3.9 Building Code of Australia | Owners Corporation Network

3.9 Building Code of Australia

The Building Code of Australia’s (BCA) general objective is to safeguard occupants from illness or loss of amenity as a result of undue sound being transmitted. They comprise a uniform set of technical provisions for the design and construction of buildings – structure, fire, health and amenity etc. The relevant sections refer to Class 2 – a building containing 2 or more dwelling units (eg: flats, apartments). Guidelines for the sound insulation and acoustic properties of walls between adjoining units in multi-residential buildings are set out in Building Code of Australia - Volume 1. Class 2 - 9 dwellings, Section F - Health and Amenity, Part F5 Sound Transmission & Insulation.  

“If you have a by-law in your building which forbids or restricts flooring that doesn’t properly insulate noise transmission, you are halfway there. If it specifies the Australian Building Standard for noise transmission, you may have a problem and have to depend on Strata Law (see below). Australian Building Standards are a joke when comes to apartments and those that apply to flooring seem to have been designed for people whose feet never actually touch the ground.”Jimmy Thomson, Flat Chat

The BCA was changed in 2005 to increase airborne sound insulation requirements for walls and floors and introduced impact sound insulation requirement for floors. It also allowed on-site testing as an option for verifying performance. Why it changed?

  • Increase in apartment living in recent years – corresponding increase in complaints. Occupant expectations were not being achieved. The number of complaints from owners indicate that the recommended amount of sound insulation required for internal walls is too lenient.
  • The new code would also need to recommend a minimum requirement for 'impact sound insulation' of floors. Currently there is no requirement, because the code assumes that carpet will be used as a general floor covering, ignoring the fact that homeowners are turning to hard floor coverings such as polished boards and ceramic tiles.
  • In some cases resulting from specific construction / workmanship issues. The code only applies to so-called airborne sounds, not structure-borne or impact sounds.
  • BCA minimum standards – NOT appropriate for higher quality developments
  • BCA changed to reflect modern lifestyle and appliances. The code only applies to internal walls, not the external walls of a house. This means there are no controls over loud street noises entering a house or loud party noises leaking to the outside. The code assumes that the noisiest areas in a house are the kitchen, laundry and bathroom. Today it is the living room, with powerful entertainment systemsand hard floor surfaces, and is probably the noisiest in the house.

However, if your building was built prior to the 2005 changes, you will be stuck with the pre-2005 standards. This does not mean that any new flooring also needs to be at this standard, Your strata is quite entitled to specify much higher standards than the current or 2005 BCA.