Acoustics in the Home Print E-mail
Good attention to design and construction detailing is critical to making your timber framed home a quiet and peaceful refuge from externally generated noises such as voices, music, lawn mowers and traffic.

That good attention is also critical to making some areas of your home less affected by internally generated noises such as voices, music, impact noises (e.g. footsteps on the stairs) and the noises made by kitchen and laundry appliances.

The use of any single material alone will not ensure a peaceful environment as it is the use of good design and construction detail as well as effective material choice that compliment each other for a successful outcome.

Below are some cost effective ways to avoid or minimise disturbance from noises which are produced inside and outside the home.

Design and Construction Detailing

Design the layout of the home so that:
  • Noisy areas such as home theatres, laundries, stairs, kitchens and children's play areas are away from sensitive living or sleeping areas.
  • The relatively quiet areas such as bedrooms or lounge rooms are next to each other.
  • The internal doors to rooms are not directly opposite each other.
  • The waste pipes and plumbing are away from sound sensitive living and sleeping areas.
  • Built-in wardrobes are on the wall between the room and the noise area.
  • Power and antenna sockets are positioned to allow television sets to be against an external wall rather than against an internal wall.

Materials choices

An important point to consider in reducing noise disturbance is that sound finds the weakest gap. Building systems are commonly given a sound insulation rating called an "Rw value" but it doesn't matter how well an individual building element is rated for noise reduction - if there are air gaps for noise to get through this will undo all of the good work.

A door in a wall usually means that the wall is not air tight. If a wall is not air tight then it is not sound tight.

For example a standard interior hollow core door does not have a very high sound insulation value so sound can travel through and around the door, into or out of the room. To improve sound insulation, improve the seal between the door and the door frame and/or replace the hollow core door with a solid core door. By doing so, the reduction in noise transmission is often greater than would be achieved by increasing the sound insulation of the wall.

Other materials choices that can be made to reduce noise include:
  • Using carpet and underlay.
  • Using a resilient material (acoustic matting) to float the floor coverings on the structural floor where hard surface floors (tiles or decorative timber coverings) are to be used on the first floor.
  • Adding bulk insulation into cavity construction to increase noise reduction. Bulk insulation works just as well as acoustic insulation when the external surfaces of the wall or floor/ceiling are not connected.
  • Separating the two external surfaces of the wall or floor/ceiling. Refer to plasterboard manufacturers for further information on how separation can be achieved.
  • Adding an extra layer of plasterboard or using denser plasterboard to line walls or ceilings of the rooms will increase its noise reduction performance.
  • Most plasterboard manufacturers have purpose made plasterboard that can improve noise reduction. Refer to their product literature for further information.

Noise within the room

Where there are many hard surfaces within a room, noise can bounce around from the wall to the ceiling, to another wall to the floor, and so on. When sound is reflected in this way it is often reinforced. The addition of sound absorbing material will lessen the noise. Soft furnishings such as cushions, sofas, curtains, carpets and fabric wall or ceiling linings will help to absorb and reduce noise that is generated in the room. Noise entering the room needs to be addressed by design and construction detailing.

Where possible television sets, radios and the like should be against an external wall rather than against an internal wall to lessen the noise transmission (and often noise amplification) through internal walls. Speakers should not be mounted on internal walls for the same reason.

Outdoor noise

An insulated timber framed brick veneer construction is as good if not better than a double brick construction at reducing noise from outside sources. A typical external wall for a brick veneered house will contain 90 mm timber stud frame with insulation batts (R1.5) and 10mm plasterboard internal liner. This system has an Rw value = 59. Double clay brick masonry has an Rw value ≥ 50. (Rw is a measure of sound reduction with higher values being better).

However, as described above, sound finds the weakest gap into the home. For example, standard single pane windows do not provide very high sound insulation so sound from outside the home will enter the home via the window. Cost effective improvements can be made by sealing the frame perimeter and/or using thicker glass.

Other things that can be done to reduce noise from the outside entering the home include designing the layout of the home and its surrounds so that:
  • Relatively quite areas such as bedrooms or lounge rooms are away from busy roads, air conditioning units, pool pumps and neighbours' outside entertaining areas.
  • Windows and doors are not directly opposite the neighbours' windows and doors.
  • The use of hard exterior surfaces such as paving is minimised especially near relatively quite rooms. A hard exterior surface reflects sound rather than absorbs it.
  • A fence or barrier can be erected or grown between an outside noise source and a window. A barrier could be "made" of screening plants grown in the ground or in pots.
  • Water features or screening plants that rustle when the wind blows can be used where an outside noise can't be avoided. These sounds of nature are much preferred and may mask some of the outside noise.

Don't forget about the roof and ceiling. You may be using the best walls and windows but the roof and ceiling also play a part in reducing noise coming into a home. Gaps in roof tiles can increase the level of noise entering a home - the use of insulation in the ceiling will help.

Regulations

The Building Code of Australia (BCA) does not have specific requirements for noise for single family dwellings.

The Building Code of Australia (BCA) provides specific minimum construction requirements related to the reduction of transmitted noise between adjoining dwellings in multi-unit and multi-level residential construction.

Timber Floors Acoustic Treatments
(PDF, 0.1 MB)
National Timber Development Council
Multi-Residential Timber Framed Construction is an innovative and time saving design and construction method, growing in popularity throughout Australia. This link provides technical data and case study bulletins of current projects.
 
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