do acoustic considerations change in different areas?

Acoustic considerations for residential spaces

To ensure the best sound insulation for your home and mimimise the chance of disturbing your neighbours (and vice versa), you need to take the specific design and location of your home into consideration. For example, a double-storey home will need to accommodate impact sound in a way a single-storey home won’t. Also, apartment buildings and townhouses are going to include homes in a much closer vicinity than individual houses. Therefore, steps will need to be made to increase sound insulation to prevent noise complaints.

Acoustic considerations for wet areas & high noise zones

When you think of the wet areas in your home – whether it be your bathroom, ensuite, toilet room, or laundry – there’s one thing they have in common. They’re all built with hard surfaces. While there is an obvious benefit to this – a carpeted bathroom is an idea too horrifying to contemplate – it does mean these rooms are especially noisy. Talk to your builder about ways to minimise echoing or sound carrying from these rooms in your house.

What are the acoustic building regulation testing requirements?

All residential and commercial properties are required to meet a minimum sound insulation rating for final approval. Testing is an important part of making sure all the steps taken to improve sound insulation have been effective while finding any weak spots that need to be addressed.

What is involved in the certification process?

A licensed professional will test your dwelling for both impact sound and airborne sound insulation. During this process, they’ll identify any areas of concern and what needs to be improved. It’s important to note that simply meeting the minimum sound insulation rating may not provide the sound insulation you actually desire. Just like how not all roadworthy cars are equal, there are ways to improve your soundproofing and noise insulation in your home.

How to stay updated with the latest acoustic building regulations?

For curiosity or as a starting point, your best place to check is the NCC itself. This is readily available online and will provide a basic idea of any new developments you need to be aware of. Any licensed contractor should be well aware of any regulations they need to follow and should be happy to answer any questions you have on the subject. Alternatively, Buildi can help you stay on top of regulations throughout your building journey.

Buildi is here to help you throughout your building journey


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