viracon acoustical glass

acousticalglassspecs &tech

290822 AcousGlass.qxd:260669 Viracon VSG006.qxd 2/11/09 9:52 AM

putting a damper on noisewe hear you

AIt all starts with taking

your “what if” questions and

turning them into “why not”

answers. Chances are, we‘ve

recommended a solution for a

similar job over the past 35

years. And chances are today,

we can give you a point of view

other fabricators just don’t feel

comfortable talking about. Trust,

confidence, peace of mind—

it’s what acoustical experience,

a broad selection of glazing

options and the technical

expertise to fabricate customized

solutions can do for you. After

all, the last thing we want is for

you to have to make design

changes that compromise your

vision. And your clients’. It’s

simple: when it comes to

working with you on acoustical

glass ideas, we’re good listeners.

Challenge us, you’ll see.

From imaginative aesthetics to strict environmental and energy issues to critical budget

requirements, we know how to help you figure out a way to make it all work. That’s what

being a leader is all about. Architects, designers, contractors and visionaries throughout the

world have come to rely on our proven experience to make Viracon their “go to” company

when it comes to exploring options. And getting answers. The fact is, after 35-plus years,

100,000 buildings and 500,000,000 square feet of glazing installed in some of the world’s

most remarkable buildings, you learn a thing or two about what’s the best thing to do. Today,

we perform more glass fabricating processes at a single site than any other fabricator.

Sit down, tell us your thoughts, challenge us. The sky’s the limit.

San Francisco International Airport

San Francisco, California

Architect: Skidmore, Owings & Merrill LLP

Glazing Contractor: Harmon Ltd.

Photographer: Richard Barnes

2


viraconsultingtFIELD SALES REPRESENTATIVES

We’re here to help with design assistance, budget costing, return on

investment costing, spec writing and review as well as act as a liaison

between architects and glazing contractors. We also work closely with

the glazing contractor to offer assistance with initial costs, final pricing

negotiations, product information and job site inspections. Just ask.

ACCOUNT REPRESENTATIVES & CUSTOMER SUPPORT

Call on us to help with quoting, product performance data, pricing, project

coordination, samples and mockups. All it takes is a phone call.

techelpNeed an answer—fast? Our Architectural Technical Services group, along with

our Architectural Design group, can assist you with specification and design

assistance, performance and environmental analyses, structural calculations,

energy payback, hurricane requirements and security threat levels. No problem.

3


Viracon acoustical glass

Acoustical Glass

For today’s design professional, selecting the right glass for commercial

buildings can be a challenge. Many factors must be taken into account,

such as meeting the original design concept, as well as solar, optical

and acoustical performance requirements.

While glass is inherently a poor performer when considering its sound

attenuating (sound transmission) characteristics, combinations of

various glass types and acoustical window frames can effectively

reduce sound transmissions.

Sound transmission through building walls and glass is related to the

limp/mass law. Simply stated, the heavier, more flexible the material is,

the better it will be at reducing sound transmission. Since glass is

essentially lightweight and very stiff, it tends to transmit more sound

than other building materials.

Acoustical Barriers

Sound transmission into a building may occur through many sources

other than glass or windows. Consequently, another performance

aspect to consider is the entire wall or building envelope.

While sound may be transmitted through many components of a

building wall, this transmitted sound may be absorbed in varying

degrees by other components within the wall and by the building

itself. When soundwaves strike a wall, a portion of this energy is

reflected, transmitted or absorbed by the wall.

This distribution of sound energy varies as a function of the wall

construction and its components. Porous materials within the wall,

such as fiberglass, mineral wool and foam insulation, tend to absorb

more of the sound energy. This is the result of the frictional drag of

vibrating air molecules as they attempt to pass through the fibers or

structure of the insulating materials—commonly referred to as sound

damping. Sound damping may occur with the building interior, as well

as furniture, wall and floor coverings.

Another condition that can occur in building wall construction is

sound flanking. Flanking is the transmission of sound from one side of

an acoustical barrier to the other through alternative routes—

other than the acoustical barrier. For example, with an exterior wall

there may be a number of alternative flanking paths that affect the

performance of a wall. Some of these include water and steam pipes,

HVAC ducts, electrical conduits, outlets, plumbing, drains, wall vents

and openings (holes or cracks).

Glass as a Sound Barrier

Glass is inherently a “poor performer” when considering sound

transmission characteristics. Fortunately, the glass used in building

construction provides other substantial benefits. As a result, we tend

to find ways to optimize the acoustical performance of glass for

specific applications.

With any material, the sound transmission loss is dependent on its

mass, stiffness and damping characteristics. With a single glass ply, the

4

CONTINUING EDUCATION

We also work with

professional organizations

and firms worldwide to

provide AIA registered

educational seminars. As a

registered provider with the

AIA/Continuing Education

System (AIA/CES), architects

can receive 1.5 continuing

learning units (LU’s)

with AIA/CES, including

health, safety and welfare

credits. You can schedule a

presentation by visiting our

web site at www.viracon.com

or by calling 800-533-2080.


only effective way to increase its performance is to increase the thick-

ness, because stiffness and damping cannot be changed. The sound

transmission loss (STL) for a single glass ply, measured over

18 different frequencies, varies depending on glass thickness.

Thicker glass tends to provide greater sound reduction even though

it may actually transmit more sound at specific frequencies. The critical

frequencies may show improvements to sound transmission loss while

the noncritical frequencies actually transmit more sound. This is due

to the three distinct regions in which glass reacts to sound: mass

controlled, resonance controlled and stiffness controlled.

Within the resonance and stiffness regions, greater STL may be

achieved by varying the glass thickness in multiple glass ply construction.

In the mass region, an increase in weight is required.

In addition to the behavior of the glass within these regions, various

glass thicknesses and constructions (laminated, insulating or a

combination of each) have their own specific critical frequency at

which they begin to vibrate. It is at this critical frequency where the

greatest amount of sound transmission occurs.

By evaluating the STL of various tested products, one can optimize

the glass performance by carefully selecting the product that provides

the greatest STL at the range of frequencies most critical to the

building application.

Commercial buildings use a wide variety of glass types, which may

enhance solar control and safety performance. Monolithic glass plies

will provide the lowest acoustical performance levels. Laminated glass

can provide higher acoustical performance levels than monolithic glass

due to the sound damping characteristics of the polyvinyl butyral (pvb)

interlayer used to permanently bond the glass plies together. And,

insulating glass tends to provide the highest STL potential of any glass

product due to the versatility of the product and its ability to combine

monolithic and laminated glass plies.

GLASS CONSIDERATIONS

Glass Thickness

Most glazing systems have practical limits to the thickness and weight

of the glass used. This limit is due to the constraints of the window

frame design. Glass greater than 1" (25 mm) in thickness may not be

practical in standard window framing systems. In some custom window

designs, glass thicknesses up to 1-1/4" (31.7 mm) may be more

practical. And, some thicker glass products may be accommodated

by modifying gasket designs.

Unfortunately, within these thickness limits, only so much can be

achieved when considering the acoustical performance of the glass.

For example, a 1" insulating glass unit may have an ultimate sound

transmission classification (STC) rating of approximately 35. Obtaining

a higher STC rating may be impossible, even if the glass and air-space

thickness is varied, due to the restrictive overall thickness.

Higher STC ratings can be achieved within the 1" overall thickness

by substituting laminated glass plies for monolithic glass plies.

This option has limits even with an overall thickness limit of 1-1/4"

(31.7 mm). Simply stated, STC 40 values are very difficult to achieve

even with insulating glass products limited to a maximum 1-1/4"

(31.7 mm) thickness.

Glazing Orientation

In the interest of appearance, Viracon recommends orienting the

laminate to the interior, offering more glass tint and coating options for

standard 1/4" (6 mm) exterior panes. Since the pvb is a thermoplastic,

its stiffness and damping ability changes with the temperature. In

theory, the laminated pane should be oriented to the interior for cool

climates and to the exterior in warm climates. In laboratory conditions,

Viracon has seen no significant difference in sound attenuation due to

the glazing orientation.

Asymmetrical Insulating Units

Insulating units constructed with equal panes typically exhibit a

resonant frequency during which both panes vibrate together. At this

frequency, sound transmission loss is significantly lower. To counteract

this, you can use marginally different pane thicknesses. For example,

an insulating unit with one 1/4" (6 mm) and one 5/16" (8 mm) pane

exhibits a much higher STC rating.

Airspaces

Generally, larger airspaces demonstrate better sound attenuation,

because of the acoustical separation of the glass panes. If you require

a hermetically sealed insulating unit, the maximum practical airspace

thickness is 3/4" (19 mm).

If you require a larger airspace, a double-glazed application must be

considered, such as both glass panes glazed in separate rabbets. Since

this is not a hermetically sealed unit, this application may exhibit some

condensation in cold climates.

Gas Filled Insulating Units

In theory, a higher density gas in the space between panes should

have a positive effect on acoustical performance. Comparison testing

of standard symmetrical insulating units indicates that common gases,

such as argon or sulfur hexafluoride, had virtually no increased effect

on STC ratings. While some improvement was noted at some

frequencies, resonance effects actually became more pronounced.

Suggested Specifications

You can specify Viracon products, using the MASTERSPEC® Basic

Section “Glass and Glazing” or the MASTERSPEC Supplemental

Section “Decorative Glazing” software.

MASTERSPEC is a comprehensive and unbiased master specification

system produced and distributed by the American Institute of

Architects (AIA) on a licensed user basis. For further information,

call 800-424-5080.

In addition, guideline specifications for Section 08810—Glass

and additional Viracon product information is available through

McGraw-Hill’s electronic and catalog files of Sweets.

Warranty Information

Viracon’s architectural products carry limited warranties. Contact our

Inside Sales Department for copies of our product warranties.

For more information on acoustical glass or additional literature, call

800-533-2080 (E-mail address: [email protected]).

Tabular Data

The following tables itemize the results of acoustical testing of various

monolithic, laminated, insulating and laminated insulating configurations.

Testing was performed on the glass only in standard sizes for comparison

purposes. Since glazing systems affect acoustical performance, a test

should be performed, especially in critical applications.

5


STC

Frequency in Hertz (Hz)

Glass Makeup 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000

Sound Transmission Loss (dB)

1/8" (3 mm) 19 17 18 21 23 22 24 27 28 30 30 32 34 35 36 33 26 30 30

1/4" (6 mm) 23 25 25 24 28 26 29 31 33 34 34 35 34 30 27 32 37 31 31

3/8" (10 mm) 26 27 27 30 32 31 34 35 36 35 33 30 30 35 38 41 46 48 34

1/2" (12 mm) 26 30 26 30 33 33 34 36 37 35 32 32 36 40 43 46 50 51 36

OITCestimated

25

32

33

29


Glass Makeup 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 STC


GlassPly

PVB

S/S .030".76 mm

1/8"3 mm

.015".38 mm

1/8"3 mm

.030".76 mm

GlassPly

S/S

1/8"3 mm

2.5 mm 2.5 mm

1/8"3 mm

1/8"3 mm

.045"1.14 mm

1/8"3 mm

1/8"3 mm

.060"1.52 mm

1/8"3 mm

3/16"5 mm

.015".38 mm

3/16"5 mm

3/16"5 mm

.030".76 mm

3/16"5 mm

1/4"6 mm

.060"1.52 mm

1/8"3 mm

1/4"6 mm

.015".38 mm

1/4"6 mm

1/4"6 mm

.030".76 mm

1/8"3 mm

1/4"6 mm

.030".76 mm

1/4"6 mm

1/4"6 mm

.045"1.14 mm

1/4"6 mm

1/4"6 mm

.060"1.52 mm

1/4"6 mm

1/4"6 mm

.090" SGP2.29 mm

1/4"6 mm

3/8"10 mm

.030".76 mm

1/4"6 mm

1/2"12 mm

.060"1.52 mm

1/4"6 mm

5/8" HRG-216 mm

(1/4+.050+.080+.050+1/4)

1/2"12 mm

.030".76 mm

1/4"6 mm

1/4" .100" StormGuard™ 1/4"6 mm

2

3

29 29 29 25 27 29 29 31 32 34 34 34 34 35 33 36 39 41 35

27 23 27 24 27 28 29 31 33 35 35 35 33 31 32 37 41 45 33

25 26 28 27 29 29 30 32 34 35 35 36 36 35 35 38 43 46 35

4 27 27 28 28 29 30 32 34 35 36 36 37 36 35 38 43 46 35

25 25 26 29 28 30 30 32 34 35 35 36 36 36 36 39 43 46 35

27 25 26 30 31 31 33 35 35 35 35 33 33 37 41 44 48 51 36

27 27 27 30 31 31 33 34 35 36 36 35 34 37 41 45 49 52 36

27 28 27 30 31 31 33 35 36 37 37 37 36 37 41 44 48 51 37

25 25 27 30 32 32 34 35 35 35 33 32 35 40 43 46 49 51 36

27 28 26 30 31 31 32 34 35 36 36 35 35 36 40 44 48 51 36

25 29 28 30 33 33 34 36 37 37 37 36 37 41 45 48 51 53 38

26 30 27 30 33 33 34 36 37 38 37 36 37 41 45 48 51 54 38

26 29 28 30 33 33 35 36 37 38 38 37 38 41 44 47 51 54 39

31 30 29 31 32 33 33 34 35 35 34 32 34 37 40 42 44 47 36

29 30 28 32 34 35 36 38 38 38 36 38 42 46 49 52 55 57 40

39 41 46 48 50 52 56 39

29 30 29 32 35 35 37 38 38 38 37 41 44 48 50 53 56 56 41

34 32 30 33 34 35 35 37 38 40 4040 41 41 40 42 46 49 49

1 35 33 33 34 36 36 37 36 35 34

32 31 30 31 33 34 34 34 35 36 35 35 37 41 44 47 49 51 37

31

30

31

31

31

32

33

33

32

33

34

34

34

34

1/4"6 mm

.077" Vanceva® Storm

1.95 mm1/4"6 mm

27 30 30 31 31 33 32 33 34 35 35 34 36 40 43 45 47 47 36 33

36

36

36

37

352.53 mm6 mm

OITCestimated

6

MONOLITHIC GLASS (TABLE 1)

LAMINATED GLASS (TABLE 2)

*A PVB (polyvinyl butyral) interlayer is used unless otherwise indicated. SGP is DuPont’s SentryGlas® Plus interlayer. StormGuard is a tradenameof Viracon and incorporates Solutia’s Saflex® HP interlayer. HRG-2 is fabricated with 2 plies of .050" polyurethane and .080" polycarbonate.Vanceva and Saflex are registered trademarks of Solutia. SentryGlas is a registered trademark of DuPont.

290822 AcousGlass.qxd:260669 Viracon VSG006.qxd 2/18/09 1:34 PM


Glass Makeup 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 STC


GlassPly

AirSpace

1/8"3 mm

1/4"6 mm

1/8"3 mm

3/8"9 mm

1/4"6 mm

1/2"13 mm

GlassPly

1/8"3 mm

1/8"3 mm

1/4"6 mm

1/4"6 mm

1/2"13 mm

5/16"8 mm

1/4"6 mm

1/2"13 mm

3/8"10 mm

5/16"8 mm

1/2"13 mm

5/16"8 mm

1/4"6 mm

9/16"14.5 mm

26 21 23 23 26 21 19 24 27 30 33 36 40 44 46 39 34 45 28

26 23 23 20 23 19 23 27 29 32 35 39 44 47 48 41 36 43 31

27 24 29 22 22 25 30 33 35 38 40 42 42 37 37 43 46 49 35

30 24 29 26 29 33 34 36 39 41 41 40 38 37 39 43 46 48 38

28 26 32 29 29 31 35 37 38 39 41 43 41 40 41 44 47 49 39

26 24 25 31 24 32 32 35 37 39 39 38 36 38 42 44 46 49 37

32 26 25 20 24 29 33 34 38 41 43 46 46 42 36 43 48 53 37

26

26

30

33

34

32

303/16"5 mm

OITCestimated

3/8"10 mm

3/8"10 mm

5/16"8 mm

1/2"13 mm

1/2"13 mm

3/8"10 mm

29 26 26 31 30 37 36 37 39 39 40 37 35 39 43 46 48 49 39

29 23 23 29 31 34 34 35 36 36 35 35 36 40 43 47 49 48 37

34

32

1/4"6 mm

3/4"19 mm

1/4"6 mm

1/4"6 mm

1"25 mm

1/4"6 mm

27 23 28 21 27 29 34 35 37 41 43 45 44 39 39 46 49 52 38

22 19 27 23 31 30 35 35 36 39 41 42 41 36 37 46 51 56 37

31

30

7

INSULATINGGLASS (TABLE 3)

Data based on testing ~36" x 84" glass to ASTM E413-87 in an acoustical wall. Glass size and glazing system will affect STC rating.

Glass Makeup 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 STC

GlassPly

AirSpace

3 mm1/2"

GlassPly

PVB*

1/8"3 mm

.030".76 mm

GlassPly

1/8"3 mm

1/4"6 mm

5/16"8 mm

1/2"13 mm

13 mm

5/32"4 mm

.030".76 mm

5/32"4 mm

1/4"

1/8"

6 mm1/2"

13 mm5/32"4 mm

.060"

3/16"5 mm

1/4"6 mm

1/2"13 mm

3/16"5 mm

.060"1.52 mm

1.52 mm

26 21 29 28 30 34 36 40 42 44 44 44 45 46 47 52 57 58 42

29 24 30 35 35 37 39 39 40 40 40 39 44 48 52 56 59 61 42

30 25 29 33 34 38 42 42 43 44 42 41 42 44 49 52 55 57 43

32 25 29 31 33 35 37 38 39 39 40 41 42 43 43 44 45 46 41

33

35

36

35

GlassPly

PVB*

1/8"3 mm

.030".76 mm

5/32"4 mm

.030".76 mm

1/4"6 mm

.030".76 mm

1/4"6 mm

.030".76 mm

3/16"5 mm

1/4"6 mm

3/4"19 mm

3/16"5 mm

.030".76 mm

21 23 31 35 37 40 42 42 43 42 42 42 44 48 51 55 57 59 44 331/4"6 mm

.060"1.52 mm

1/8"3 mm

1/4"6 mm

3/4"19 mm

32 26 35 35 35 40 41 42 42 43 44 44 45 47 50 56 54 45 44 371/8"3 mm

.030".76 mm1.52 mm

1/4"6 mm

.060"

OITCestimated



DOUBLE LAMINATED INSULATINGGLASS (TABLE 4)


*PVB (polyvinyl butyral) interlayer


8

INSULATING LAMINATED GLASS (TABLE 5)

*Data based on testing ~36" x 84" glass to ASTM E413-87 in an acoustical wall. Glass size and glazing system will affect STC rating.

*A PVB (polyvinyl butyral) interlayer is used unless otherwise indicated.

SGP is DuPont’s SentryGlas® Plus interlayer.

StormGuard is a tradename of Viracon and incorporates Solutia’s Saflex® HP interlayer.

HRG-2 is fabricated with 2 plies of .050" polyurethane and .080" polycarbonate.

Vanceva and Saflex are registered trademarks of Solutia.

SentryGlas is a registered trademark of DuPont.


Glass Makeup 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000


GlassPly

AirSpace

3/16"5 mm

3/8"9 mm

GlassPly

PVB*

1/8"3 mm

.030".76 mm

GlassPly

1/8"3 mm

1/8"3 mm

3/16"5 mm

1/2"13 mm

1/8"3 mm

.030".76 mm

1/8"3 mm

1/4"6 mm

1/2"13 mm

1/8"3 mm

.030".76 mm

1/8"3 mm

1/4"6 mm

1/2"13 mm

1/4"6 mm

.030".76 mm

1/8"3 mm

1/4"6 mm

1/2"13 mm

1/8"3 mm

.060"1.52 mm

3/16"5 mm

1/4"6 mm

1/2"13 mm

3/16"5 mm

.060"1.52 mm

1/4"6 mm

1/2"13 mm

1/4"6 mm

.030".76 mm

1/4"6 mm

5/16"8 mm

5/8"16 mm

3/16"5 mm

.060"1.52 mm

3/16"5 mm

3/16"5 mm

11/16"17 mm

3/8"10 mm

.030".76 mm

3/16"5 mm

1/4"6 mm

3/4"19 mm

3/16"5 mm

.060"1.52 mm

3/16"5 mm

1/4"6 mm

3/4"19 mm

1/4"6 mm

.060"1.52 mm

1/4"6 mm

3/8"10 mm

3/4"19 mm

1/4"6 mm

.060"1.52 mm

1/4"6 mm

1/4"6 mm

1/2"13 mm

1/4"6 mm

.060"1.52 mm

1/4"6 mm

1/4"6 mm

1/2"13 mm 16 mm

3/16" .060" 3/16"1/4"6 mm

5/8"16 mm 5 mm

5/8" HRG-2

1.52 mm 5 mm

3/16"5 mm

1/4"6 mm

1/2"13 mm

27 27 26 24 22 28 32 35 38 38 39 40 42 43 41 45 52 57 37

26 23 25 23 27 31 34 36 38 39 41 43 45 46 43 49 55 55 39

28 20 29 24 26 30 34 36 39 42 43 44 44 41 40 47 52 56 39

28 17 28 29 33 34 38 40 40 41 41 41 41 40 43 49 54 58 40

24 23 28 26 28 33 36 37 39 42 44 46 46 43 44 50 53 55 41

30 29 31 28 31 34 37 39 41 42 44 46 45 44 47 52 55 60 42

31 29 32 30 32 35 38 40 40 42 44 46 47 46 47 52 56 61 43

28 28 34 36 33 40 41 42 43 43 42 40 40 43 49 53 57 61 43

27 27 29 29 30 35 39 40 41 42 43 46 50 52 50 53 57 59 43

28 26 32 30 35 37 40 41 43 44 45 47 47 44 47 53 57 60 44

28 29 36 32 34 39 41 41 41 43 44 45 45 46 47 52 56 61 44

25 31 38 33 37 39 42 43 43 42 40 40 41 56 50 55 58 61 43

29 24 30 29 32 37 40 40 41 42 44 45 44 45 48 53 57 59 42

33 27 33 29 32 36 39 40 42 44 46 47 47 46 47 51 54 57 43

29 24 30 29 32 37 40 40 41 42 44 45 44 45 48 53 57 59 42

32 27 29 28 31 35 37 39 41 42 43 44 43 42 45 50 53 54 41

31

31

31

30

32

36

36

37

35

36

37

37

34

36

35

353/16"5 mm

.030".76 mm

OITCTCSestimated

1/4"6 mm

1/2"13 mm 14 mm

9/16" StormGuard™28 23 30 28 32 35 36 36 37 39 41 43 43 43 45 48 50 49 40 34

1/4"6 mm

1/2"13 mm 14 mm

9/16" SGP 29 24 32 27 32 34 35 34 36 38 40 40 41 41 42 46 48 49 39 34

1/4"6 mm

1/2"13 mm 14 mm

9/16" Vanceva® Storm 29 25 30 27 31 34 35 34 36 38 40 41 42 43 44 47 50 49 39 34

.76 mm3/16"5 mm

3/16"5 mm

1/4"6 mm

1"25 mm

.030" 24 24 31 28 33 36 37 39 39 40 41 41 41 42 43 47 49 47 40 34

1.52 mm1/4"6 mm

1/4"6 mm

3/8"10 mm

1"25 mm

.060" 24 30 33 35 40 41 44 45 45 44 44 44 43 46 50 54 57 58 46 36

3/16"5 mm

1/4"6 mm

7/16"11 mm

3/16"5 mm

.030".76 mm

31 25 30 27 29 34 36 37 39 40 42 43 42 41 44 47 51 51 40 33


Glass Makeup

GlassPl y

PVBGlassPl y

AirSpace

GlassPl y

PVB

100

1/4”6 mm

.030”.76 mm

1/4”6 mm

1”25 mm

1/8”3 mm

.030”.76 mm

211/8”3 mm

Glass

1/8”3 mm

.030”.76 mm

1/8”3 mm

1”25 mm

3/1 6” 5 mm

22

28

27

125

33

27

160

37

28

200

38

31

250

42

35

315

43

38

400

45

41

500

44

42

630

44

43

800

44

44

1000

45

45

1250

49

47

1600

53

47

2000

57

45

2500

59

50

3150

62

58

4000

63

61

5000

46

42

1/8”3 mm

.030”.76 mm

1/8”3 mm

2” 3/1 6” 5 mm

24 25 34 33 34 40 41 44 44 46 47 47 48 48 46 50 55 56 45

1/4”6 mm

.030”.76 mm

1/4”6 mm

2” 50 mm

50 mm

3/1 6” 5 mm

27 36 33 33 35 39 41 45 45 46 46 46 49 51 52 56 60 62 46

1/4”6 mm

.030”.76 mm

1/4”6 mm

2” 50 mm

3/8”9 mm

34 37 33 38 40 42 44 48 47 46 45 52 56 51 55 59 61 62 46

1/8”3 mm

.030”.76 mm

1/8”3 mm

4” 100 mm

3/1 6” 5 mm

26 36 34 37 37 43 44 48 49 51 51 50 51 50 47 51 58 60 48

1/4”6 mm

.030”.76 mm

1/4”6 mm

4” 100 mm

3/1 6” 5 mm

30 37 33 38 37 42 45 49 50 51 50 48 50 53 53 57 61 64 49

1/4”6 mm

.030”.76 mm

1/4”6 mm

4” 100 mm

1/8”3 mm

.030”.76 mm

1/8”3 mm

34 38 34 40 41 45 47 51 52 53 53 51 52 55 58 60 62 64 51

1/4”6 mm

.030”.76 mm

1/4”6 mm

4” 100 mm

3/8”9 mm

38 38 33 40 40 43 46 51 52 52 50 45 48 53 56 59 62 64 49

1/2”13 mm

.060”1

1/4”6 mm

4” 100 mm

1/8”3 mm

29 33 31 36 38 43 44 46 47 49 50 52 52 55 59 59 58 60 49

1/4”6 mm

.060”1.52 mm

1/4”6 mm

4” 100 mm

1/4”6 mm

.030”.76 mm

1/4”6 mm

31 39 35 39 41 43 46 51 52 52 49 48 50 54 59 61 63 64 50

1/2”13 mm

.060”1.52 mm

1/4”6 mm

4” 100 mm

1/4”6 mm

.030”.76 mm

1/4”6 mm

31 42 33 40 42 43 46 50 50 50 49 50 52 55 60 62 64 64 50

35

33

35

39

42

39

41

44

44

40

43

43



OITCestimated

STC

.52 mm

9

DOUBLE-GLAZEDAPPLICATIONS (TABLE 6)

1. Table 6 is provided for information only and refers to field-glazed applications. Viracon supplies only the glass components.


*PVB (polyvinyl butyral) interlayer.


Glass Makeup 100 125 160 200 250 315 400 500 650 800 1000 1250 1600 2000 2500 3150 4000 5000


GlassPly

AirSpace

GlassPly

AirSpace

GlassPly

1/4"6 mm

1/2"13 mm

1/4"6 mm

1/4"6 mm

1/4"6 mm

3/16" .030" 3/16"5 mm 1.52 mm 5 mm

25 22 29 24 25 29 34 37 40 43 46 48 47 41 41 47 52 58 39 31

1/4"6 mm

1/2"13 mm

1/2"13 mm

1/2"13 mm

26 27 33 31 33 38 39 41 41 43 44 44 44 45 46 50 52 51 43 35

OITCTCSestimated

TRIPLE / CUSTOM INSULATINGGLASS (TABLE 7)

Data based on testing of ~36" x 84" glass to ASTM E413-87 in an acoustical wall. Glass size and glazing system will affect STC rating.

The .030" component is a PVB (polyvinyl butyral) interlayer.


Sound

Sound is produced when an object vibrates. Trains, planes,

automobiles and other tools of modern society produce sounds that

can be undesirable in our work and home environments. The human

ear can perceive sound as either pleasurable or annoying, depending

on the circumstances surrounding the event.

While the roar of a jet engine may seem acceptable as you travel to a

vacation destination, it may be an extreme annoyance to office workers

located close to the airport. Consequently, glass selection for commercial

building applications becomes very important.

Understanding the relationship of sound and glass allows us to

maximize the acoustical performance of glass in building constructions.

Sound that comes from one particular source may be a combination

of sound transmitted at various frequencies. Therefore, it is imperative

to select a certain glass type that is capable of reducing sound over a

range of different frequencies.

For example, a jet engine may produce sound at very low frequencies

as it starts up, but as it attains greater power it produces sound at

higher frequencies. The glass selection to reduce sound transmission

will need to have a broader range of sound reduction potential.

Figure 1 below illustrates the distribution of typical sounds and their

peak frequencies.

Since sound is produced by an object when it vibrates, the movement

of jet engine parts causes the jet to vibrate. The engine vibration

creates a disturbance in the air, which spreads out in all directions—

much like ripples from a rock dropped in still water. When air particles

are disturbed by a vibrating source, the layer of air nearest the source

follows the back and forth motion of the source. It then causes an air

pressure disturbance.

The initial disturbance gradually spreads out to air particles further

away and at a certain speed, which is known as the speed of sound.

The speed of sound varies slightly with the temperature and humidity,

but is independent of frequency.

The chain reaction of air pressure disturbance, which is a sequence of

air pressure changes (compression and rarefraction) is called a sound

wave. The number of air pressure changes spreading out from the

vibrating source is measured in cycles per second (cps). For example,

500 ripples of air pressure from the vibration is actually 500 cps,

which is the sound frequency. The basic unit of frequency is Hertz (Hz).

Sound Intensity

Sound intensity is the amount of acoustical energy in a sound wave

and is proportional to sound pressure. The most common measure of

sound pressure is sound pressure level (SPL), which is expressed in

decibels, using a compressed or logarithmic scale.

The human ear is capable of detecting very faint and loud sounds.

Differences between sounds can be dramatic and are described as

intensity. The differences in intensity between faint sounds and loud

sounds is similar to the difference in weight of a paper airplane

and a 747 jet.

The ear is not equally sensitive at all frequencies. For example, the

sound pressure level of two different noises may be the same. One

noise may be perceived as being louder if the sound power is

concentrated in a single frequency or a range of frequencies where

the ear is more sensitive. The second noise may have a single

frequency or a range of frequencies where the ear is less sensitive.

The sensitivity of hearing is generally limited to a range of 10 Hz to

20,000 Hz; however, the human ear is most sensitive to sound within

a range of 500 Hz to 8,000 Hz. Beyond this range, our hearing

capability gradually becomes less sensitive.

To accommodate for this sensitivity, sound level meters incorporate a

filtering device. The filtering is designed to correspond to the varying

sensitivity of the human ear to sounds within the audible range of

frequencies. This is referred to as A-weighting. Sound pressure

levels, using the A-weighted meter scale, are identified as dBA.

Sound Pressure Levels

Figure 2 illustrates the correlation between sound intensity or pressure

(cps) and sound pressure level. The sound pressure level is an easy

way of classifying sound intensity. Sound pressure levels are listed in

decibels (dB). Notice that a sound pressure level of 0 dB does not

mean there is no sound (see Figure 2). Instead, it means that there

is no sound detectable by a person with normal hearing.Whenever

the sound pressure level increases 10 dB, the sound intensity increases

by a factor of ten.

Under typical conditions, an individual with normal hearing cannot

detect a change in sound pressure of 1-2 dB. A difference in sound

10

Figure 1

Bass Drum

Middle C

Ringing Telephone

Television

Male VoiceFemale Voice

Speech Intelligibility

Speech Privacy

Truck

Auto Horn

Freight Train

Jet Aircraft

Propeller Aircraft

Electric Motor

Punch Press

SOU

RCE

FREQUENCY DISTRIBUTION OF TYPICAL SOUNDS

50 100 200 500 1000 2000 5000 10000

FREQUENCY IN CYCLES PER SECOND

terms and definitions


pressure of 3 dB is barely perceptible if the change is sustained and no

time lapse occurs. A change of 5 dB is clearly detected and a change

of 10 dB is perceived as twice or half the noise level.

Sound Transmission Loss

To determine the acoustical performance of glass, it is important to

consider the application in which it will be used, as well as the

framing system that supports the glass.

For each sound frequency, the reduction in sound produced by a

sound barrier is called the sound transmission loss (STL) at that

frequency. When glass is used on an exterior wall, its STL at various

frequencies is used to determine the effectiveness of the glazing.

Viracon has tested various glass configurations to determine the

sound transmission loss over a range of 100 Hz to 5,000 Hz. These

tests help designers evaluate and select the best glass to provide

greater sound transmission loss at those frequencies where the

greatest amount of noise potential exists.

As indicated earlier, the selection of window framing systems is

important when reducing sound transmission. Window framing

systems are evaluated for thermal characteristics, as well as air and

water infiltration. Certain window framing systems may perform

better acoustically than others as a design function. One important

attribute to consider is the air tightness of the system. Window

framing systems that allow greater amounts of air infiltration also

allow greater sound transmission.

Dry glazed window systems, which use rubber gaskets as weather

seals, may not be as effective at reducing sound transmission as

systems that use wet seals (gunable sealants). The combination of wet

seals with butyl or open cell foam dramatically reduces the potential

for air infiltration; thus, flanking sound transmission.

In addition, sound pressure impinging on the window framing will

cause it to vibrate, transmitting sound to the building interior.

Consequently, the window glass performance cannot solely be relied

upon to reduce sound transmission to the building interior. The sound

transmission of the window framing will result in higher levels of

sound transmission through the glass and wall.

STC RATING

Sound Transmission Class Rating

When glass is used on the building interior, the sound transmission

classification (STC) value can be used to categorize the glass

performance. The STC rating is a single-number rating system for

interior building partitions and viewing windows.

The STC rating is derived by testing in accordance with ASTM E90,

“Laboratory Measurement of Airborne Sound Transmission of Building

Partitions”. The STC value is achieved by applying the Transmission

Loss (TL) values to the STC reference contour of ASTM E413,

“Determination of Sound Transmission Class”. The STC rating is a basis

for glass selection. Its original intent was to quantify interior building

partitions, not exterior wall components. As a result, it is not

recommended for glass selection of exterior wall applications, since

the single-number rating was achieved under a specific set of

laboratory conditions.

Laboratory measurements of sound transmission loss and subsequent

STC ratings are dependent on a number of factors present at the time

of testing. The laboratory test is an “ideal test condition” used to

minimize extraneous factors from the test results. Cautious

consideration must be given to the laboratory “test results” versus

actual job conditions.

The test frame aperture size available at most testing laboratories

may also be limited and standardized to facilitate the installation of

popular products. As a result, the standardized aperture size may be

inappropriate for all products tested nor representative of actual

building conditions.

It is not recommended to estimate STC ratings based on the

performance of tested products in comparison to “new”

configurations. This is because of the critical relationship of glass

construction and its reaction to sound at various frequencies.

Minor changes to the glass construction and air-space thickness may

increase sound transmission loss at some frequencies and decrease it

in others. Depending on where the critical frequencies exist for a

particular construction, the STC rating could actually be lower even

though the glass construction was thought to have been improved

with minor modifications.

OITC RATING

Outside-Inside Transmission Class Rating

This rating is used to classify the performance of glazing in exterior

applications. This is based on ASTM E-1332 Standard Classification for

the Determination of Outdoor-Indoor Transmission Class. While STC

rating is based on a ‘White’ noise spectrum, this standard utilizes a

source noise spectrum that combines Aircraft/Rail/Truck traffic and

is weighted more to lower frequencies.

11

COMPARISON OF SOUND INTENSITY AND SOUND PRESSURE LEVEL

Sound Intensity Sound Pressure Typical Soundsor Pressure Level in dB

1,000,000,000,000 120 Thunder Clap100,000,000,000 110 Nearby Riveter10,000,000,000 100 Boiler Factory/Subway1,000,000,000 90 Loud Street Noise/Noisy Factory100,000,000 80 Noisy Office10,000,000 70 Average Street Noise1,000,000 60 Average Radio/Average Office100,000 50 Average Conversation10,000 40 Quiet Radio/Private Office1,000 30 Average Auditorium100 20 Quiet Conversation/Whisper10 10 Soundproof Room1 0 Threshold of Audibility

Figure 2


800 Park Drive, Owatonna, MN 55060507.451.9555 800.533.2080 (Toll Free)507.444.3555 FAX (Within U.S.A.) 507.451.2178 FAX (Outside U.S.A.)E-Mail: [email protected] Internet address: http://www.viracon.com

This publication describes Viracon’s architectural acoustical glass products

to help you analyze possible design options and applications. To obtain

warranty information, contact Viracon’s Architectural Inside Sales or

Technical Services Department.

The information contained in this publication is presented in good faith.

It is believed to be accurate at the time of publication. Viracon reserves the

right to change product specifications without notice and without

incurring obligation.

Viraconsulting is a registered trademark of Viracon.

MASTERSPEC is a registered trademark of the American Institute of Architects.

© 2009 Viracon. All rights reserved.VSG-006I VRJC0209C O U N C I L

U.S

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ME M B E R


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