Secondary Glazing Acoustic & Noise Questions

Question 1

What dB reduction can I expect from secondary glazing?

Secondary Glazing Installers · Accepted Answer

Secondary glazing provides 30-50dB noise reduction depending on configuration. Standard glass (4mm): 30-35dB reduction. Laminated acoustic glass (6.4mm): 40-45dB reduction. Heavy acoustic laminated (10.8mm): 45-50dB reduction. To understand these numbers: 10dB reduction sounds half as loud, so 40dB reduction is extremely significant - busy traffic becomes barely perceptible whisper.

Question 2

How do I understand decibel (dB) ratings?

Secondary Glazing Installers · Accepted Answer

Decibels measure sound intensity on a logarithmic scale. Every 10dB increase sounds twice as loud. Common references: 30dB = quiet library, 50dB = moderate rainfall, 70dB = busy traffic, 80dB = loud alarm clock, 100dB = motorbike. If your street is 70dB and secondary glazing reduces 40dB, your interior becomes 30dB - library quiet. Most people notice a 3dB difference; 10dB feels halved.

Question 3

How effective is secondary glazing for traffic noise?

Secondary Glazing Installers · Accepted Answer

Exceptionally effective. Traffic noise is predominantly 125-500Hz (low frequency), which secondary glazing handles excellently due to the air gap mass-spring effect. Our London clients on A-roads consistently report transformational results - from 'constant disturbance' to 'peaceful living'. For busy roads, we recommend 100mm+ air gaps with 6.4mm+ acoustic laminated glass for optimal low-frequency attenuation.

Question 4

Can secondary glazing reduce aircraft noise?

Secondary Glazing Installers · Accepted Answer

Yes, secondary glazing significantly reduces aircraft noise. Aircraft noise spans a wider frequency range (100Hz-4kHz) than traffic. Our acoustic configurations achieve 40-48dB reduction across this spectrum. For properties under flight paths (Heathrow, Gatwick, City Airport corridors), we recommend our premium acoustic specification with 10.8mm laminated glass and 150mm air gaps where possible.

Question 5

Is secondary glazing effective for train and railway noise?

Secondary Glazing Installers · Accepted Answer

Very effective. Railway noise includes low-frequency rumble and higher-frequency wheel squeal. Secondary glazing addresses both: the air gap attenuates low frequencies while laminated glass dampens higher frequencies. Properties near rail lines typically achieve 40-45dB reduction, making the difference between intrusive noise and background awareness. We have extensive experience with Network Rail corridor properties.

Question 6

Which glass type is best for soundproofing?

Secondary Glazing Installers · Accepted Answer

For maximum soundproofing: Acoustic laminated glass. The laminated interlayer (PVB or acoustic PVB) dampens sound vibrations. Options: 6.4mm acoustic laminated (good) - 40-42dB reduction, 8.8mm acoustic laminated (better) - 43-45dB reduction, 10.8mm acoustic laminated (best) - 45-50dB reduction. We can also combine different thicknesses either side of the air gap for broadband noise reduction.

Question 7

What's the difference between laminated and standard glass for noise?

Secondary Glazing Installers · Accepted Answer

Standard glass allows sound vibrations to pass through relatively easily. Laminated glass has a plastic interlayer (PVB) sandwiched between glass layers that absorbs and dampens sound vibrations - like a shock absorber for sound. Acoustic PVB is specifically formulated for maximum sound dampening. The result: 10-15dB additional reduction over standard glass of the same thickness.

Question 8

How does air gap size affect acoustic performance?

Secondary Glazing Installers · Accepted Answer

Air gap is crucial for low-frequency noise reduction (traffic, aircraft, bass). Physics: larger gaps improve low-frequency attenuation. Recommendations: 50mm gap: good general performance, 100mm gap: excellent for traffic/aircraft (our standard recommendation), 150mm+ gap: optimal for very low frequencies. The gap creates a 'mass-spring-mass' system where air acts as a spring between two mass layers (glass panes).

Question 9

How does secondary glazing handle low-frequency (bass) noise?

Secondary Glazing Installers · Accepted Answer

Secondary glazing excels at low-frequency noise - often better than double glazing. Low frequencies require mass and air gaps to attenuate. Secondary glazing provides: larger air gaps (50-200mm vs 16-20mm in double glazing), can use thicker glass more easily, and the decoupled system prevents structural transmission. For bass-heavy noise (traffic, nightclubs, plant rooms), we specify large gaps with heavy glass.

Question 10

What do you recommend for a very busy road?

Secondary Glazing Installers · Accepted Answer

For A-roads, high streets, or roads with constant traffic: 100-150mm air gap (maximum possible in your reveal), 6.4mm-10.8mm acoustic laminated glass, ensure perfect seals - even small gaps leak sound, consider trickle vents with acoustic baffles for ventilation. This configuration typically achieves 45-50dB reduction, transforming road-facing bedrooms into peaceful sleeping spaces.

Question 11

What specification for properties under flight paths?

Secondary Glazing Installers · Accepted Answer

For Heathrow/Gatwick/City Airport flight paths: 10.8mm acoustic laminated glass (critical for broadband aircraft noise), 150mm air gap where possible (for low-frequency engine rumble), sealed frames with acoustic-rated seals, consider acoustic vents for required ventilation. Many flight path properties qualify for the airport noise insulation scheme - we can advise on eligibility and complement any scheme improvements.

Question 12

How important are seals for acoustic performance?

Secondary Glazing Installers · Accepted Answer

Absolutely critical. Sound finds the weakest point - a 1% gap in seal coverage can reduce acoustic performance by 10dB or more. Our installations use: continuous brush seals on sliding panels, compression seals on hinged panels, perimeter seals around the frame, and quality checks for seal integrity. Poor seals are the main reason DIY installations underperform compared to professional fitting.

Question 13

Does secondary glazing stop vibration noise?

Secondary Glazing Installers · Accepted Answer

Secondary glazing significantly reduces airborne noise but has limited effect on structure-borne vibration. For heavy traffic or rail vibration: the secondary frame should not touch the original window frame (air gap prevents vibration transfer), we use isolation mounts where necessary, thicker glass provides more mass to resist vibration. For severe vibration issues, additional measures like floating floors may be needed alongside secondary glazing.

Acoustic & Noise Reduction Questions

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Acoustic & Noise Reduction Questions

1What dB reduction can I expect from secondary glazing?Decibels

2How do I understand decibel (dB) ratings?Understanding

3How effective is secondary glazing for traffic noise?Traffic

4Can secondary glazing reduce aircraft noise?Aircraft

5Is secondary glazing effective for train and railway noise?Railway

6Which glass type is best for soundproofing?Glass

7What's the difference between laminated and standard glass for noise?Glass

8How does air gap size affect acoustic performance?Technical

9How does secondary glazing handle low-frequency (bass) noise?Technical

10What do you recommend for a very busy road?Solutions

11What specification for properties under flight paths?Solutions

12How important are seals for acoustic performance?Technical

13Does secondary glazing stop vibration noise?Vibration

Explore Related Topics

Installation Questions

Results Questions

Thermal Questions

Get Peace and Quiet