STC calculator for sound insulation

Accurately calculating the size of your floor or ceiling is a crucial part of planning for the installation of sound insulation or sound absorption. Having accurate measurements allows you to optimize material usage, reduce waste, and ensure that your sound environment is improved as effectively as possible. Whether you are working to reduce noise in an office, create more comfortable acoustics in a home, or optimize the sound environment in a public space, it is important to have the right basic conditions for the installation.

With our calculation program, you can quickly and accurately calculate the surface area of your floor or ceiling and thus get a clear picture of how much sound-insulating or sound-absorbing material is needed. This simplifies the planning process and makes it easier to adapt the choice of materials and installation to your specific needs. Using a digital tool to measure large areas saves time and reduces the risk of incorrect calculations, which in turn contributes to a better end result.

When it comes to sound insulation, the aim is to block sound from passing through ceilings and floors, while sound absorption focuses on reducing reverberation and reflections within the room. By using the calculator, you can determine which solution is most suitable for your specific project, thereby ensuring that you create a sound environment that is both functional and pleasant.

Using the right amount of material is crucial to achieving the desired result. Too little material can lead to insufficient sound control, while too much can be an unnecessary expense. By using our calculation program, you can customize your sound insulation or sound absorption project with precision and ensure that you get maximum results with the least possible resources. The tool is designed for both professional installers and private individuals who want to improve their sound environment in a simple and effective way.

What is an STC calculator?

We are pleased to present our free STC calculator, a tool that makes it easy for you to understand and choose the right sound insulation material for your project.

Our STC calculator is an innovative tool that helps you calculate the sound insulation of different materials. STC, or Sound Transmission Class, is a measure used to indicate how well a building element reduces sound. By using our calculator, you can easily see how different materials perform in terms of blocking sound in both STC values and decibels.

What does an STC value mean?

The STC value describes how effectively a structure can block sound transmission. The higher the STC value, the better the sound insulation. However, exact STC values can vary depending on several factors, including the quality of the installation and the possible use of supplementary sound-insulating materials.

STC value and sound transmission

STC 25-30
Normal speech can be easily heard and understood through the wall.

STC 30-35
Speech is audible and understandable, but somewhat muffled.

STC 35-40
Speech can be heard but is not always clearly understandable. Louder sounds such as shouting or music are still clearly audible.

STC 40-45
Speech sounds like mumbling and is difficult to understand. Louder sounds are muffled but still audible.

STC 45-50
Speech is noticeably muffled and not understandable without effort. Music and other loud sounds are faintly audible.

STC 50-55
Speech is very faint or inaudible. Music and other loud sounds are significantly muffled and can only be heard at high volume.

STC 55-60
Almost all sounds are inaudible; only very loud sounds may be faintly audible.

STC 60-65
Almost all types of sound, including loud music and shouting, are inaudible. Used in sound-sensitive environments such as recording studios.

STC 70
Complete sound insulation where all types of sound are completely inaudible through the wall.

These higher STC values are difficult to achieve and require advanced construction techniques and materials, but are necessary in environments where maximum sound insulation is critical, such as recording studios, laboratories, and specially designed soundproofed spaces.

How can you achieve a higher STC rating?

Effectively reducing sound transmission and achieving a higher STC rating requires a combination of the right material selection and installation methods. Aiming for STC 50 or higher means that sounds, such as speech and background noise, are greatly attenuated and in some cases become completely inaudible. To achieve this, it is important to work with several soundproofing measures and to ensure that the design is optimized to reduce both airborne and structure-borne sound.

Important factors for improving the STC value

Use of sound-insulating wall materials
To reduce sound transmission, it is crucial to choose materials with high density and soundproofing properties. Dense materials, such as plasterboard combined with soundproofing rock wool, help to absorb and block sound waves. A multi-layer construction with at least two layers of plasterboard on each side of the wall can further improve sound reduction.

Double wall construction with air gap
One of the most effective methods for increasing the STC value is to build double wall constructions where two separate walls stand with an air gap between them. The depth of the air gap plays an important role in sound reduction – generally, a depth of at least 50-100 mm is recommended to achieve a significant improvement. It is crucial that the new construction does not have direct contact with the old wall, as sound can travel through solid materials. To further prevent vibration transmission between the two walls, vibration-damping materials should be used.

Vibration-damping materials to minimize structure-borne sound
To prevent sound vibrations from being transmitted from one structure to another, it is important to use vibration-damping materials such as SilentDirect Seal or SilentDirect Neo. These products act as elastic sound barriers between the structures and prevent sound waves from propagating through solid materials.

SilentDirect Seal is used effectively in connections between floors, walls, and ceilings to create a flexible joint that reduces structure-borne sound. SilentDirect Neo is another solution that can be applied between wall elements to reduce contact surfaces and thus reduce sound transmission.

Use of acoustic seals to eliminate sound leakage
Even small gaps and cracks can drastically impair a structure's sound insulation. To optimize the STC value, all openings around doors, windows, and penetrations should be sealed with acoustic seals and sound-insulating joint compound. The seals prevent sound from leaking through the structure and ensure that the entire sound barrier functions optimally.

Sound-absorbing materials to reduce reverberation and reflections
In addition to sound insulation, sound absorption is an important factor in creating a comfortable sound environment. By combining acoustic panels, sound-absorbing carpets, and other damping materials inside the room, sound reflections can be minimized, creating a more controlled acoustic environment.

How to achieve higher sound insulation (STC value)

By combining dense wall materials, a double wall construction with an air gap, vibration-damping materials, and acoustic seals, you can significantly improve sound insulation and achieve an STC value above 50. For best results, the construction should also be supplemented with sound-absorbing materials to reduce reverberation and improve overall acoustic comfort.

Creating a well-insulated sound environment is about more than just the choice of materials – it is a comprehensive solution where the right construction techniques, installation methods, and acoustic adjustments together create optimal sound insulation.

STC calculator

Why is it important that new surfaces do not touch existing surfaces?

When building a new interior wall or soundproofing an existing wall, it is crucial that the new construction does not come into direct contact with the old surface. This is due to several acoustic and structural factors that directly affect the effectiveness of sound insulation. By ensuring that the two surfaces are separated, sound transmission via both airborne and structure-borne sound propagation can be minimized, creating a significantly better sound environment.

Reduction of sound transmission

If the new wall is in direct contact with the existing surface, sound vibrations can easily be transmitted through the structure. This means that sound from one side of the wall is transmitted to the other side through direct vibrations, rendering the sound insulation ineffective.

One of the most effective methods of breaking this transmission is decoupling, i.e. disconnecting the new wall from the old one. Creating an air gap or using specially adapted mounting brackets reduces the impact of sound vibrations, resulting in significantly improved sound reduction.

Air gaps act as a buffer zone that absorbs sound vibrations before they can propagate further into the structure. The larger the air gap, the more effective the sound insulation. In general, an air gap of at least 50-100 mm is recommended to achieve a noticeable difference in sound reduction.

Improved acoustic damping

When a wall structure is decoupled from existing surfaces, the sound is forced to pass through several layers of material and air gaps, causing the sound waves to lose more energy before reaching the other side.

Another important aspect is the choice of sound-insulating materials. Using SilentDirect Seal or SilentDirect Neo as vibration-damping layers in connections between structures further reduces sound transmission. These materials act as elastic breaks that absorb vibrations and stop sound from propagating through solid materials.

In addition to using vibration-damping materials, it is also important to seal all connection points with acoustic joint compound. Even small gaps can drastically impair sound insulation, and sealing is therefore a critical factor in maintaining high sound reduction.

Vibration damping and STC improvement

Preventing new surfaces from touching existing surfaces can have a significant impact on the STC (Sound Transmission Class) value, which measures how well a structure reduces sound.

When a structure is decoupled and vibration dampened, the STC value can be improved by between 8 and 15 STC points, depending on the design of the structure and the materials used.

Example of STC improvement through decoupling

- A wall with an STC of 40 can be increased to an STC of 48–55 through proper decoupling and insulation methods, which is a noticeable improvement where speech and other sounds become significantly less audible.

- For professional soundproofing solutions, such as recording studios and home theaters, a well-executed decoupled design can raise the STC rating to 60+, providing an almost completely soundproof environment.

This improvement is due to the fact that sound vibrations cannot be transmitted through a single, continuous structure. Instead, the sound is dispersed and gradually dampened, significantly reducing sound transmission to the other side of the wall.

Ensuring that new surfaces do not touch existing surfaces is crucial to reducing sound transmission through both airborne and structure-borne sound propagation. By using a decoupled construction with an air gap, vibration-damping materials such as SilentDirect Seal or SilentDirect Neo, and acoustic seals, sound vibrations can be effectively broken.

This method can improve the STC value by up to 15 points, creating a quieter and more comfortable environment. For best results, the design should always be tailored to the specific needs and purpose of the room, whether it is a home, workplace, or professional sound studio.

Did you know that..

A room can have a high sound insulation rating but still feel noisy? Many people believe that a high STC (Sound Transmission Class) rating means that no sound can pass through a wall, but STC measurements focus primarily on mid-range and high frequencies. This means that low-frequency sounds, such as traffic noise or bass sounds from speakers, can penetrate much more than the STC value suggests!

An STC value of 40 may mean that normal speech can still be heard through the wall, while a value of 60 means that almost all sound disappears. But sound insulation is not just about numbers – the building's materials, joints and transitions between walls, floors and ceilings affect the end result more than you might think.

An STC calculator can help you predict sound insulation before you build – but it cannot take actual leakage points into account! If a wall has the slightest gap around electrical outlets or ventilation, sound can penetrate as if the wall were barely there. Therefore, both theoretical calculations and practical measures such as sealing strips and damping materials are required to truly achieve the desired sound reduction.

So next time you use an STC calculator, remember that the value is only a guideline. In reality, small details can make a huge difference to how much sound is actually blocked!