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D E S I G N G U I D E
A
C
OU
S
T
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I n s u l a t i o n D e s i g n G u i d eACOUSTIC
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N2
Introduction 2
Product Range, Applications& Selection Guides 3 13
Bradford Acoustic Solutions
Party & Inter ior WallsResidential & Commercial 14
External Walls 18
Roof/Ceiling Systems 18
Floor/Ceiling Systems 23
Floors 24
Plumbing 25
Gutters & Downpipes 26
Pipes, Tanks & Vessels 27
Factories & Workshops 27
Acoustic Baffles 29
Acoustic Enclosures 30
Vibration Damping 34
Air Conditioning Systems 36
Bradford Acoustic Solutions forSpecialty Applications
Home Cinema 46
Auditor iums 47
Sports Complexes 48
Canteens/Restaurants 50Karaoke/Night Clubs 50
Shopping Centres 51
Recording Studios 52
Heavy Plant 53
OEM Application 53
Appendix A The Nature of Sound 54Sound Transmission 57Flanking Paths 59Sound Absorption 59
Reverberation 61Room Acoustics 64Industrial Acoustics 67Speech Privacy 68
Appendix B Floor/Ceiling Systems 69 70
Appendix C Product Data 71Sound Absorption Coefficients 74Static Insertion Loss/Silencers 77Air Flow Resistivity 78
Appendix D Terminology 79
CSR Bradford InsulationRegional Contact Details 80
Contents. Introduction.The Bradford Insulation Group forms part of the
Building Materials Division of CSR Limited. CSR
Bradford Insulation manufactures and markets an
extensive range of insulation products offering outstanding
thermal, acoustic and fire protection properties for use in
all types of domestic and commercial buildings.Two mineral fibre insulation types are available;
Bradford Glasswool, which is manufactured by
controlled felting of biosoluble glass wool bonded with
a thermosetting resin; and Bradford Fibertex Rockwool
which is spun from natural rock and bonded with a
thermosetting resin. Both are available in sheet or roll
form and as moulded pipe insulation.
Bradford Thermofoil and Thermotuff are a range
of aluminium foil laminates available in various grades.
All CSR Bradford Insulation products are tested to
meet stringent quality control standards incorporatingquality management systems such as AS3902/ISO9002.
ABOUT THIS GUIDE.
The purpose of this guide is to provide information on the
technical benefits obtained with the inclusion of acoustic
insulation materials in the construction of all types of buildings
as well as noise control of machinery.
The range of Bradford products and their applications
is presented along with data and worked examples to
illustrate design considerations.
This Acoustic Design Guide also outlines the basicproperties of sound, and methods for its control. It does not
set out to provide a definitive solution to every conceivable
noise problem. Rather, it aims to explain the principles
involved, so that these principles can be applied along with
common sense, to overcome common acoustic problems.
Acoustics is however a complex science, and there will
be many instances where the services of specialist acoustic
consultants or noise control engineers are indispensable.
The reader is cautioned against investing large sums of
money in noise control without first seeking advice.
This is particularly pertinent where compliance withnoise abatement orders is concerned.
TECHNICAL ASSISTANCE.
To assist designers, a free and comprehensive technical
service, as well as advice and assistance in specifying and using
Bradford products is available from CSR Bradford Insulation
offices in your region. Further technical data and product
updates are also available on the CSR Building Solutions
Website: www.csr.com.au/bradford
Information included in this Design Guide relates to
products as manufactured at the date of publication. Asthe CSR Bradford Insulation policy is one of continual
product improvement, technical details as published are
subject to change without notice.
Contents.
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N3
The Importance ofAcoustic Insulation.
The minimisation of noise has become a significant environmental issue in the modern world,whether at home, at work or on holidays.
CSR Bradford Insulation manufacturers and distributes an extensive range of insulation products
that provide excellent noise control properties, as well as the traditional thermal and fire control
benefits.
Although all fibrous insulation products can provide some acoustic benefits, CSR Bradford
Insulation has a range of products specifically designed and tested for the acoustic insulation market,
including:
ACOUSTIC INSULATIONPRODUCT
Bradford Glasswool Partition Batts
Bradford SoundScreen
Bradford ACOUSTICON
Bradford Glasswool
R1.5 ACOUSTITUFF Ductliner
Bradford Glasswool
R1.5 ULTRAPHON Ductliner
Bradford ACOUSTICLAD
Bradford Glasswool ACOUSTILAG
Bradford FIBERTEX Acoustic Baffle
Bradford Glasswool SUPERTEL
Bradford Rockwool FIBERTEX 450
APPLICATIONS
Economical insulation for internal wall sound absorption
in housing, residential apartments or commercial offices.
Various systems are available to meet building codes.
Unique rockwool insulation system to reduce room-to-
room noise transmission in houses.
Commercial and residential metal roofing insulation
specially developed to reduce rain noise.
Air conditioning duct internal lining product offering full
enclosure with excellent sound absorption properties.
High performance acoustic absorption product for
ducting, silencers and other acoustic applications.
Wall absorber combining the superior acoustic properties
of Bradford Fibertex Rockwool with a perforated metal
panel system.
Pipe insulation product combining the noise barrier
properties of loaded vinyl and the absorption benefits ofglasswool. Ideal for noisy plumbing.
Rockwool batt enclosed in white polymer film used for
which is designed to be hung from the overhead structure
to provide acoustic absorption in a room or workplace.
General purpose medium density glasswool acoustic
insulation.
General purpose premium rockwool acoustic insulation
product.
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N5
22 Ceiling
Tiled Roof
Sarking
66AcousticFloor/Ceilings
Floating Floors
77 Home Cinema
55 Plumbing
11 Metal Roofing
Bradford Insulation Application &Selection Guide for Homes.
Insulation Application Product Type Product Range/Facings
Bradford ACOUSTICON Blanket Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford Glasswool ANTICON Blanket R1.5, R2.0, R2.5 Faced Light,
Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford FIBERTEX Rockwool R1.5, R2.0, R2.5 Faced Light,
ANTICON Blanket Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford THERMOFOIL Sarking Medium, Heavy Duty,
ANTIGLARE
Bradford THERMOTUFF Sarking Medium, Extra Heavy Duty, Safety
Bradford Glasswool Gold Ceiling Batts R2.0, R2.5, R3.0, R3.5, R4.0
Bradford FIBERTEX Rockwool
Ceiling Batts R2.0, R2.5, R3.0
Bradford ACOUSTILAG 2.5 - 5.0mm
Loose Fill Bags
Bradford Glasswool Partition Batts 50, 75 and 100mm
Bradford Rockwool SoundScreen 75mm
Bradford Glasswool Gold Wall Batts R1.5, R2.0
Bradford FIBERTEX Rockwool
Wall Batts R1.5, R2.0
Bradford FIBERTEX Rockwool
Cavity Wall Granulated Loose Fill Bags
Bradford ACOUSTILAG Pipe Insulation ACOUSTILAG 20, 23 and 26
Bradford HANDITUBE Pipe Insulation Stocked by CSR Bradford Insulation
Bradford FIBERTEX Rockwool Ceiling Batts R1.5 - R2.0
Bradford Glasswool Wall/Floor Batts R1.5 - R2.0
Bradford FIBERTEX Rockwool Wall/Floor Batts R1.5 - R2.0
Bradford Rockwool SoundScreen 75mm
Bradford Glasswool QUIETEL Specialty installation system
Bradford Glasswool SUPERTEL Specialty facings available
Bradford FIBERTEX Rockwool
33Acoustic Internal
Walls
44 External Walls
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N6
77Home Cinema Wall, Floor &
Ceiling Insulation.
Acoustic Absorbing Panels
Acoustic Insulation for Homes.
11
Tiled Roof Sarking or
Metal Roof Insulation
22Ceiling
Insulation
44External Wall
Insulation
55Plumbing
Insulation
33Internal Wall
Insulation
66Acoustic Floor/Ceiling &
Floating Floor Insulation
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N7
22 Ceiling
Tiled Roof
Sarking
66AcousticFloor/Ceilings
Floating Floors
77 Home Cinema
55 Plumbing
11 Metal Roofing
Bradford Insulation Application &Selection Guide for Homes.
Insulation Application Product Type Product Range/Facings
Bradford ACOUSTICON Blanket Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford Glasswool ANTICON Blanket R1.5, R2.0, R2.5 Faced Light,
Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford FIBERTEX Rockwool R1.5, R2.0, R2.5 Faced Light,
ANTICON Blanket Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford THERMOFOIL Sarking Medium, Heavy Duty,
ANTIGLARE
Bradford THERMOTUFF Sarking Medium, Extra Heavy Duty, Safety
Bradford Glasswool Gold Ceiling Batts R2.0, R2.5, R3.0, R3.5, R4.0
Bradford FIBERTEX Rockwool
Ceiling Batts R2.0, R2.5, R3.0
Bradford ACOUSTILAG 25mm 50mm
Bradford Glasswool Partition Batts 50, 75 and 100mm
Bradford Rockwool SoundScreen 75mm
Bradford Glasswool Gold Wall Batts R1.5, R2.0
Bradford FIBERTEX Rockwool
Wall Batts R1.5, R2.0
Bradford FIBERTEX Rockwool
Cavity Wall Granulated Loose Fill Bags
Bradford ACOUSTILAG Pipe Insulation ACOUSTILAG 20, 23 and 26
ARMAFLEX Pipe Insulation Stocked by CSR Bradford Insulation
Bradford FIBERTEX Rockwool Ceiling Batts R1.5 - R2.0
Bradford Glasswool Wall/Floor Batts R1.5 - R2.0
Bradford FIBERTEX Rockwool Wall/Floor Batts R1.5 - R2.0
Bradford Rockwool SoundScreen 75mm
Bradford Glasswool QUIETEL Specialty installation system
Bradford Glasswool SUPERTEL Specialty facings available
Bradford FIBERTEX Rockwool
33Acoustic Internal
Walls
44 External Walls
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N8
Acoustic Insulation for Commercial Buildings
11Ceiling Insulation
(Suspended Grid Ceilings
& Concrete Roof/Soffit)
22Internal
Partition Wall
Insulation
33Acoustic
Absorbing
Panels
44
Plumbing
Insulation
55Plant Room Wall &
Ceiling Insulation
66Fan Silencer & Fan
Casing Insulation77Air Conditioning
Duct Insulation
(Rigid & Flexible Ducts)
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N9
Insulation Application Product Type Product Range/Facings
Bradford Glasswool ANTICON R1.5, R2.0, R2.5 Faced Light,and ACOUSTICON Blanket Medium, Heavy Duty
or Specialty THERMOFOIL
Bradford FIBERTEX Rockwool R1.5, R2.0 Faced Light,ANTICON Blanket Medium, Heavy Duty or
Specialty THERMOFOIL
Bradford Glasswool SUPERTEL 25 75mmTHERMOFOIL Facing
Bradford FIBERTEX 350 Rockwool 50 - 100mmTHERMOFOIL Facing
Bradford Glasswool Ceiling Panel Overlays Factory Applied Acoustic Facings
Bradford FIBERTEX RockwoolCeiling Panel Overlays Factory Applied Acoustic Facings
Bradford Glasswool Building Blanket R1.2, R1.5, R1.8, R2.0, R2.5
Bradford FIBERTEX
RockwoolBuilding Blanket 50, 75mm, R1.5, R2.0
Bradford Glasswool Partition Batts 50, 75, 100mm
Bradford FIBERTEX Rockwool Partition Batts 45, 70mm
Bradford Glasswool ULTRATEL Board 25-100mm, Factory AppliedFacings
Bradford FIBERTEX 450 Rockwool 25-100mm,Factory Applied Facings
Bradford ACOUSTILAG Pipe Insulation ACOUSTILAG 20, 23 and 26
ARMAFLEX Pipe Insulation Stocked by CSR Bradford Insulation
Bradford Rockwool/Glasswool ACOUSTICLAD
Bradford Glasswool FLEXITEL
, Perforated 750PSUPERTEL, ULTRATEL THERMOFOIL
Bradford FIBERTEX 350 Rockwool Perforated 750PTHERMOFOIL
Bradford Glasswool FLEXITEL Perforated 750P
Bradford Glasswool SUPERTEL THERMOFOIL
Bradford Glasswool QUIETEL ACOUSTITUFF
Bradford FIBERTEX Rockwool DUCTLINER ULTRAPHON
Bradford Glasswool SUPERTEL BMF, ULTRAPHON
Bradford Glasswool ULTRATEL 25 100mm
Bradford Glasswool QUIETEL (Quietel 13mm - 50mm)
Bradford FIBERTEX Rockwool DUCTLINERBradford FIBERTEX 450 Rockwool
Bradford Glasswool SUPERTEL Perforated 750P THERMOFOIL
Bradford Glasswool DUCTLINER ULTRAPHON,
Bradford Glasswool ULTRATEL ACOUSTITUFF facings
Bradford FIBERTEX Rockwool DUCTLINER 25 100mm, R1.5 & R0.9
Bradford Glasswool MULTITEL R1.5 & R0.9
Bradford Glasswool FLEXITEL 25 100mm
Bradford Glasswool THERMOGOLD DUCTWRAP
Bradford FIBERTEX Rockwool DUCTWRAP
Bradford Glasswool R1.0 SPECITEL R1.0. R1.5
Bradford FABRIFLEX Flexible Ducting Available ex-Singapore
Bradford ACOUSTIFLEX Flexible Ducting Available ex-Singapore
Bradford Insulation Application & SelectionGuide for Commercial Buildings.
11Concrete
Roof/Soffit
Exposed Grid
Ceiling
Concealed Grid
Ceilings
22Acoustic Internal
Partitions
77Rigid Ducting
Internal Lining
44 Plumbing Insulation
Rigid Ducting
External Wrap
Flexible Duct
55Plant RoomWall & Ceiling
Insulation
66 Fan Casings
Fan Silencers
33Acoustic
Absorbing
Panels
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N10
Acoustic Insulation for Theatre, Sports& Multi-Purpose Buildings
22Sports Centre
Roof/Ceiling Insulation
Floor Insulation
Acoustic Absorbing
Panels
33Canteen
Wall Insulation
Ceiling Insulation
Acoustic Absorbing Panels
Metal Deck Rain Noise Insulation
11
Auditorium/Theatre/Cinema
Roof/Ceiling Insulation
Wall Insulation Acoustic Absorbing
Panels
44Air Conditioning
System Insulation
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N11
Insulation Application Product Type
Walls
Bradford Glasswool Partition Batts
Bradford Rockwool Partition Batts
Acoustic Absorbers
Bradford Glasswool FLEXITEL, SUPERTEL
ULTRATEL with BMF (Black Matt Facing Tissue),
ULTRAPHON or other specialty facing.
Bradford FIBERTEX Rockwool
Bradford ACOUSTICLAD Wall/Ceiling Absorber
Roof/Ceiling
Bradford Glasswool ACOUSTICON
Bradford Glasswool Ceiling BattsBradford Rockwool Ceiling Batts
Acoustic Absorbers
Bradford ACOUSTICLAD Wall/Ceiling Absorber
Bradford FIBERTEX Rockwool
Bradford Glasswool FLEXITEL, SUPERTEL
ULTRATEL with BMF (Black Matt Facing Tissue),
ULTRAPHON or other specialty facing.
Roof/Ceiling
Bradford Glasswool ACOUSTICON
Bradford Glasswool Ceiling Batts
Bradford Rockwool Ceiling Batts
Acoustic Absorbers
Bradford FIBERTEX Rockwool
Bradford Glasswool FLEXITEL, SUPERTEL
ULTRATEL with BMF (Black Matt Facing Tissue),
ULTRAPHON or other specialty facing.
Bradford ACOUSTICLAD Wall/Ceiling Absorber
Walls
Bradford Glasswool Partition BattsBradford Rockwool Partition Batts
Roof/Ceiling
Bradford Glasswool ACOUSTICON
Bradford Glasswool Ceiling Batts
Bradford Rockwool Ceiling Batts
Refer to CSR Bradford Insulation Air Conditioning Design
Guide and Product Guide.
22Sports
Buildings
Swimming
Basketball
Gymnasium
33Canteen
Facility
11Theatre, Cinema
& Auditorium
44Air Conditioning
Systems
Bradford Insulation Application & Selection Guidefor Theatre, Sports & Multi-Purpose Buildings.
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C S R B R A D F O R D I N S U L A T I O N12
Acoustic Insulation forIndustrial Applications.
66Ceiling
Insulation
11Acoustic Baffles
(suspended)
88Acoustic Wall
Absorbers 77Metal Deck
Roof Insulation
44Acoustic
Absorbing
Screens
55Acoustic Internal
Wall Insulation
33Bradford Insulation
for OEM Applications
22AcousticEnclosures for
Plant & Machinery
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N13
33 OEM Applications
22Acoustic Enclosures
for Plant & Machinery
44Acoustic
Absorbing Screens
77Metal Deck
Roofs
88Acoustic Wall
Absorbers
66 Ceilings
11Acoustic Baffles
55Acoustic Internal
Walls
Bradford Acoustic Insulation forIndustrial Applications.
Insulation Application Product Type Product Range/Facings
Bradford FIBERTEX
Acoustic Baffle Fully enclosed in white polymer film ready to hang.
Bradford FIBERTEX Rockwool 25 100mm
Bradford Glasswool FLEXITEL Density 24 120kg/m3
Bradford Glasswool SUPERTEL
Bradford Glasswool ULTRATEL
Bradford Glasswool Appliance Grade Cut to size with specialty facings
Bradford Rockwool Appliance Grade available
Bradford Glasswool QUIETEL
Bradford Glasswool SUPERTEL 25 100mm
Bradford FIBERTEX Rockwool
Bradford Glasswool Partition Batts To fit studs
Bradford FIBERTEX Rockwool Partition Batts
Bradford Glasswool Ceiling Batts 50 150mm
Bradford Rockwool Ceiling Batts
Bradford Glasswool ACOUSTICON 75mm
Bradford Rockwool ACOUSTICON
Bradford ACOUSTICLAD 25 100mm
Bradford FIBERTEX
Rockwool Specialty facings available
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N14
Interior Walls.RESIDENTIAL PARTY &
INTERNAL WALLS.
The Building Code of Australia (BCA) Sections F5 setsout Sound Transmission Class (STC) requirements for
sound insulation of floors, walls, between units, walls
between bathrooms, laundries, kitchens, between habitable
and non-habitable rooms in multi-tenancy buildings. In
late 1999, the BCA changed its acoustic rating from STC
to Sound Reduction Index (Rw). This Acoustic Design
Guide uses the STC rating units as Australasia and Asia are
familiar with STC and it is very similar to Rw. An increase
of either one STC unit or one Rw unit approximately
equals a reduction of one decibel in noise level.
Table 1 below shows common STC values of walls
used in buildings. The expected audibility for a given
STC level is also shown, based on guidelines for ambient
sound levels
TABLE 1. STC AND AUDIBILITYTHROUGH WALLS AND FLOORS.
STC Value Audibility
30 - 35 Speech audible
40 Loud speech, still heard
45 Loud speech, just heard
50 55 Speech cannot be heard
The BCA Part F5.4 Sound Insulation Of Walls
Between Units currently states a wall must have an STC
not less than 45. It has been proposed to increase this to
STC 55 in the future as STC 45 does not provide enough
acoustic privacy. STCs 50 are standard in Europe and
USA.
Generally internal walls for residential applications in
Australia use either rendered brick or lightweight double
leaf walls using plasterboard and/or fibre cement
construction on timber studs.
To improve or increase the sound transmission loss
(STL) hence the STC of these walls, the following is
required:-
EXTRA MASS.
Sound Transmission Loss (STL) depends heavily on
the surface density of a building element (mass per square
metre of surface). For every doubling of surface density,
the sound transmission loss increases by about 5dB.
The addition of denser wall sheeting products such as
CSR Gyprock Fyrchek or Soundchek plasterboard or
CSR Fibre Cement together with Gyprock Resilient
Mounts and furring channels can reduce noise levels.
DOUBLE-LEAF WALLS.
Higher transmission losses than those expected by the
Mass Law can be obtained by using double-leaf walls
with an air cavity.
Further increases in sound transmission loss,
particularly at low frequencies can be achieved by using
wider air cavities.
When a double leaf wall is uninsulated, the air in the
cavity can act as a spring, efficiently transmitting sound
energy from one side of the wall to the other.
Significant improvement in STC is obtained by
using Bradford Rockwool or Glasswool batts in the
cavity.
Acoustic tests of walls around the world have shown
the use of glasswool batts or rockwool batts inside cavity
walls reduces resonances between the two sheets and can
significantly improve the acoustic performance by up to
10 STC. Generally the thicker and/or denser the
insulation in the cavity, the higher the STC rating
resulting in less noise transmitted to the other side of the
wall. The actual improvement in STC depends on the
type of wall construction. Insulation in the cavity will also
lessen the effect of the coincidence dip in double leaf
walls.
FLANKING NOISE.
It should be noted that actual installations, as compared
to acoustic laboratories, exhibit flanking noise through
doors, windows, ventilation ducting, air gaps at ceiling,
wall and floor intersections. In addition, poor
workmanship may degrade the acoustic performance of
partitions. For these reasons, a building element
constructed in the field will usually achieve a lower STC
ratings than when tested in the laboratory.
Maximum acoustic performance can be achieved by
eliminating penetrations in walls, caulking gaps, and
staggering electrical outlet or other necessary penetrations
through the wall. Wall cavities should be completely
filled with insulation and tightly fitted around pipes,
conduits and other outlets.
Bradford Acoustic Solutions.
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N15
LOW FREQUENCY NOISE.
Low frequency noise from sources such as fans, aircraft,
road and rail traffic, and bass from amplified music can
penetrate walls easier than high frequency noise.
Therefore higher sound transmission loss (ie. higher
STC) walls are required to ensure satisfactory acoustic
performance. As a general rule, add at least 5 STC points
to the acoustic requirement of the walls when lowfrequency noise is present.
STC data for some typical partition walls is given in
Table 2. Further STC data for internal cavity walls is
available the CSR Bradford brochure Noise Reductions
For Internal Partitions or the CSR Gyprock Fire &
Acoustic Design Guide, The Red Book.
TABLE 2. STC DATA FOR TYPICAL TIMBER FRAME PARTITION SYSTEMS.
Description STC (Rw) STC (Rw) STC (Rw)
Bradford Bradford
No Glasswool Rockwool
Insulation Wall Batts Wall Batts
STC 30 - 42
1 layer 10mm CSR Gyprock Plasterboard CD
70/75mm Timber Studs
1 layer 10mm CSR Gyprock Plasterboard CD
STC 40 - 50
2 layers 13mm CSR Gyprock Fyrchek plasterboard
70/75mm Timber Studs
1 layer 13mm CSR Gyprock Fyrchek plasterboard
STC 50 - 60
2 layers 16mm CSR Gyprock Fyrchek plasterboard
90 x 35mm Staggered Timber Studs
2 layers 16mm CSR Gyprock Fyrchek plasterboard
33 38 39(75mm Batts) (45mm Batts)
Test CSR 37/67
42SoundScreen
43 47 48
(50mm Batts) (45mm Batts)
51 58 59
(50mm Batts) (45mm Batts)
* Refer to the CSR Bradford Noise Reduction of Internal Partitions brochure or the CSR Gyprock Fire & Acoustic
Design Guide (The Red Book) which show a wide range of internal partitions and their STC ratings.
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A C O U S T I C D E S I G N G U I D E
C S R B R A D F O R D I N S U L A T I O N16
Internal plasterboard or fibre cement walls using steel
stud systems are widely used in commercial construction
and offer a wide range of sound transmission loss
performance.
The methods stated previously for improving acoustic
performance of Residential Internal Walls also apply to
the Commercial Internal Partitions.
Thinner gauge steel studs, with greater stud spacing
and minimum fixing of sheets to studs also results in a wall
which is able to flex more easily generally resulting in
slightly higher acoustic performance.
If higher STC performance is required, there are a
number of steps that can be incorporated at the time of
construction to improve acoustic performance, as detailed
in Table 3.
TABLE 3. INSULATION FOR NOISE REVERBERATION CONTROL.
Addition STC Improvement Comments
Fit insulation into studs Up to 10 STC points Thicker and/or denser insulation
such as Rockwool is beneficial.Light gauge or deeper steel studs give
higher STC performance.
Use Gyprock Fyrchek Up to 3 STC points Use of 13mm or 16mm CSR
plasterboard if installed both sides Gyprock Fyrchek improves
performance due to extra mass.
Gyprock Resilient Channel 6 8 STC points Resilient Channel isolate the
one side Gyprock Plasterboard from the stud.
Bradford Quietel one side and 4 STC points Quietel board acts as a sound
insulation to stud isolator between the Gyprock
Plasterboard and the Stud.
Staggered and double studs Up to 10 STC points Provide sound breaks between solid
studs and Gyprock. Recommended
where impact isolation is also required.
Gyprock Resilient Mounts and Up to 10 STC points Used where high level reduction of
Furring Channel airborne and impact noise is required.
COMMERCIAL INTERNALPARTITIONS.
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C S R B R A D F O R D I N S U L A T I O N17
* Refer to the CSR Bradford Insulation Noise Reduction of Internal Partitions brochure or CSR Gyprock Fire &
Acoustic Design Guide (The Red Book) which show a wide range of internal partitions and their STC ratings.
Description STC (Rw) STC (Rw) STC (Rw)
Bradford Bradford
No Glasswool Rockwool
Insulation Partition Batts Partition Batts
STC 30 - 40 1 layer 13mm Gyprock Plasterboard CD
64mm Steel Studs
1 layer 13mm Gyprock Plasterboard CD
STC 40 - 50
1 layer 16mm Gyprock Fyrchek
64mm Steel Studs
1 layer 16mm Gyprock Fyrchek
STC 50 - 60
1 layer 13mm Gyprock Fyrchek
plasterboard 64 x 0.75mm BMT Separated Steel Studs
1 layer 13mm Gyprock Fyrchek plasterboard
STC 55 - 60
1 layer 16mm Gyprock Fyrchek plasterboard
64 x 0.75 BMT Separated Steel Studs
1 layer 16mm Gyprock Fyrchek plasterboard
STC 60 - 70
2 layers 16mm Gyprock Fyrchek plasterboard
92 x 0.75mm BMT Separated Steel Studs 2 layers 16mm Gyprock Fyrchek plasterboard
TABLE 4. STC RATINGS OF SOME COMMERCIAL INTERNAL PARTITIONS*.
A sample of the STC ratings for commercial internal partitions using steel studs taken from the Tables in the CSR Bradford
Insulation Noise Reductions for Internal Partitions brochure, together with results from recent testing.
35 40 41
(50mm Batts) (45mm Batts)
Test HAS 085
39 44 45
(50mm Batts) (45mm Batts)
45 57 58
(75mm (75mm
Wall Batts) SoundScreen)
45 55 60
(80mm Batts) (75mm
SoundScreen)
55 63 64
(75mm Batts) (70mm Batts)
CSR Bradford Insulation has available a sophisticated
Acoustic Predictor computer program, developed by CSR
Gyprock
, which can predict the STC rating of manydifferent internal partitions, in addition to those shown
above and in the brochure.
Note: For walls which require high sound transmission
loss STC greater than 50, such as those used between
recording studios or cinemas, flanking paths should be
considered, as they can derate the acoustic performance ofthe partition. For cinema walls requiring a very high STC
rating, contact CSR Bradford Insulation regarding the CSR
Gyprock Cinema Wall System, or other CSR systems.
ACOUSTIC PREDICTION SYSTEM.
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External Walls.External walls of residential buildings usually consist of
brick veneer construction, or lightweight concrete
construction,
a cladding material, usually timber or fibre cement or
occasionally double brick.
For better acoustic performance, use building materialswith more mass. Clay bricks provide high surface density
(or mass per square metre) to enable high transmission
loss.
The use of CSR Gyprock Soundchek or Fyrchek
plasterboard is recommended for interior walls. For even
higher wall STC, the use of CSR Gyprock Resilient
Mounts and Furring Channels is recommended.
For brick veneer walls add the thickest possible
rockwool or glasswool batts inside wall cavities during
construction of the building.Granulated rockwool can be retro-fitted into existing
walls of a building using a special machine which blows
granulated rockwool under pressure into the wall cavities.
Wall sheeting usually has solid connections (ie screw
or nail fixed) to the timber or steel studs and transmits
noise through these solid connections. CSR Gyprock
Resilient Mounts can reduce both noise and vibration
transmission.
To improve STC performance of single timber studs,
consider the use of Rondo resilient channels or CSR
Gyprock resilient mounts with furring channels, which
can improve STC (or Rw) by 6 to 8.
Buildings with double brick walls should use vibration
isolated wall ties to reduce the amount of noise and
vibration transmitted from one wall to the other.
Note that building elements of low acousticperformance will derate the improvements made to other
building elements ie. walls and ceilings. For example,
lightweight windows and doors can reduce the overall
STC rating of the wall.
Products.
Bradford Glasswool Wall Batts
Bradford Rockwool Wall and Ceiling Batts
Roof/Ceiling Systems.Roof/ceiling systems generally consist of either steelroofing or tile roofing. These roofing systems usually
provide average to poor acoustic performance and can be
an acoustically weak link in a building facade. It should
be noted that consideration should be given to other weak
links in the building extensions such as windows and
doors.
Low frequency noise generated by aircraft, road and
rail traffic can easily penetrate commonly used building
materials including the roofing.
Tile roofs are generally used in domestic applications.
It is recommended that Bradford Rockwool or Glasswool
Ceiling Batts be used in the roof cavity to improve both
acoustic and thermal resistance. Note the higher the
thermal resistance or R-value, the thicker the batt, and
the better the acoustic absorption.
The following points indicate methods to improve the
acoustic performance of a typical tiled roof system. Tips
on how to further improve the STC rating are provided
in (brackets)
Rockwool or glasswool insulation batts on top of the
ceiling, (the thicker the insulation or the higher the
R-rating, the better the acoustic absorption)
Using a heavy THERMOFOIL sarking as a
condensation barr ier under the roof tiles, the heavier
the better the noise reduction.
Adding Bradford SOUNDLAGG loaded vinyl over
the ceiling joists, (the heavier the better).
Thicker and/or heavier plasterboard for the ceiling,
(use fire rated plasterboard and multiple layers).
Care should be taken to minimise all gaps in the roof
ceiling to maximise the acoustic performance.GyprockPlasterboard
BradfordThermofoil orThermotuffBreather
BradfordInsulationWall Batts
ExternalCladding
Timber Frame
FIG 1.
EXTERNAL WALL INSULATION.
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Figure 2 shows how to improve the acoustic
performance of a typical tiled roof system.
Note that the gaps inherent in tile roof construction
allow noise to enter the roof cavity. Hence the use of
rockwool or glasswool insulation will maximise noise
absorption in the roof space, minimising the amount of
noise entering the room/s below.
Steel roofing is used in both commercial and
residential roofing systems in Australia, New Zealand
and Asia.
Metal deck roofing systems require a layer of thermal
insulation faced with a suitable vapour barrier to be
installed directly underneath the metal decking to guard
against condensation.
Figure 3 shows the improvement in STC of a typical
domestic roof with the addition of Bradford insulation in
the roof/ceiling system.
Bradford Glasswoolor Rockwool CeilingBatts (as indicated)
Bradford Thermofoil 733Sarking over rafters
Gyprock 10mmSupa-CeilPlasterboard Ceiling
CeilingJoist
Monier ConcreteRoof Tiles
Bradford Soundlagg(6kg/m2) over joists
FIG 2. IMPROVING ACOUSTIC PERFORMANCE OF TILED ROOF SYSTEMS.
SYSTEM
Monier concrete tile roof with one
layer of Gyprock Supa-Ceil
plasterboard fixed to ceiling joists
spaced at 600mm centres.
Add Bradford R2.5 Glasswool Batts
between joists.
Replace Bradford R2.5 Glasswool
Batts with Bradford R3.0 FIBERTEX
Rockwool Building Batts between
joists, and install Bradford
THERMOFOIL 733 over rafters.
Add Bradford SOUNDLAGG
(6kg/m2) over ceiling joists.
STC/Rw
33
41
45
50
Bradford FibertexRockwool Batts or(Bradford G lasswoolCeiling Insulation inNew Zealand)
Metal Roofing
Gyprock 10mmSupa-CeilPlasterboard Ceiling
CeilingJoist
Bradford AcousticonFoil Faced Blanket
FIG 3. IMPROVING ACOUSTIC PERFORMANCE OF STEEL ROOF SYSTEMS.
SYSTEM
Metal roofing with 1 x 10mm Gyprock
Supa-Ceil plasterboard fixed to ceiling
joists spaced at 600mm centres.
Add Bradford ACOUSTICON
foilfaced building blanket over rafters under
metal roofing.
Add Bradford R2.5 FIBERTEX
Rockwool Building Batts between joists.
Replace Supa-Ceil plasterboard with 2
layers x 13mm Gyprock Plasterboard CD
fixed to metal furring channels (at
600mm max. cts) attached by Gyprock
Resilient Mounts
Metal roofing with one layer plasterboardfixed to ceiling joists spaced at 600mm
cts. plus Bradford Ceiling Insulation
between joist. (New Zealand only).
STC/Rw
34
41
45
52
39 41
TILED ROOF SYSTEMS.
STEEL ROOFING SYSTEMS.
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The STC of a roof system (commercial, industrial or
domestic) can also be improved with the addition of
heavier building materials such as:
addition of insulation between the roof sheeting and
Bradford batts above the ceiling,
thicker steel roof sheeting,
using heavier, fire rated plasterboard or multiple layers
for the ceiling,
installing a layer of Bradford SOUNDLAGG beneath
(4 kg/m2 or heavier).
RAIN NOISE REDUCTIONWITH METAL DECK ROOFING
A common problem of steel roofing is that of rain
noise, particularly in tropical climates with high levels of
rainfall. Rain falling on metal deck roofing can cause
unacceptably high noise levels in the space below the roof.
The impact causes the stiff lightweight roof sheeting to
vibrate, thus emitting noise. Damping the vibration of the
roof sheeting reduces the emitted noise.
Rockwool and glasswool blanket products have
exceptional noise absorbing properties providing effective
damping of the steel roof sheeting.
CSR Bradford Insulation in conjunction with CSR
Gyprock have constructed a rain noise testing facility to
simulate rain noise using conventional 0.42mm thick
BHP Trimdek Hi-Ten metal roof cladding. The rain
noise test rig has four nozzles spraying water at high
pressure simulate high intensity rainfall. Continuous noiselevels of 89dB(A) were created inside the test rig, this
noise level was used for controlled testing purposes.
Figure 4 shows the rain noise insertion losses achieved
by using Bradford Insulation Blankets faced with
Thermofoil 729. All tests used 0.42mm BMT BHP
Trimdek Hi-Ten steel roofing.
Bradford ACOUSTICON Glasswool Roofing
Blanket is faced with THERMOFOIL.
ACOUSTICON has been specially developed to
provide cost effective rain noise reduction of 18dB(A)
insertion loss under metal deck roofing.
ACOUSTICON has BHP approval for use under all
types of Lysaght steel roofing profiles, including Klip-Lok.
For more information refer to the Bradford
ACOUSTICON A Quiet Step Forward brochure,
available from your nearest Bradford office.
For optimum rain noise reduction under steel roofing
in commercial, industrial and residential applications,
install 75mm Bradford ACOUSTICON.
For residential applications, ensure the correct rating of
thermal insulation is achieved for roof insulation in your
region. At least R2.0 Bradford Rockwool or Glasswool
Ceiling Batts should be installed between ceiling joists in
conjunction with a Bradford ACOUSTICON.
CSR Bradford Insulation and CSR Gyprock have
conducted many tests using various foil faced roofing
insulation blankets, ceiling tiles and fixed plasterboard
ceilings. The results of these are shown in Table 5.
In tropical climates, roofing insulation is generally
installed foil face up, ie. the foil in direct contact with the
metal deck roof sheeting. This reduces the insertion loss
of the roofing blanket by 2dB. The use of Bradford
Rockwool ACOUSTICON is therefore recommended.
Rain noise tests were conducted using the same
thickness/density glasswool blanket and varying the
surface density of foil. It was found that the mass of the
foil has no effect on the rain noise insertion loss achieved
by the insulation.
ACOUSTICON and ANTICON roofing blankets
should be installed so the blanket is firmly in contact with
the steel roofing as shown in Figure 5. This has the
added benefit of damping the metal roof sheeting and
reducing rain noise.
10 11 12 13 14 15 16 17 18 19 20
Insertion Loss db(A)
50mm Glasswool blanket
50mm Bradford Rockwool
75mm Bradford ACOUSTICON Optimum
50mm Polyester Blanket
FIG 4
RAIN NOISE REDUCTION INSERTION LOSSES
FOIL FACED ROOFING BLANKETS.
BradfordAcousticon
Support Mesh(when specified)
Bradford ThermofoilVapour Barrier
Metal Deck Roofing
Purlin
FIG 5.
REDUCTION OF RAIN NOISE METAL DECK ROOF.
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TABLE 5. NOISE REDUCTION CEILING SYSTEMS.
Ceiling System Description Rain Noise
Reduction Level
dB(A)
Bradford ANTICON R1.5 Blanket hard under metal deck roof
Bradford ACOUSTICON hard under metal deck roof
Bradford FIBERTEX
Rockwool ACOUSTICON
hard under metal deck roof
Rondo Suspended Concealed Grid Ceiling System.
1 layer x 13mm Gyprock Plasterboard CD.
Bradford ANTICON R1.5 Blanket hard under metal deck roof
Rondo Suspended Exposed Grid Ceiling System.
CSR Gyprock Ecophon 20mm Lay-in Ceiling Tiles.
Bradford ANTICON R1.5 Blanket hard under the roof.
RONDO Suspended Exposed Grid Ceiling System.
CSR Gyprock CELOTEX 16mm Lay-in Ceiling Tiles.
Bradford ANTICON R1.5 Blanket hard under the roof.
RONDO Suspended Exposed Grid Ceiling System.
Gyprock 13mm Lay-in Ceiling Tiles.
Bradford ANTICON R1.5 Blanket hard under the roof.
RONDO Suspended Concealed Grid Ceiling System.
1 layer x 13mm Gyprock Plasterboard CD.
Bradford ANTICON R1.5 Blanket hard under the roof.
RONDO Suspended Concealed Grid Ceiling System.
1 layer x 13mm Gyprock Plasterboard CD.
Bradford R1.5 GOLD BATTS or R1.5 Glasswool Building Blanket laid over the ceiling.
Bradford ANTICON R1.5 Blanket hard under the roof.
RONDO Resiliently Mounted Suspended Concealed Grid Ceiling System.
2 layers x 13mm Gyprock Fyrchek Plasterboard.
Bradford R1.5 GOLD BATTS or R1.5 Glasswool Building Blanket laid over the ceiling.
15
18
19
22
25
30
34
37
45
51
Products for Metal Deck Roofing Systems.
Bradford Glasswool Acousticon 75mm. (R1.8)
Bradford 50mm Commercial Grade Anticon
. Bradford Glasswool R1.5 Anticon 55mm.
Bradford Glasswool R2.0 Anticon 75mm.
Bradford Glasswool R2.5 Anticon 95mm.
Bradford 50mm Rockwool ACOUSTICON.
CEILINGS.
Fixed plasterboard ceilings generally provide better
sound transmission loss (ie. higher STC) than lightweight
suspended ceiling tiles and even plasterboard ceiling tiles.
This is because the fixed plasterboard ceiling is bettersealed and has less gaps. Multiple layers of plasterboard
with resilient mounting and rockwool or glasswool batts
in the cavity can provide high STC rating. The larger the
Refer to the CSR Gyprock Fire & Acoustic Design Guide (The Red Book) for additional information on rain noise
reduction ceiling systems. See comments regarding: Tropical climate applications in Bradford ACOUSTICON brochure.
ceiling cavity, the better the low frequency noise
reduction.
The ceiling can be an important area of a room to
place sound absorption particularly, when the remainder
of the rooms contains hard reflective surfaces. Rooms
having no sound absorbent surfaces typically have high
reverberation times. This results in poor acoustics,
particularly if communication is required within the
room.
Generally commonly used plasterboard ceilings,
whether fixed or lay in ceiling tiles are not very effective
at absorbing sound.
Typically, sound absorptive ceilings generally consist
of:
ceiling tiles made of high density rockwool or
glasswool (typically NRC 0.70 0.95),
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perforated plasterboard or perforated metal pan ceilings
with Bradford Rockwool or Glasswool insulation
(faced with a black tissue) above (good sound
absorption NRC 0.60 0.90),
Mineral fibre ceiling tiles (average sound absorption
NRC 0.50 0.60).
Note that better low frequency acoustic absorption
results when ceiling tiles are installed with an air cavity.The larger the air cavity, the better the low frequency
acoustic absorption.
In many commercial office buildings, noises such as
conversations, telephones r inging etc can be heard from
one office to another (also known as Crosstalk). This can
cause disruption, annoyance, and decreased productivity.
Crosstalk usually occurs from sound flanking via the
ceiling.
In commercial office buildings, the walls are built up
to the underside of the lightweight suspended ceilings(usually a metal grid), not to the concrete slab above. The
lightweight ceilings tiles used generally have a low STC
rating. The void above wall and ceiling allows sound to
flank from one room to the next via the acoustically
weak ceiling tiles. Ideally, the wall should be built up to
the underside of the floor above without gaps for sound
to pass from one side to the other.
To reduce the amount of sound flanking when a wall
does not continue to the underside of the floor above, it
is recommended that Bradford Rockwool or Glasswool
Ceiling Batts be installed between the wall/ceiling and the
underside of the floor above. The more compressed the
insulation is when installed in this way, the better the
acoustic performance. refer to Figure 6.
Alternatively, to reduce flanking via the ceiling, install
Bradford Acoustilag from the underside of the concrete
slab to the ceiling below as shown in Figures 7 and 8.
Products - Ceilings.
Bradford Rockwool Ceiling Batts R1.5, R2.0, R2.5,
R3.0. Bradford Glasswool Ceiling Batts R2.0, R2.5, R3.0,
R3.5, R4.0.
Bradford Glasswool Ceiling Panel Overlays (optional
Black Matt Facing, or ULTRAPHON)
Bradford Glasswool Absorption Blanket (optional
Black Matt Facing or ULTRAPHON
Bradford Fibertex Rockwool (optional Black Matt
Facing or ULTRAPHON)
Ducting
Ducting
Poor sound privacy caused by sound flankingthrough lightweight suspended ceiling
FIG 6. IMPROVING SOUND TRANSMISSION
CONTROL THROUGH CEILING AREA WITH
BRADFORD INSULATION.
Ducting
Ducting
Improved privacy with Bradford Rockwool or
Glasswool Ceiling Batts in ceiling space over wall
BradfordRockwool orGlasswoolPartition Batts
Bradford Rockwool or GlasswoolCeiling Batts compressedbetween ceiling and slab above
CablingDucting
NOTE: Care must be taken when passing cables through
insulation material due to possible overheating. Consult
your electrician for more details.
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Floor/Ceiling NoiseControl Systems.
Multi-storey buildings with hard flooring such as
timber, parquetry or tiles etc., can efficiently transmit both
airborne and impact noise (structure borne vibration) to
the rooms below if appropriate techniques are not
incorporated at the time of construction. Installing carpetand underlay on the floor can significantly reduce the
impact noise to the room below.
Installing R2.0 or greater, Bradford Rockwool or
Glasswool batts between the floor joists will reduce
airborne noise by approximately STC 4 6.
At the time of printing this guide, The Building
Code Of Australia (BCA) Sound Insulation of Floors
Between Units stated a floor separating sole occupancy
units must have an Rw of not less than 45. (Note: Rw
45 approximately equals STC 45). Floors must alsoprovide insulation against impact generated sound.
It should be noted that STC 45 is not always adequate
in reducing airborne sound through floors and walls. For
better acoustic privacy, it is preferable to use a higher
rating of say Rw 50 or preferably Rw 55.
RETRO-FIT OF VIBRATIONISOLATED FLOOR.
To reduce impact noise transmission through
floor/ceiling systems on existing timber, concrete or
tiled floors, a floating floor can be constructed on top ofthe existing floor.
The floating floor should use a resilient damping
material. Dense Bradford Rockwool, Glasswool or rubber
materials can be used but care is needed to choose a
material with the correct stiffness for the application and
static load. The services of an acoustic consultant should
be engaged to solve floor impact noise problems and for
the design of floating floors.
Floating floors should not be mechanical fixed (nailed
or screwed) to the existing floor as this will couple the twofloors resulting in very little damping. The resilient
material should also be used between the edges of the
floating floor and the walls of the building. Skirting
boards should also be isolated or separated from the
floating floor.
Note the floor/ceiling and floor/door heights may be
affected by the use of a floating floor. Doors may also need
undercutting if a floating floor is retro-fitted. Therefore
where clearances are important, the floating floor height
should be kept to a minimum.
C-track or timberbatten fixed to soffit
Bradford Acoustilagcurtain continuous inceiling area
Suspended ceilingtiles/plasterboard
250mm minimum
100mmminimum
FIG 7. IMPROVING SOUND TRANSMISSION
CONTROL THROUGH CEILING AREA WITH
BRADFORD ACOUSTILAG CURTAIN.
75mmBradfordReinforcedAluminiumTape
50mm min.overlap
BradfordAcoustilagcurtain
FIG 8. JOINTING ABRADFORD ACOUSTILAG CURTAIN.
Cut Bradford Acoustilagcurtain to allow installationaround pipes, ducting etc.
A tight fit should bemaintained to ensureacoustic integrity
PENETRATIONS THROUGH
BRADFORD ACOUSTILAG CURTAIN.
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REDUCING NOISE TRANSMISSIONTHROUGH TIMBER
FLOOR/CEILING SYSTEMS.
1. Fit Bradford R2.0 (or greater) Floor Batts, or
Rockwool/Glasswool Ceiling Batts tightly between
ceiling joists.
2. Fix one layer of 13mm or 16mm Gyprock Fyrchek
plasterboard to furring channels.3. For better acoustic performance (to reduce airborne
noise), choose a ceiling with more mass ie. multiple
layers of Gyprock plasterboard CD or Gyprock
Fyrchek plasterboard.
4. CSR Gyprock Resilient Mounted Furring Channels
will further improve acoustic performance as well as
impact isolation.
5. To improve impact isolation of floors, use carpet and
good quality thick underlay over timber flooring.
A large range of floor/ceiling systems incorporating
alternative acoustic upgrades is detailed in Appendix B of
this publication.Refer to the CSR Gyprock Fire & Acoustic Design
Guide The Red Book for additional information on
floor/ceiling systems.
REDUCING NOISE TRANSMISSIONTHROUGH CONCRETE
FLOOR/CEILING SYSTEMS.
For concrete floor ceiling constructions, use vibration
isolated ceiling hangers or resiliently mounted furring
channels to support the plasterboard ceiling.
Products.
Bradford Floor Batts.
Bradford Glasswool R2.0, R2.5, R3.0, R3.5, R4.0
Ceiling Batts.
Bradford Rockwool R1.5, R2.0, R2.5, R3.0
Wall/Ceiling Batts.
Bradford Glasswool Quietel (for impact isolation).
Floors.Improved air-borne sound reduction and impact
isolation can be achieved by using floating floors as shown
in Figures 11, 12 and 13.
High density, resilient Bradford Rockwool or
Glasswool Quietel can break the sound and vibration
transmission paths while having sufficient compressive
strength to support the floating floor and the room
contents. Vibrational energy is absorbed in the resilient
material rather than transmitted to the building structure.
Not only does a floating floor achieve effective structure-
borne sound control, but it also reduces the air-borne
sound transmission to and from the room below.
The Bradford Fibertex Rockwool or Glasswool
Quietel board are laid flat on the floor, ensuring all joints
are tightly butted. At the edges of the rooms, the battscontinue up the walls. For the concrete floor, waterproof
film is then used to cover the batts and a concrete screed
floor of suitable thickness is poured.
Carpet and underlay
Timber flooring
Gyprock resilient mount
Use higher density Gyprock plasterboard(Soundchek or Fyrchek) and/or multiple layers
Furring channel
BradfordGlasswool or
RockwoolInsulation
Timber joists
FIG 9. TYPICAL METHODS FOR IMPROVING
ACOUSTIC PERFORMANCE OF A TIMBER
FLOOR/CEILING SYSTEM.
Carpet and underlay
Concrete slab floor
Suspended ceiling system
Gyprock resilient mount
Higher density Gyprockplasterboard (Soundchek orFyrchek) and/or multiple layers
Furring channel
Bradford Rockwool orGlasswool Insulation
FIG 10. TYPICAL METHODS FOR IMPROVING
ACOUSTIC PERFORMANCE OF A CONCRETE
FLOOR/CEILING SYSTEM.
SYSTEM
19/20mm Timber Flooring,
200 x 50 Timber Joists at 450mm
centres, 1 layer x 13mm Gyprock
plasterboard CD.
Add Bradford R2.0 GOLD BATTS
between joists.
Add Gyprock Resilient Mounts and
Furring Channels at 600mm centres
between joists and plasterboard.
Add Carpet and Underlay. Add second
layer of 13mm Gyprock plasterboard CD
STC/Rw
35
39
52
55
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VIBRATION RESISTANCE.
As Bradford Fibermesh Rockwool is stitched to
wire mesh, the blankets are especially resistant to fallout
under conditions where vibration is present.
Bradford Fibermesh is particularly suitable for
applications involving both vibration and high
temperature where standard bonded insulation materials
are less resistant to the effects of vibration.
Products.
Bradford Glasswool QUIETEL.
Bradford FIBERTEX HD Rockwool.
Bradford FIBERTEX HD (High Density) Rockwool.
Bradford FIBERMESH Rockwool.
Plumbing.Noisy pipe work is a common problem in many
buildings. These days, pipe work building trendscommonly use inexpensive, lightweight, easily to install
materials with thin wall thicknesses which are
unacceptably noisy. Offices, hotels, apartments and
domestic houses can all benefit from reduced soil and
waste pipe noise levels. Designers, hydraulic consultants,
engineers, plumbers, owners and occupants of buildings
should all take steps to insulate pipes and ducts to reduce
noise.
Water flowing through commonly used PVC soil and
waste pipes is predominantly high frequency noise. Toeffectively reduce pipe noise, lag the pipes with Bradford
Acoustilag 20, 23 or 26 pipe insulation. The 20, 23, and
26 indicate the A-weighted [dB(A)] insertion loss
achieved by lagging PVC pipes with each of the Bradford
Acoustilag product respectively. (Refer to Appendix B
for additional information).
Note, the 20, 23 and 26dB(A) insertion losses only
apply to water flowing through PVC pipes which have
been correctly lagged with Acoustilag. Using Acoustilag
for lagging other noise sources, eg., a fan casing or sheet
metal air ducts, will generally result in lower insertion
losses to those quoted, as these noise sources have more
low frequency noise energy.
To achieve the insertion losses quoted, Bradford
Acoustilag should be installed with all joins of the
lagging overlapped or butted, tightly and taped with
Bradford 493 reinforced foil tape. Minimising all the
gaps increases the acoustic performance of the lagging.
The Building Code of Australia (BCA) states that: Soil
and waste pipes are to be separated if a soil or waste
pipe, including a pipe that is embedded in or passesthrough a floor, serves or passes through more than one
sole-occupancy unit:
Timberbattens
Particleboardor timber board flooring
Structural floorAir gap at wall
BradfordFibertex Rockwoolor Glasswool Quietel
PlywoodSheeting
FIG 11 TYPICAL FLOATING FLOOR TIMBER OVER
CONCRETE.
Floorfinish
50mmConcrete
Wire mesh
Structural floor Waterproof film
BradfordFibertex Rockwoolor Glasswool Quietel
FIG 12 TYPICAL FLOATING FLOOR CONCRETE
OVER CONCRETE.
Gyprockplasterboardceiling
BradfordQuietel Board
Timberflooring
Plywoodsheeting
Plywoodsheeting
Bradford Glasswool/RockwoolCeiling Batts
FIG 13 TYPICAL FLOATING FLOOR TIMBER OVER
TIMBER JOIST CONSTRUCTION.
All equipment is then mounted on the screed floor
which is acoustically isolated from the main building
structure.
NOTE: The upper plywood layer should not be nailed
or screw fixed to the timber below. Instead, it should float
on the base floor to effectively damp vibration. The floor
should also be isolated from the walls. CSR Bradford
Insulation recommends consulting an acoustic engineer
for the design of floating floor systems.
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(a) The pipe must be separated from the rooms of any
sole-occupancy unit by construction with an STC not
less than:
(i) STC 45 if the adjacent room is a habitable room
(other than a kitchen); or
(ii) STC 30 if the adjacent room is a kitchen or any
other room.
The Bradford ACOUSTILAG Pipe Insulationbrochure provides systems using CSR Gyprock
plasterboard to achieve the STC noise criteria specified by
the BCA. The STC 50 system specified in that brochure
is intended for applications requiring better acoustic
isolation from waste pipe noise than is specified in the BCA
eg., board rooms, offices, apartments and hotels etc.
To achieve the STCs specified in Table 6, it is
imperative that the pipes be correctly lagged (no gaps to
allow noise leakage), and the plasterboard ceiling and walls
above be airtight with no gaps into the next room.It is recommended the services of an acoustic
consultant or acoustic engineer be used to achieve
specified STC ratings. Penetrations, ducting, light fittings,
gaps in ceilings etc., can degrade the acoustic rating of the
lagging and ceiling system.
To minimise annoyance from plumbing noise, it is
advisable, at the design stage, to avoid placing bathrooms
and laundries etc., adjacent to noise sensitive areas.
Methods for minimising plumbing noise include:
Select vibration isolated pipe hangers to support pipesand minimise transmission of vibration into the
building structure. These will reduce water hammer
noise when turning the water taps on or off.
Alternatively use ARMAFLEX insulation between
pipes and the building structure.
Use water supply and drain pipes that are oversized, this
may reduce line pressure and minimise flow noise.
Where possible, use cast iron waste water pipes in place
of lightweight plastic pipe to substantially reduce
plumbing noise. The heavier, stiffer walls of cast iron
pipes effectively reduce noise.
If plastic waste water pipes must be used, use Bradford
ACOUSTILAG to effectively reduce noise.
Insulate all pipes and plumbing that are chased into
brick walls.
Select quieter plumbing equipment and appliances eg.cisterns, washing machines, clothes dryers etc.
Products.
Bradford ACOUSTILAG 20, 23 or 26.
Bradford 493 reinforced foil tape.
ARMAFLEX insulation.
Quietening Box Gutters
& Downpipes.Box gutters should be insulated with BradfordFLEXITEL or SUPERTEL Glasswool (25mm thick)
faced with heavy duty foil. Insulation can be attached to
gutters using 45mm long Bradford self-adhesive fasteners
and washers at 300 mm centres. Insulation should be held
firmly against the metal surface for maximum dampening.
For better noise reduction, use Bradford ACOUSTILAG 20.
Noisy downpipes should be insulated with Bradford
Glasswool Sectional Pipe Insulation faced with Heavy
Duty Thermofoil. Alternatively a 25mm wall thicknessARMAFLEX pipe insulation or Bradford
ACOUSTILAG 20 can be fitted around downpipes.
Products.
Bradford Glasswool FLEXITEL or SUPERTEL.
Bradford ACOUSTILAG 20.
TABLE 6. ACOUSTIC INSULATION SYSTEMS FOR PLUMBING.
System STC/Rw Bradford CSR Gyprock BradfordN Rating. ACOUSTILAG Plasterboard Insulation
BAS 01 30 ACOUSTILAG 20 1 layer 10mm NilGyprock CD
BAS 02 45 ACOUSTILAG 20 2 layers 13mm CSR 75mm BradfordGyprock CD Glasswool R1.5
BAS 03 45 ACOUSTILAG 23 2 layers 10mm CSR 75mm BradfordGyprock CD Glasswool R1.5
BAS 04 50 ACOUSTILAG 23 2 layers 13mm CSR 100mm Bradford
Gyprock CD
Glasswool, R2.0BAS 05 50 ACOUSTILAG 26 2 layers 13mm CSR 75mm Bradford
Gyprock CD Glasswool R1.5
Refer to the Bradford ACOUSTILAG brochure for additional information.
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Insulation Cladding ofPipes, Tanks & Vessels.
The insertion loss achieved by cladding pipes, tanks
and vessels will depend on a number of factors such as the
frequency of the fluid in the pipe the type and mass of
the cladding material, the thickness and density of the
(rockwool or glasswool) insulation.
It should be noted that some of these cladding systems
can actually amplify the noise at lower frequencies,
particularly if insulation with a high density is used. This
generally happens as the tank now has a larger radiating
surface. Therefore it is difficult to predict the insertion loss
of cladding systems.
It should be noted that Bradford Rockwool or
Glasswool SPI (sectional pipe insulation) will reduce pipe
noise but not as effectively as Bradford ACOUSTILAG
or insulation with a mass barrier. Higher density, meansit is less resilient than Bradford ACOUSTILAG and
more efficiently transfers noise and vibration from the pipe
to the cladding/barrier. Note: Bradford ACOUSTILAG
is not recommended for high temperature applications.
Refer to the CSR Bradford Industrial Insulation
Design Guide for installation details of cladding and pipe
lagging.
Factories & EngineeringWorkshops.
The basic methods by which industrial noise may be
controlled are:
Sound absorption absorbing the noise using mineral
fibre materials which can dissipate the sound energy
as heat.
Sound insulation (enclosing) containing the noise in
one area so that it does not cause annoyance in other
areas.
Vibration damping damping vibrating surfaces toreduce air borne sound emission.
Vibration isolation preventing acoustic energy from
entering the building structure.
These processes are illustrated in Figure 14. As the
figure shows, treatment of a factory noise problem often
involves a combination of the basic processes.
REVERBERATION CONTROL.
Factories and engineering workshops usually are
reverberant spaces due to the lack of sound absorption
within the space. Areas with multiple noise sources, such
as factories, engineering workshops, bottling plants,
machine halls, plant rooms etc usually have a high level
of reverberant noise often exceeding the safe regulatory
noise level of 85dB(A).
The use of sound absorbing materials (such as
glasswool and rockwool) to reduce reflected or reverberant
sound is the most effective means of reducing overall
sound levels in enclosed areas.
CSR Bradford Insulation manufacture a range of
rockwool and glasswool products with outstanding soundabsorption properties. These products have been tested
in acoustic reverberation rooms to determine the sound
absorption coefficients presented in the technical data
section.
A range of factory-applied facings is available, the
most common being:
black fibreglass tissues (BMF), or ULTRAPHON
THERMOFOIL laminates (solid and perforated).
An extremely effective acoustic absorber for walls
and ceilings is Bradford ACOUSTICLAD a roll
formed panel, factory lined with Bradford FIBERTEX
350 Rockwool. Each panel interlocks with its neighbour
forming a structurally reinforced joint.
Bradford ACOUSTICLAD offers excellent test
results with NRC ranges from 0.9 to 1.05. Contact CSR
Bradford Insulation for a brochure or refer to Appendix
C for the Bradford ACOUSTICLAD absorption
coefficients in 1/3 octave bands.
Vibration Damping of fancasing reduces soundemission
Insulationreduces soundflow to outside
Absorbent Liningreduces sound levelwithin enclosure
Vibration IsolationMounting reducesvibration transmissionto floor
FIG 14. BASIC NOISE CONTROL METHODS.
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Bradford ACOUSTICLAD perforated metal is
available with percentages of open area ranging from
10% to 55% and in a number of finishes including:
galvanised steel,
powder coated steel,
stainless steel and
aluminium.
Fixing details for Bradford ACOUSTICLAD are
available from your nearest Bradford office.
Bradford Rockwool and Glasswool insulation is
available with a range of facings, including:
perforated metal or expanded metal.
perforated foils,
pegboard,
wire,
plastic mesh.
Any perforated sheet facing should have an open area
greater than 10% to maximise acoustic absorption.
Other common methods for acoustic wall treatment
involve:
fixing timber battens or steel furring channels or Z
sections at a spacing to suit the facing sheets. Bradford
Rockwool and Glasswool batts are cut to size if
necessary and friction fitted between the supports. The
protective facing (e.g. perforated or expanded metal,
plastic mesh, pegboard, wire etc.) is fixed to thefurring sections or battens by nails, screws, or rivets
as appropriate. Cover strips are used to improve the
appearance.
A commonly used cost effective method for fixing
insulation (generally faced with perforated foil) on walls
and ceilings uses drive pins and speed clips. These
eliminate the need for battens or furring channels. The
drive pins are fixed to the wall usually at 450mm centres.
The insulation is pushed through the pins and held onto
the pin by the speed clips of a suitable size.
Rigid facings such as perforated metal or pegboard are
unsuitable for this application method. The advice of
adhesive suppliers should be sought before using
adhesively fixed pins in lieu of drive pins.
Ceilings may be lined by the same methods as walls.
An alternative approach is to use a fully exposed metal
suspension grid which makes it a simple matter to achieve
any air gap required behind the batts
Factories contain noise which predominantly has most
energy at low frequencies which is difficult to absorb
unless very thick insulation is used. To increase the low
frequency sound absorption of perforated noise absorbers
(such as Bradford ACOUSTICLAD), introduce an air gap
behind the insulation. This can be achieved by using larger
battens or furring channels with chicken wire to retain the
batts in position, as shown in Figure 15 below. Better
acoustic absorption results when the depth of the air cavity
is at least as thick as the insulation.
Alternatively, rockwool or glasswool insulation greater
than 75mm can be used with acoustically transparent
facings mentioned above.
Acousticlad Test Sample Configuration Noise Reduction
Perforated Coefficient
% Open Area NRC Rating
15% 50mm thick Bradford FIBERTEX 350 Rockwool
(60kg/m3) Insulation with black matt facing (BMF) 1.00
between the Rockwool and Acousticlad face.
25% as above 0.95
40% as above 1.00
15% 23mm thick Mylar film between unfaced Bradford
FIBERTEX 350 Rockwool and ACOUSTICLAD 0.90
perforated aluminium.
15% 50mm thick Bradford FIBERTEX 350 Rockwool
Insulation with black matt tissue between the1.05
Rockwool and perforated aluminium. Timber spacers
supporting panels with average air gap 30mm.
TABLE 7. ACOUSTICLAD TEST RESULTS.
Notes All acoustic tests were conducted with ACOUSTICLAD perforated aluminium panels (0.7mm thick), with Bradford 50mm thickFIBERTEX 350 Rockwool (60kg/m3) insulation.
Acoustic tests were conducted in the reverberation room at the National Acoustic Laboratories, Chatswood, Sydney, Australia. See Appendix C for absorption coefficients at each 1/3 Octave band frequency.
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Products.
ACOUSTICLAD with perforated metal facing is
available in various thicknesses and open area
percentage to accommodate acoustic absorption
requirements.
The following Bradford products can also be used:
Bradford Rockwool FIBERTEX 350, 450.
Bradford Glasswool FLEXITEL, SUPERTEL,
ULTRATEL with perforated metal, expanded metal,
wire, meshes or perforated heavy duty grade foil facings.
Bradford Acoustic Baffles.Large factories or buildings may need a greater area of
acoustic absorbing insulation than just the wall area, or may
need it concentrated in a particularly noisy section of thebuilding.
Bradford Rockwool Acoustic Baffles may be suspended
in any desired pattern to achieve extra sound absorption
in a building. Refer to Figure 16 and 17.
Sound absorption coefficients of Bradford Rockwool
Acoustic Baffles are shown in Table 8.
BAFFLE INSTALLATION.
Two popular methods of installation are detailed.
Baffles may be installed at any height, and do not need
to be all in the same plane. A regular pattern such as
parallel rows or a staggered, cross-hatched pattern is most
easily installed using a suspended ceiling grid.
Determine the number of acoustic baffles to be
installed to meet the noise reduction required. The typical
number of baffles is 1 baffle per square metre of ceiling
area. Allowance should be made for lights and sprinklers.
Installation Method 1.
The baffles can be individually suspended from the
roof structure using S hooks, galvanised wire or fine
chain. In this case, suspend baffles approximately 1
metre below the ceiling level if possible.
Chicken wire Structual wall Air gap
BradfordFibertexBatts
Facingeg. perforatedmetal
Battens
FIG 15.
ABSORPTIVE LINING WITH AIR GAP TO BOOST
LOW FREQUENCY ABSORPTION (PLAN VIEW).
FIG 16.
BRADFORD ACOUSTIC BAFFLES USED TO
ABSORB SOUND FROM NOISY EQUIPMENT.
'S' Hook
Roof framing
Bradford Acoustic Bafflesin cross-hatch pattern
Suspensionwire or chain
FIG 17.
ACOUSTIC BAFFLES SUSPENDED AND ARRANGED
IN A CROSS-HATCH PATTERN.
TABLE 8. SOUND ABSORPTION COEFFICIENTS OF BRADFORD ACOUSTIC BAFFLES.
Product Density Thickness Facing Frequency (Hz)(kg/m3) (mm) 125 250 500 1000 2000 4000 5000 NRC
Bradford Acoustic Baffle 60 50 30m 0.18 0.44 0.83 1.25 1.14 0.96 0.94 0.90
plastic film
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Installation Method 2.
Inverted 50mm x 12mm aluminium U-channels are
fixed to the underside of a ceiling grid. The baffles are
then secured to the U-channel using self tapping screws.
Products.
Bradford Rockwool Acoustic Baffles.
Acoustic Enclosures.Enclosures are an effective method of reducing noise
emitted from a particular machine or noise source. They
should be constructed of solid materials such as bricks,sheet steel, timber, plasterboard etc. Enclosures reduce
noise more effectively when they are airtight, with no
gaps or openings. This is not always possible as the
machinery inside may need to be accessed by other
machines or people, or require air flow for cooling.
Enclosures built around machinery actually
concentrate the noise inside the enclosure. Therefore it
is good practice to line the inside of enclosures with
Bradford Rockwool or Glasswool to reduce reverberant
noise levels inside.A simple acoustic enclosure is shown in Figure 19. It
has three main components:
(i) an internal lining of sound absorbent rockwool or
glasswool insulation to reduce the noise level inside
the enclosure.
(ii) a heavy barrier to reduce sound transmission to the
outside.
(iii) a resilient pad of felt or rubber to isolate the enclosure
from the floor (optional).
Broadly speaking, the sound transmission loss of anenclosure improves by about 5dB for every doubling of
the surface density (mass per square metre or kg/m2).
Thus, a 2mm thick sheet steel enclosure will reduce the
noise level by about 5dB more than a 1mm sheet steel
enclosure, assuming all other conditions are equal.
Enclosures do not attenuate all frequencies of sound
equally, so the transmission loss achieved will depend on
the frequency spectrum of the noise source. High
frequency noise is more easily attenuated than low
frequency noise.
Thus, while a lightweight enclosure may provideeffective transmission loss for a high frequency noise
source, it could however be inadequate for low frequency
noise sources.
Flanking transmission paths permit sound to by-pass
the acoustic enclosure. Typical examples are air gaps,
windows, doors, service penetrations etc. To avoid severe
reductions in insulation performance, steps should be
taken to eliminate these flanking paths as far as practical.
Caulking of air gaps and penetrations, use of door seals
or even double doors, resiliently mounted double glazing,
use of flexible couplings on pipes and ducting which
penetrate the enclosure are all means of reducing flanking
transmission.
Flanking through the floor of an enclosure can limit
the transmission loss. Sound and vibration entering the
floor on the noisy side of the enclosure can be re-radiated
to some extent on the other side.
The sound insulation performance of lightweight
enclosures may be significantly improved by the use of
double-leaf construction with a core of sound absorbing
rockwool or glasswool as shown in Figure 20. The
performance will be further enhanced if the two leaves
are of different surface densities eg: one leaf may be
1.6mm steel sheet while the other is 1.2mm steel sheet.
This reduces resonant coupling between the sheets.
The sound reduction achieved depends on the surface
density of the enclosure. Heavy materials like steel sheet
greater than 1.0mm, 16mm plywood or 19mm particle
board are typically used.
As well as trapping sound, enclosures of the type
shown in Figure 19 and 20 will also trap heat. It is oftennecessary therefore to ventilate these enclosures to avoid
overheating of the enclosed machinery. Ventilation
openings must also be acoustically treated to reduce the
escape of sound through these openings. The use of
packaged attenuators, insulation lined ducts or acoustic
louvres are commonly used.
Absorptive treatment may include not only lining
the walls and ceiling of an enclosure but also the use of
discrete screens or baffles. The latter are of particular
value where it is important that the absorptive treatmentdoes not interfere with the dissipation of heat. Where heat
could cause a problem, then Bradford Rockwool Acoustic
Baffles are specially designed for suspension below existing
Bradford Acoustic Bafflesarranged in parallel pattern
Aluminiumchannel
Mainsuspensiongrid
FIG 18.
ACOUSTIC BAFFLES FIXED IN ALUMINIUM TRACK
AND ARRANGED IN A PARALLEL PATTERN.
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Heavy duty flexible pipeconnection, and resilientmounted pipe/ductwork
Main structure ofbuilding
BradfordInsulationBlanket
Minimumcavity of200mm
Existingwindow
Smalldoubleglazedviewingwindow
Two steelsoundproofdoors with alledges sealed
Resilient/floating floorsystem
BradfordInsulationBlanket incavity
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factory roofs. Their sound absorption performance is
detailed in the previous section. Baffles will not however
be as effective at reducing noise as an enclosure.
An example of an acoustic enclosure for very high
acoustic insulation is detailed in Fig 21. It shows a room
within a room. These rooms are vibration isolated from
each other.
INSTALLATION DETAILS.
Installation of the sound absorbing rockwool or
glasswool batts to the inside surfaces of the enclosure
proceeds in a similar manner to that previously described
for reverberation control.
Where double-leaf construction is employed a larger
number of variations are possible. One simple yet effective
procedure follows:
Construct a suitable frame using steel angles, channels,
or box sections to provide at least 63mm clearance
between the two leaves. (Note the wider the cavity, thebetter the low frequency sound transmission loss). Mount
this frame on a continuous thick rubber mat.
The outer steel sheeting should then be fixed to the
frame as shown in Figure 21, using rubber strips to
reduce sound transmission from the frame to the sheet.
Bradford Fibertex 450Rockwool or Ultratel
Heavy GaugeSteel Sheet
Rubber Mounting
FIG 19.
ACOUSTIC ENCLOSURE.
Bradford Fibertex 450Rockwool or Ultratel
Heavy GaugeSteel Sheet
Rubber Mounting
FIG 20.
ACOUSTIC ENCLOSURE WITH
DOUBLE-LEAF CONSTRUCTION.
FIG 21.
ACOUSTIC ENCLOSURE WITH VERY HIGH ACOUSTIC INSULATION.
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Fix 50mm thick FIBERTEX R350 to the inside of
the sheeting using weld pins and speed clips. Bend over
the ends of the pins if necessary to avoid contact with the
inner steel sheeting when installed.
The inner sheeting may now be fixed to the frame,
again as shown in Figure 21. The sound absorbing
rockwool or glasswool batts may now be fixed to the
inside of the inner sheet using weld pins, speed clips, anda suitable facing (wire, meshing, perforated foil).
Alternatively, a perforated metal (such as Bradford
ACOUSTICLAD) or expanded metal can be used, or
for an aesthetically pleasing finish.
Any gaps, openings or joins in the outer leaf of the
enclosure, should be caulked and doors should use
acoustic door seals.
Products.
Bradford Rockwool FIBERTEX 350, 450.
Bradford Glasswool FLEXITEL, SUPERTEL,
ULTRATEL.
Bradford ULTRAPHON facing.
Partial Enclosures& Screens.
It is not always practical to totally enclose a noisy
machine. However, the use of a partial enclosure or
screening will still achieve some reduction in noise levels
particularly close to the screens. The previous discussion
on total enclosures also applies to partial enclosures.
However the overall noise reduction of partial enclosures
will not be as great, due to the openings.
As far as is practical, employee work stations should
be located in the shadow zone of the screening and not
in line with the openings in the enclosure. Reflective
surfaces near openings in a partial enclosure should be
treated with rockwool or glasswool insulation to absorb
noise.
Where a particular noise source contributes
significantly to the overall noise level in a room, it may
be controlled by a partial enclosure of the type shown in
Figure 22. Much of the sound produced within the
enclosure is absorbed, thus reducing the amount of sound
radiated into the room.
Partial enclosures can be simply fabricated by
sandwiching FIBERTEX Rockwool or Glasswool Batts
between an outer sheet of plywood and an inner lining
of pegboard. Alternatively, plain hardboard, particleboard,
plasterboard, or sheet metal may be used for the outersheet, while the inner lining may be perforated or
expanded metal. The effectiveness of a partial enclosure
depends in part on the weight of the outer sheet and the
percentage of the machinery that is enclosed.
FIG 22.
A PARTIAL ENCLOSURE.
FIG 23.
TYPICAL NOISE PROBLEM WITHOUT
ACOUSTIC ENCLOSURE .
FIG 24.IMPROVED NOISE CONTROL
WITH A PARTIAL ENCLOSURE.
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The choice of which type of Bradford FIBERTEX
Rockwool or Glasswool to use should be based on the
frequency spectrum of the noise source. Select the
material with the highest sound absorption for the
dominant frequency bands of the noise source. High
frequency sound absorption will be affected by the inner
lining. Should the dominant frequency bands of the
noise source be above 1000 Hz, the inner lining should
have a perforated open area of 11% or more to ensure
optimum sound absorption.
The effect of local absorption will be limited by the
need to provide access or ventilation to the equipment
concerned. However, local absorption permits reduction
in sound levels without significantly altering the room
reverberation time.
Figures 23 and 24 show a typical application of a
partial enclosure to reduce noise reaching an operator.
Figure 23 and 24 illustrate the use of partial acoustic
enclosures in a car assembly line application.
Products.
Bradford Rockwool FIBERTEX 350, 450.
Bradford Glasswool FLEXITEL, SUPERTEL,
ULTRATEL.
Bradford ULTRAPHON or HD Perf. facings.
FIG 25.
TYPICAL NOISE PROBLEM WITHOUT ACOUSTIC ENCLOSURE.
FIG 26.
TYPICAL PARTIAL ACOUSTIC ENCLOSURE APPLICATION.
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ACOUSTIC SCREENS.
Simple acoustic screens may be fabricated as shown in
Figure 27, and these may be supported in any framing
suitable to the particular application. Screens can act in
three ways:
As local sound absorbers (i.e. a simple partial
enclosure),
As reverberation control (i.e. more absorption isintroduced to the room),
As a partial barrier (i.e. an acoustic shadow zone is
created behind the screen).
For maximum effect, acoustic screens should be
located as close as practical to the noise source or to
people affected by the noise. They should be as large as
possible, at least the height or width of the machine or
noise source. Air flow requirements should be considered.
Products.
Bradford Rockwool FIBERTEX 350, 450.
Bradford Glasswool SUPERTEL, ULTRATEL.
Bradford ULTRAPHON facing.
NOTE: Where the noise level emitted by a factory is
above acceptable community standards, it is wise to
engage the services of a noise control engineer.
Environmental noise legislation is quite complex, and
failure to comply with the relevant noise criteria may
result in severe penalties. Each situation presents its own
unique problems which must be identified and then
corrected.
Vibration Damping.Vibrating surfaces such as fan casings, pipes, and
ducting can be a major source of noise. Lagging these
surfaces will significantly reduce the noise radiated from
the sources. When treating such surfaces in this manner,
it is essential that lagging be applied over the entire
sound-radiating surface. It is also necessary to avoid
bridging connections between the radiating surface and
the outer cladding. Otherwise, the vibration will be
transmitted directly to the cladding which will itself
become a sound-radiating surface.
VIBRATION ISOLATION.
Vibration isolation involves the isolation of vibrating
machinery from the building structure. In practice this is
achieved by using flexible, resilient mountings, such as
rubber-in-shear rubber or steel springs. Where equipment
is mounted on inertia block