9.1 Overview
Current BCA Sound Transmission and Insulation Requirements
Hebel PowerWall is primarily used in buildings that have a domestic type of activity purpose. The BCA generally classifies these buildings into class 1 or 10. The acoustic performance requirements for external walls in these buildings or their building elements are not currently stated in the BCA. If a building using Hebel PowerWall was required to provide acoustic performance, then the performance level requirements for a building envelope and elements would be set by the relevant authorities (i.e. Local Councils, client specific requirements and etc).
Design Recommendations
Acoustic design is a complex science, and there will be instances where a specialist acoustic consultant is required.
For walls requiring acoustic performance CSR Hebel recommends:
1. Engaging a reputable acoustic consultant on a project-by-project basis to provide design advice and installation inspections.
2. When selecting the appropriate components for Hebel PowerWall, the designer or specifier must be aware that the laboratory Rw values are almost always higher than the field measured values. Therefore, allowances should be made for the lower expected field values during the selection of the system.
3. Separate advice from a specialist acoustic consultant should be sought to determine the effect on acoustic performance due to any changes to Hebel PowerWall, and any required modification of the installation details pertaining to the systems.
4. Increasing cavity widths, using higher density or thicker insulation or plasterboard, will generally maintain or increase the acoustic performance of Hebel PowerWall.
9.2 CSR Sound Control Systems
The CSR External Sound Control Systems guide provides solution for various external sound environments, the home can be designed so the interior noise is reduced to a selected level. The purpose of this guide is to provide solutions for the design of new residential buildings subject to certain types of external noise.
External Noise
External, or environmental noise in urban areas is pollution that can intrude into homes. It has many sources and can have a number of undesirable impacts.
Common external noise sources include:
- Road, air and rail transport.
- Industrial operations.
- Entertainment venues.
- Sporting activity.
- Pool and garden equipment.
- Neighbourhood noise such as
- television, parties.
- Barking dogs and lawn mowers.
Noise Source
Noise levels from various sources have been divided into four bands measured as LAeq (see GYP 572 August – 2005):
- Quiet suburban, 50 – 55dB(A).
- Medium suburban, 55 – 60dB(A).
- Noisy suburban, 60 – 65dB(A).
- Inner city, 65 – 70dB(A).
Interior Noise Levels
The noise levels within a home that result from external noise are measured as LAeq in the same way as the noise source. The term is a measure of the loudness of a sound, with units dB(A). The A weighting indicates that the value has been filtered to focus on the frequencies to which the ear is sensitive.
Note the noise levels experienced in a home are affected to some extent by the interior furnishings. An interior noise level of LAeq 35dB(A) for road, train, industrial and neighbourhood noise, selected from Australian Standard AS/NZS2107.
Acoustics – Recommended Design
Sound Levels And Reverberation Times For Building Interiors, is considered the upper limit for sleeping areas in houses near minor roads and within the range recommended for houses near major roads.
Note the noise level 35dB(A) is very quiet. Occupants could expect to hold a conversation without raising their voices, listen to TV at low volume, and sleep unaffected. Windows and doors must be closed to achieve the stated result.
It is possible to choose a lower level of internal noise, however, the designer should consider the ability of a system to reach the level, the higher cost to achieve lower noise levels, and the sensitivity of the occupants to noise.
Fig. 9.1 Interior Noise Level Reduction Through CSR Sound Control System
| CSR System HB1 | CSR System HB2 | |
|---|---|---|
|
• 90mm Timber or Steel Framing • 1 x 10mm Gyprock Soundchek plasterboard • Bradford SoundScreen R1.6 • Hebel PowerPanel Wall System |
• 90mm Timber or Steel Framing • 2 x 10mm Gyprock Soundchek plasterboard • Bradford SoundScreen R2.0 • Bradford EnviroSeal • Hebel PowerPanel Wall System |
|
| Acoustic Rating Rw/Rw + Ctr – wall 60/50 | Acoustic Rating Rw/Rw + Ctr – wall 63/54 |
For further information see page 16 and 17 of GYP572 August 2005 “Sound Control External Noise Systems”.
