Do you live on a busy road, railway line, flight route or in a lively street? Then noise from outside can be quite disturbing. Regular double glazing or HR++ glazing sometimes helps, but is not automatically soundproof. For real noise reduction, you need to look at the correct glass structure, gap sealing, frame and ventilation.

The short rule: soundproof glass works especially well if the glass panels have different thicknesses, possibly combined with laminated glass or acoustic foil. But without good gap sealing and a suitable frame, the effect remains limited. In this article we explain how soundproof glass works, when you need it and what you should pay attention to when choosing glass against sound.

What is soundproof glass?

Sound-resistant glass is glass that dampens outside noise better than standard glass. It is used to reduce noise pollution in the home. Think of sound from:

  • traffic, scooters and trucks
  • trains and planes
  • catering and city noise
  • children and neighbors playing
  • industry and busy shopping streets

Soundproof glass does not completely block sound, but it can significantly reduce it. The comfort difference can be large, especially with constant noises, such as traffic.

How does soundproof glass work?

Sound consists of vibrations. These vibrations travel through air, but also through materials such as glass, window frames and walls. Regular glass blocks some of the sound, but not all of it. If glass starts to vibrate, sound still comes in.

Soundproof glass tries to reduce those vibrations by:

  • use different glass thicknesses
  • add more mass
  • use laminated glass
  • use special acoustic foil
  • cleverly assemble the glass structure
  • properly seal cracks and seams

So it's not just about "thicker glass". The structure is just as important.

Image: cross-section of a sound-resistant window in which a thin and a thick glass plate vibrates differently

Is HR++ glass automatically soundproof?

No. HR++ glass is mainly intended for heat insulation. It retains heat better, but is not automatically the best solution against noise. For example, a standard HR++ pane may consist of two panes of glass of the same thickness, such as 4-15-4. This works well for heat insulation, but is not ideal for sound.

For sound insulation, an uneven (asymmetrical) glass structure often works better, for example:

  • 4-15-6
  • 5-15-8
  • 44.2-15-6
  • laminated glass with acoustic foil

The different thicknesses make it more difficult for the glass plates to vibrate in the same way. Would you first like to know what exactly HR++ is? Then read HR++ glass: what is it?.

Why different glass thicknesses help

If two sheets of glass have the same thickness, they often respond similarly to sound vibrations. This allows some of the sound to pass through the window more easily. The glass plates vibrate differently with different glass thicknesses. This helps to dampen sound better.

Glass construction Soundproofing
4-15-4 Standard
4-15-6 Better
5-15-8 Even better
44.2-15-6 Stronger soundproofing
Acoustic laminated glass Often best choice

That is why an asymmetrical glass structure is often chosen for sound-resistant glass.

Rule of thumb: an asymmetrical glass structure with acoustic foil works best — but gaps, frame and ventilation grille ultimately determine the result.

What does laminated glass do against noise?

Laminated glass consists of two panes of glass with foil in between. This foil holds the glass together in the event of breakage, but can also help protect against noise. Special acoustic foil is often used for sound insulation, which dampens vibrations better than standard foil.

Laminated glass can therefore have several advantages:

  • better sound insulation
  • more safety
  • burglary-retardant effect
  • suitable for low windows
  • Can be combined with HR++ glass

For homes on busy roads, laminated glass with acoustic foil is often a good choice. Want to know more? Read Laminated glass: what is it?.

What is acoustic foil?

Acoustic foil is a special foil between layers of glass, designed to better dampen sound vibrations. With standard laminated glass, the foil is mainly intended for safety; With acoustic laminated glass, the foil is also aimed at noise reduction. The glass also holds together better if broken, just like normal laminated glass.

Acoustic foil is interesting for:

  • traffic noise, train traffic and air traffic
  • city noise and catering
  • bedrooms on the street side
  • apartments in busy areas

Which sounds are the most difficult to block?

Not every sound is equally easy to mute. High tones are often easier to reduce than low tones. Low tones have longer vibrations and pass through structures more easily.

Examples of difficult sounds:

  • heavy trucks and motorcycles
  • humming and bass sounds of music
  • trains and planes
  • industrial installations

Sound-resistant glass helps, but with low tones the rest of the facade also plays a major role: walls, ventilation grilles, window frames and cracks.

Soundproof glass per situation

Traffic noise

Traffic noise is one of the most common reasons for choosing sound-resistant glass. Bedrooms and living rooms on the street side can be particularly affected by cars, scooters, trucks and buses. The following are important: asymmetrical glass construction, a laminated glass plate, good gap sealing, a sound-absorbing ventilation grille, a solid frame and correct installation. Replacing just the glass often helps, but you will get the best result if the entire window is addressed.

Neighborhood noise

Noise from neighbors does not always come through the window. It can also come through walls, floors, ceilings or ventilation ducts. Sound-resistant glass especially helps when sound comes in through the facade or windows (neighbors in the garden, gallery noise or noise on the street). Therefore, first check where the sound is coming from:

  • through the window
  • through cracks
  • via ventilation
  • via wall or floor
  • via ceiling or doors

Does the sound come through the wall or floor? Then soundproof glass has little effect.

Airplane noise

Airplane noise is often difficult because it partly consists of low frequencies. However, sound-resistant glass can help, especially in combination with good window frames and crack seals. The following are important: a heavy glass structure, laminated glass, acoustic foil, well-closing windows, sound-absorbing ventilation, no cracks and sturdy window frames. In areas with a lot of air traffic, the entire facade needs to be examined carefully — just replacing glass is sometimes not enough.

The bedroom

Bedrooms are one of the most important places for soundproof glass. Sound that is acceptable during the day can be very disturbing at night. Soundproof glass in the bedroom is wise in a busy street, an entertainment area, tram or train, scooters, a flight route or loading and unloading traffic.

Pay particular attention to ventilation. A bedroom must be able to ventilate, but a standard ventilation grille can let in a lot of noise. Therefore, in case of noise pollution, it is better to choose a sound-absorbing ventilation grille.

Ventilation grilles and noise

Ventilation grilles are often the weak spot in sound insulation. You can install a good sound-resistant window, but if there is a standard grille above it, sound will still come in. Therefore, also look at the grille for sound-resistant glass. Options are:

  • a sound-absorbing ventilation grille
  • a suspense cupboard
  • mechanical ventilation with silent supply
  • a grille on a less stressed facade
  • ventilation through another room

Do you want to reduce noise and ventilate? Then take ventilation into account from the start. More about this in Ventilation grille in glass.

Gap sealing is just as important as glass

Sound easily passes through small openings. A gap of a few millimeters can greatly reduce the effect of soundproof glass. Therefore please note:

  1. Does the window close properly?
  2. Are the rubbers still good?
  3. Are there gaps around the frame?
  4. Are the sealant seams tight?
  5. Does the ventilation grille close properly?
  6. Is the rotating part straight?
  7. Are hinges and locks properly adjusted?

Soundproof glass in a poorly closing window often gives a disappointing result.

The frame also plays a role

The glass is only one part of the window. The frame also determines how much sound enters. The following are important: the material of the frame, the gap seal, the profile structure, the condition of the frame, the connection to the wall, the rubbers, the ventilation facilities and the installation quality.

Old wooden frames can perform well if they close neatly and are properly sealed. Poorly closing window frames remain a problem, even with expensive glass.

Plastic frames

Plastic frames can combine well with sound-resistant glass, but you depend on the profile. Pay attention to the maximum glass thickness, the type of glazing beads, the condition of the rubbers, the number of chambers in the profile, the closure of rotating parts and the ventilation grilles. A good plastic frame with good rubbers can perform well, but here too, cracks and grilles reduce sound insulation.

Wooden frames

Wooden frames can provide good sound insulation if they close properly. Gap sealing is especially important for old wooden frames. Check the rubber or draft profiles, the hinges and locks, the sealant seams, the glazing beads, wood rot, the connection to the wall and the rotating parts. An old wooden frame with many cracks continues to let sound through, even with good glass.

Combine soundproof glass and HR++

You don't have to choose between heat insulation and sound insulation. Sound-insulating glass can simply be designed as HR++ glass. Examples:

  • HR++ glass with uneven glass thicknesses
  • HR++ glass with a laminated inner pane
  • HR++ glass with acoustic foil
  • HR++ safety glass with sound insulation

This way you simultaneously improve thermal insulation, living comfort, sound insulation and safety. This is often the best choice when renovating. Compose your own sound-resistant insulating glass and calculate the U-value in advance. Compare the glass types in Compare insulating glass: HR++, triple and vacuum, or for maximum insulation consider triple glass.

Soundproof glass and safety

Sound-resistant glass is often combined with laminated glass. In addition to noise reduction, this also provides greater safety. This is useful for low windows, floor-to-ceiling windows, front doors, sidelights, ground floor apartments, busy streets and shop fronts.

Please note: not every sound-resistant glass is automatically suitable for every safety application. The glass structure must match the location. For the options, see safety glass.

How is sound insulation measured?

Sound insulation is often expressed in decibels (dB). The higher the noise reduction, the better the glass dampens sound. A difference of just a few decibels can already be noticeable, but the experience depends on the type of sound and the environment.

Important to understand:

  • dB values are technical
  • glass performance applies under test conditions
  • in practice, window frames and cracks also count
  • ventilation grilles can reduce the result
  • low tones are more difficult to dampen

So don't just look at the highest dB value of the glass, but at the entire situation.

Which sound-resistant glass do you need?

The best choice depends on the amount of sound and the type of sound.

Situation Possible solution
Slight noise nuisance HR++ with uneven glass thicknesses
Busy street Laminated HR++ glass
Bedroom on the street Acoustic laminated HR++ glass
Lots of traffic noise Heavier asymmetrical structure
Airplane noise Heavy construction + good gap sealing
Sound and safety Laminated soundproof glass
Sound with ventilation grille Sound-absorbing grille required

In case of heavy noise pollution, always have the entire situation assessed.

Does thicker glass always make less noise?

Not always. Thicker glass can help, but thickness alone is not enough. A window with two equally thick glass plates may perform less well than a smarter asymmetrical construction. The following are important for sound: different thicknesses, mass, foil, cavity, gap seal, frame and ventilation. A well-designed glass structure works better than simply "as thick glass as possible".

Replace existing glass with sound-insulating glass

With old double glazing

Old double glazing is often not optimal for sound. The glass panes are regularly the same thickness and the gap sealing of old window frames is often poor. Replacing it with sound-insulating HR++ glass can make a big difference. Please note: does the new glass thickness fit, are the frames still good, do rubbers need to be replaced, are the glazing beads suitable, is ventilation necessary and should safety glass be used? See also Replacing double glazing.

With single glazing

Single glazing blocks out little noise. Replacing it with HR++ glass or sound-insulating HR++ glass is therefore clearly noticeable. Pay extra attention to the rebate depth, glass thickness, frame condition, gap sealing, glazing beads, ventilation and the weight of the new glass.

Thick sound-insulating glass does not always fit in old window frames. Then vacuum glass or another thin solution may be interesting, but for sound you have to look carefully at the exact structure. Measure your windows carefully with Measuring Glass.

Common mistakes with soundproof glass

  1. Think that HR++ glass is automatically soundproof — HR++ is mainly intended for heat insulation; The glass structure counts for sound.
  2. Forgot ventilation grilles — a standard grille can let in a lot of noise.
  3. Do not tackle cracks — sound can easily pass through small openings.
  4. Choose only thicker glass — thickness helps, but asymmetry and foil are often more important.
  5. Misjudging the sound source — if sound comes through walls or floors, replacing glass will only help to a limited extent.
  6. Disregard bass notes — bass, trucks and airplanes are harder to mute.
  7. Only look at the dB value — the practice depends on the entire window and facade.

Checklist: do I need soundproof glass?

  • Do you live on a busy road?
  • Are bedrooms on the street side?
  • Do you hear a lot of scooters, trucks or buses?
  • Do you live near the railway, tram or flight route?
  • Are you bothered by catering or city noise?
  • Does the sound come clearly through the window? -Are your windows old or poorly closed?
  • Do you have standard ventilation grilles?
  • Are you already replacing single or old double glazing?
  • Do you want heat insulation and sound insulation?
  • Is safety also important?

Do you answer "yes" multiple times? Then soundproof glass is probably wise.

Conclusion

Soundproof glass works especially well when the glass structure is cleverly composed. Different glass thicknesses, laminated glass and acoustic foil dampen sound much better than standard glass. HR++ glass is therefore not automatically sound-resistant, but it can be made sound-resistant.

Don't just focus on the glass. Gap sealing, frame, mounting and ventilation grilles largely determine the end result. An expensive sound-resistant window has little effect if there are still gaps around the window or if a standard grille lets sound through. Do you want less noise from outside? Then look at the entire window construction.

Read more about HR++ glass, laminated glass and the U-value of glass, or compare directly in compare insulating glass.

Want to know which sound-insulating glass suits your situation? Compose your window with custom glass, view the range insulating glass or immediately choose a sound-absorbing ventilation grille. Are you unsure about the correct structure? Feel free to ask advice via our contact form.