Sound insulation plays a central role in modern construction. It contributes significantly to living comfort and influences how rooms are perceived acoustically. Inadequate sound insulation is usually noticed immediately and perceived as disturbing. Careful planning is therefore essential, especially in timber construction, where the lightweight construction method places special demands on sound insulation.
This technical article explains the basics of sound insulation and describes the special challenges that this phenomenon poses in timber construction. In addition, SonoTec V2 line bearings are presented as a tried-and-tested solution that can be used to reduce flanking noise in a targeted and proven manner.
Contents: Sound insulation in construction | What is sound? | Representation of sound transmission | Types of sound in construction | Sound reduction measures in timber construction | Flanking sound in timber construction | SonoTec V2 line bearings | Conclusion
The term “sound” describes noises that physically occur as vibrations or waves. These propagate through air, solids, or liquids and can be transmitted from their source to other rooms. In construction, the main focus is on minimizing unwanted sound transmission.
Sound insulation describes all structural, technical, and design measures intended to prevent sound from traveling from one room to another or causing disturbance in a room.The aim is to reduce the transmission of unwanted noise, whether through mass, decoupling, insulation materials, or well-designed construction methods
A sound source (in this case, a tuning fork) causes the surrounding air molecules to vibrate, thereby generating sound waves.
These collide with their neighbors, causing compressions and rarefactions in the air. This process is called sound transmission.
1. Airborne sound
Airborne sound is created when noises are transmitted directly through the air, for example through speech, music, television, or road traffic. Airborne sound is mainly transmitted via the flanks (walls), as shown in the following diagram:
Transmission paths:
Ceiling - ceiling Dd (1x)
Ceiling - flank Df (4x)
Flank - ceiling Fd (4x)
Flank - flank Ff (4x)
→13 transmission paths mainly transmitted via the flanks. Sound insulation in building construction is achieved using components such as walls, ceilings, or windows, which are designed to allow as little airborne sound as possible to pass through. The following factors are crucial:
Examples of measures for airborne sound reduction:
Decoupling of the edges (e.g., using Sonotec V2)
Appropriate floor construction
Suspended ceilings
2. Impact sound & structure-borne sound
Impact sound is caused by mechanical effects on building components, e.g., footsteps, children playing, falling objects, or moving furniture. This sound propagates through solid bodies (structure-borne sound) and is mainly transmitted through the ceiling, as shown in the following diagram:
Ceiling - Ceiling Dd (1x)
Ceiling - Flank Df (4x)
→ 5 Transmission paths mainly via the ceiling.
Examples of measures that achieve good impact sound insulation:
The timber construction industry has been experiencing an enormous boom in many areas for some time now, whether in the form of single-family homes or multi-story urban residential buildings. Modern timber construction systems are an essential basis for this and offer excellent structural and ecological properties. However, sound insulation is one of the biggest challenges in this area.
But why is sound insulation so challenging in timber construction?
Since wood is a lightweight building material and therefore has a low mass, this means higher sound transmission and, at the same time, greater demands on layers, decoupling, and joint technology. For this reason, multi-layer components are often used in timber construction to efficiently reduce airborne and impact sound. The decoupling of flanking sound plays a central role here.
Currently, sound insulation for buildings is calculated in most cases using DIN 12354. However, the problem is that this standard is intended for concrete construction and, according to experts, is highly inaccurate (up to 5 dB deviation). Our solution was therefore to work with experts such as Prof. Dipl.-Ing. Dr. Anton Kraler from the University of Innsbruck to create a realistic and practical test setup. Thanks to our tests, there is no need for complicated calculations based on an incorrect standard. As long as the correct weights are used, a value of 6-7 dB can always be planned for R'w (real airborne sound insulation index).
Kij and why we do not use this value Most suppliers of sound insulation products specify the impact sound insulation index Kij as the sound reduction value. This is tested in the laboratory
by setting up a structure as shown in Figure 1 and measuring the sound transmission via the joints (K13, K23, K12 in the example). However, as can be seen in the figures for airborne and impact sound, sound is transmitted not only via the joints, but also via a wide variety of transmission paths. Therefore, although the Kij value provides a good guide, it is always only an approximate value. According to DIN 4109 Supplement 2 (2018) and EN 12354-1 (Annex E), when transferring laboratory values to construction practice, a margin of at least 2 dB, and in unfavorable cases up to 5 dB, must be taken into account.
Even then, the Kij remains only a rough guide. In contrast, our R'w and L'n,w values from the tests Even then, the Kij remains only a rough guideline. In contrast, our R'w and L'n,w values from the tests on the test bench provide real values that are reliable for planning purposes.
SonoTec V2 line bearings enable targeted reduction of sound transmission at the flank. Six variants with different degrees of hardness up to 58 Shore A allow use even with high loads, for example in multi-story timber construction. The line bearings are versatile and suitable for constructions made of CLT, glulam, LVL, and for connections to steel and concrete.
With SonoTec V2 line bearings, we offer a practical and tested solution for reducing airborne sound in timber construction. The decisive factor here is that SonoTec V2 is based on real-world practical tests and the sound insulation values determined from these tests have been verified not only mathematically, but also in a realistic building structure. This provides a real sound insulation value R'w that enables a reduction in airborne sound of up to 7 dB.
SonoTec V2 linear bearings are designed to specifically reduce sound transmission along the flange. Six variants with different degrees of hardness up to 58 Shore A allow them to be used even under high loads, for example in multi-storey timber construction. The linear bearings are highly versatile and are suitable for structures made of CLT, glulam and LVL, as well as for connections to steel and concrete.
When using the SonoTec V2, CLT angles do not require additional decoupling!
We were able to prove this through our practical tests, which revealed several advantages:
→ Fewer angle brackets required
→ Less working time
The line bearings are made of high-quality EVA-based thermoplastic polymer (ethylene vinyl acetate copolymer) and combine elasticity, durability, and dimensional stability. The material's properties are crucial for sound insulation: it must be soft in order to absorb and compensate for vibrations and sound, otherwise there is no sound insulation.
SonoTec V2 line bearings also remain permanently elastic and have passed the compression set test in accordance with DIN 844. This ensures reliable sound decoupling over many years.
Sound insulation poses a particular challenge in modern timber construction, requiring specific planning. The low mass of timber components can promote sound transmission, meaning that conventional solutions are often insufficient.
SonoTec V2 line bearings offer a practical solution for such applications, delivering real, proven sound insulation values to effectively minimize noise. The tested R'W values provide a high degree of planning reliability, as there is no need for mathematical assumptions and additional safety factors. This not only simplifies the design of the construction, but also contributes to reliable compliance with sound insulation requirements.
In addition to suitable products for timber construction projects, however, sound planning is crucial for effective sound insulation. That is why Eurotec provides individual support to planners and contractors in the sound insulation planning process for their projects.
We plan for you!
Of course, you can also use our product documentation to determine which Sonotec V2 strips you need, but we offer you a quick and easy service.
What we need:
What you get:
A detailed list of the required strips
Building plan with colored strips so that you can see where each strip belongs on the construction site.
Building with CLT
Take a look at our catalog specifically on the topic of “Building with CLT.” Get detailed information on this forward-looking construction method and an overview of our fasteners for structural timber construction.
Planning sound insulation with confidence
Sound insulation in timber construction requires professional experience, technical expertise, and reliable evidence. Our specialized team performs sound insulation calculations directly and provides project-specific support throughout all phases.
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