Soundproofing Shared Walls: Experiences & Best Solutions

How is noise generated through the neighboring wall?

To choose the right soundproofing for your wall to the neighbor, you should first understand how sound is transmitted. Basically, acousticians distinguish between two transmission paths:

Airborne sound is created by sound waves in the air – for example through conversations, music, or television noise. These waves hit the wall, cause it to vibrate, and release the sound on the other side. The more massive and heavier a wall is, the less it vibrates and the better it insulates airborne sound. A 24 cm thick concrete wall offers significantly better sound insulation than an 11.5 cm thin plasterboard wall.

Structure-borne sound, on the other hand, is transmitted directly through solid materials. If your neighbor drops a heavy object on the floor or moves furniture, the vibration spreads through the entire building structure. Structure-borne sound can hardly be influenced by retrofitting wall insulation – only decoupling such as floating screeds or resilient mountings help here.

In most living situations, airborne sound is the main problem. Conversations, music, and television noises from neighbors are transmitted through inadequately insulated walls. This is exactly where modern soundproofing solutions come into play.

Legal requirements for sound insulation between apartments

In Germany, DIN 4109 regulates the minimum requirements for sound insulation in building construction. For apartment partition walls, it prescribes a rated sound reduction index of at least 53 decibels. This means: A partition wall must reduce noise by at least 53 dB.

For comparison: A normal conversation generates a sound level of about 60 dB. If the wall dampens this sound by 53 dB, only 7 dB reach the neighbor – barely noticeable. However, DIN 4109 was designed for new buildings. Old buildings with thin walls often do not achieve these values.

If your neighboring wall falls short of the legal requirements, you as a tenant may be able to claim a rent reduction. As an owner, you have the option of retrofitting better sound insulation to the neighbor – either through structural measures or through absorbing wall coverings.

Structural measures: Facing shells and double walls

The most effective, but also most complex method for soundproofing the wall to the neighbor is the construction of a facing shell (Vorsatzschale). A second wall is placed in front of the existing wall – either as a solid masonry wall or as a stud wall made of metal profiles with plasterboard.

How the facing shell works

A facing shell works according to the mass-spring-mass principle: The existing wall forms the first mass, the cavity in between acts as a spring (often filled with insulation wool), and the new wall layer forms the second mass. This system acoustically decouples the two wall layers from each other and prevents vibrations from being transmitted directly.

With a professionally executed facing shell, the sound reduction index can be improved by 10 to 20 decibels. A wall that originally only insulated 45 dB thus achieves the required 53 dB or even significantly more. However, there are also disadvantages:

The loss of space is at least 8 to 12 centimeters per wall. In small rooms, this can be significant. The costs for material and craftsmen are typically between 100 and 200 euros per square meter – for a 10 m² wall that's 1,000 to 2,000 euros. In addition, as a tenant you need the landlord's permission, and the construction work is associated with dirt, noise, and several working days.

When is a facing shell worthwhile?

Structural soundproofing to the neighboring wall is especially worthwhile in cases of extreme noise pollution and if you are the owner or plan to stay in the apartment long-term. If you are renovating or gutting the apartment anyway, you can plan the measure right away. For tenants or in cases of moderate noise pollution, absorbing wall coverings are the more practical alternative.

Acoustic panels as flexible soundproofing for the neighboring wall

Modern acoustic panels offer an attractive solution for anyone who wants to soundproof their wall to the neighbor without structural intervention. Unlike solid facing shells, these panels work primarily with sound absorption: They swallow the sound waves before they can be reflected by the wall, thus significantly reducing the overall volume in the room.

How does sound absorption work?

When sound waves hit a hard surface like a concrete wall, they are almost completely reflected. The sound bounces back and forth, builds up, and creates the typical echo in unfavorable rooms. Acoustic panels made of porous material – such as highly compressed polyester felt – convert the sound energy into minimal heat through friction. The sound waves penetrate the material, are "trapped" there, and lose their energy.

High-quality acoustic panels achieve a sound absorption coefficient (αw) of 0.9. This means: They absorb up to 90 percent of the incoming sound energy. Only 10 percent is reflected. This value applies in particular to medium and high frequencies – exactly the range in which speech and most everyday noises lie.

Felt acoustic panels: The self-adhesive solution

For tenants and anyone who prefers uncomplicated installation, self-adhesive felt acoustic panels are the first choice. These panels consist of recycled PET felt with a density of 2000 g/m² – significantly denser than many competing products. The high compression ensures better absorption values and longer durability.

The panels measure 30 x 30 cm with a thickness of 15 mm and are delivered in a set of 9, which covers 0.81 m². The self-adhesive back sticks to practically all surfaces – wallpaper, plaster, wood, tiles, even glass. Particularly important: The panels can be removed without leaving any residue if you move out or want to redecorate. This makes them the ideal soundproofing for the wall to the neighbor in rental apartments.

In terms of color, the panels are available in subtle tones: gray, white, sky blue, and royal blue. The square shape with straight edges allows for a seamless arrangement – unlike hexagonal honeycomb patterns, which often leave gaps. You can cut the panels as needed with a utility knife to leave out sockets or light switches.

Wood acoustic panels: Design meets function

If aesthetics are particularly important to you, wood acoustic panels offer an elegant alternative. These panels combine the absorption effect of highly compressed felt (1500 g/m²) with the sound-scattering effect of real wood slats. The result is a double acoustic effect: The slats break the sound and distribute it diffusely in the room, while the underlying felt absorbs it.

Each panel measures 120 x 60 cm with a total thickness of 21 mm (12 mm wood slats plus 9 mm felt). With a weight of 5.2 kg per panel, they are significantly heavier than pure felt panels and therefore require a more stable mounting. Installation is done with mounting adhesive, screws, or nails – these panels are not self-adhesive due to their weight.

The real wood veneer comes from FSC-certified, sustainable forestry and is available in several variants: Oak/Gray, Oak/Black, Walnut/Black, Pear/Black, and Techwood/Black. The natural wood look visually enhances any room and can be easily combined with modern or classic furnishing styles.

Wall protection acoustic felt: Dual function for special areas

A special solution for areas that require both soundproofing and mechanical protection is the wall protection acoustic felt. These large-format panels (118 x 59 cm) with 9 mm thickness and 1500 g/m² density serve as impact protection and sound absorber at the same time – for example behind beds, in garages, or in the hallway.

The impact-resistant surface protects the wall from scratches and dents, while the felt structure absorbs up to 80 percent of the noise. These panels are also self-adhesive, removable without residue, and water-repellent. They are particularly suitable for soundproofing the neighboring wall if you also want to place furniture against the wall that would otherwise leave marks or damage.

How much soundproofing do you really need?

The question of the required amount of acoustic panels cannot be answered across the board – it depends on several factors:

Wall size and room volume: The larger the room, the more absorbing surface you need for a noticeable effect. As a rule of thumb: At least 15 to 20 percent of the wall surface should be covered with acoustic panels to achieve a significant improvement. For a 10 m² neighboring wall, this would be about 1.5 to 2 m².

Type of noise pollution: High-frequency noises like voices, music, or television can be dampened very well with acoustic panels. Low-frequency noise like bass booming or impact sound additionally requires massive insulation, as absorption alone is less effective here.

Existing room acoustics: In a room with many hard surfaces (tiles, glass, concrete), the effect of acoustic panels is greater than in a room already equipped with carpets, curtains, and upholstered furniture. If you currently have no textile elements at all, you will notice the improvement from acoustic panels particularly clearly.

In practice, it shows: Even 2 to 3 square meters of high-quality acoustic panels on the neighboring wall can noticeably reduce the noise level. Conversations become more muffled, music less penetrating, and the general quiet in the room increases. For optimal results, a combination of wall panels and additional elements on the ceiling or opposite walls is recommended.

Installation of acoustic panels: How to do it right

The installation of acoustic panels is uncomplicated in most cases and requires no special tools. Nevertheless, there are a few points to consider in order to achieve optimal results.

Preparation of the wall surface

Before you attach acoustic panels, the wall should be clean, dry, and free of grease. Dust and loose paint residues impair the adhesion of self-adhesive panels. Wipe the surface with a slightly damp cloth and let it dry completely. For heavily textured wallpaper or rough plaster, it may make sense to smooth the surface beforehand or apply a primer.

Planning the layout

Think in advance about how you want to arrange the panels. For even sound absorption, an extensive distribution over the entire neighboring wall is recommended. If you are working with limited space, concentrate the panels on the areas closest to the neighbor – for example, at head height in the living room or behind the sofa.

With square felt panels, you can work with a checkerboard pattern, staggered rows, or a continuous surface. Wood acoustic panels can be mounted horizontally, vertically, or in combination. Some users deliberately set accents by only covering part of the wall – for example, as a decorative strip at eye level.

Installation of self-adhesive panels

Self-adhesive acoustic panels are particularly easy to handle. Peel off the protective film from the back, position the panel in the desired location, and press it on firmly. Start in the middle and work your way to the edges to avoid air bubbles.

The adhesive strength develops fully within 24 hours. During this time, you should not put any load on the panels. For cool walls (below 15 °C), it can be helpful to slightly warm the wall beforehand – for example with a hairdryer – to improve adhesion.

Installation of wood acoustic panels

Due to their weight, wood acoustic panels require a more stable mounting. The simplest method is mounting adhesive, which is applied to the back of the panel. Make sure to distribute the adhesive evenly, especially at the edges and in the middle. Press the panel firmly and prop it up for a few minutes if necessary until the adhesive sticks.

Alternatively, you can attach the panels with screws or nails. This allows for residue-free removal if you want to take the panels down later. To do this, drill holes in the corners of the panel and screw it to the wall with suitable dowels. The screw heads can be concealed with small wooden plates or colored pencils.

Costs of soundproofing the neighboring wall at a glance

The costs for soundproofing to the neighbor vary significantly – depending on whether you choose structural measures or acoustic panels. Here is a detailed comparison:

Structural soundproofing (facing shell)

A professionally built facing shell costs between 100 and 200 euros per square meter, including materials and craftsmanship. For a typical living room wall of 10 m², you have to reckon with 1,000 to 2,000 euros. Added to this are possible costs for electrical work (relocating sockets), painting work, and disposal of rubble. The total costs can quickly reach 2,500 to 3,000 euros.

In return, you get a permanent, highly effective solution with sound insulation of 10 to 20 decibels. If you are the owner and plan to stay in the property long-term, this investment can pay off – especially in extreme noise pollution situations.

Acoustic panels made of felt

Self-adhesive felt acoustic panels are significantly cheaper. A set of 9 covering 0.81 m² costs 38.90 euros. For a 10 m² wall, you need about 12 sets, so around 467 euros. There are no additional costs – no craftsmen, no permits, no ancillary work. Installation takes less than an hour and can easily be done yourself.

However, the insulation effect is lower than with a facing shell. While a massive double wall reduces sound by 10 to 20 dB, acoustic panels lower the noise level in the room by about 5 to 10 dB – depending on the quantity and placement. For most living situations, however, this is completely sufficient to achieve a noticeable improvement.

Wood acoustic panels

Wood acoustic panels lie price-wise between the two extremes. A set of 2 covering 1.44 m² costs 109.90 euros. For 10 m², you need about 7 sets, so around 769 euros. In addition, there are low costs for mounting adhesive (approx. 10 to 20 euros) or screws and dowels.

Besides the acoustic effect, the wood panels offer a significant visual added value. They aesthetically enhance the room and look more high-quality than pure felt panels. If design is important to you and you are willing to invest a little more, wood acoustic panels are an excellent choice.

Cost-benefit conclusion

For tenants and anyone looking for a flexible, affordable solution, self-adhesive felt panels are the best choice. They cost less than a tenth of a structural measure, can be removed without leaving a trace, and still offer a noticeable improvement in room acoustics. Owners who want to invest long-term can achieve even better results with wood acoustic panels or a facing shell – depending on their budget and requirements.

Practical tips for maximum effect

To optimize the soundproofing of your wall to the neighbor, you should consider a few additional measures:

Combination with other elements: Acoustic panels work best in combination with other sound-absorbing materials. Carpets, curtains, upholstered furniture, and bookshelves also contribute to sound damping. A large carpet on the floor reduces impact sound, heavy curtains on the windows dampen outside noise, and a packed bookshelf on the neighboring wall acts as additional mass.

Place furniture strategically: Place heavy pieces of furniture like cabinets, shelves, or sofas against the neighboring wall. They act as an additional barrier and absorb part of the sound before it enters the room. Make sure to leave some distance between the furniture and the wall so the acoustic panels can unfold their effect.

Seal gaps and cracks: Sound also penetrates through the smallest openings. Check sockets, light switches, and door frames for gaps and seal them with acrylic or foam. Sockets in lightweight walls are often weak points through which sound penetrates unhindered. Special soundproof sockets can help here.

Bilateral measures: If you have a good relationship with your neighbor, talk to them about the topic. Perhaps they are also interested in an improvement. Acoustic panels on both sides of the wall double the effect and benefit both parties. Such solutions can often be implemented together – for example, by sharing the costs.

Legal aspects: What are tenants allowed to do?

As a tenant, you basically have the right to design your apartment according to your own ideas – as long as you do not make any structural changes and restore the original condition when you move out. Self-adhesive acoustic panels fall into this category, as they can be removed without residue and do not leave any drill holes.

The situation is different for wood acoustic panels that are attached with screws or nails. Drill holes are considered a change to the rental property and usually have to be filled and painted over when moving out. If you want to play it safe, use mounting adhesive instead of screws – or get written permission from the landlord.

Important: You are not allowed to drill through load-bearing walls or damage the building structure. If you are unsure, you should talk to your landlord before installation. Many landlords are accommodating if you explain that the measure serves to reduce noise and can be dismantled.

When are acoustic panels not enough?

As effective as acoustic panels are – they have their limits. In the following situations, you should consider additional or alternative measures:

Extreme noise pollution: If your neighbor regularly throws loud parties, operates a music system with strong bass, or argues loudly at night, acoustic panels alone are not enough. In such cases, structural soundproofing with a facing shell or legal clarification (noise protection ordinance, house rules) is necessary.

Low-frequency noise: Basses and low-frequency vibrations penetrate walls more easily than high-frequency noises. Acoustic panels primarily absorb medium and high frequencies. They only help to a limited extent against booming basses. Massive insulation layers or decoupled constructions are required here.

Structure-borne sound: If the noise is not transmitted through the air but through the building structure – for example, impact sound from the neighbor above or vibrations from machines – wall panels do not work. Structure-borne sound requires decoupling such as floating screeds, impact sound insulation, or resilient mountings.

In these cases, you should consult an acoustician or building expert. They can carry out sound measurements, analyze the causes, and suggest targeted solutions.

Sustainability and material quality of acoustic panels

When buying acoustic panels, you should not only pay attention to the acoustic effect but also to the material quality. High-quality panels are made of recycled PET felt, which is obtained from old plastic bottles. This felt is pollutant-free, odorless, and 100 percent recyclable.

The panels from Aeco Sound® contain more than 60 percent recycled material and thus contribute to conserving resources. The surfaces are sealed to be water-repellent, so dust and dirt can easily be removed with a damp cloth. Unlike cheap foams or convoluted foams, high-quality PET felt panels do not outgas and do not pollute the indoor air with harmful substances.

The wood acoustic panels also meet high sustainability standards. The real wood veneer used comes from FSC-certified forestry, which pays attention to responsible forest management. The MDF carrier boards are low in emissions and comply with emission class E1.

Practical experiences: What users report

Many users who have used acoustic panels to soundproof their wall to the neighbor report clearly noticeable improvements. Typical feedback is:

"Ever since we installed the felt panels on the wall to the neighbor, we hear significantly less from next door. We used to be able to understand every word, now it's just a quiet murmur."

"The wood panels not only look great, but they have also massively improved the acoustics in our living room. The echo is gone, and the noises from the neighbor have become much quieter."

"We installed the panels ourselves – took less than an hour. And the difference is truly amazing. Finally, we can watch TV in peace again without constantly having to adjust the volume."

It's important to have realistic expectations: Acoustic panels do not completely eliminate neighbor noises, but they reduce them significantly and create a more pleasant, quieter living atmosphere. Those expecting absolute silence will be disappointed – those looking for a noticeable improvement will find it.

Conclusion: The right solution for your situation

Soundproofing the wall to the neighbor is a common concern that can be solved in various ways. Structural measures like facing shells offer the highest insulation effect, but are expensive, complex, and often unfeasible for tenants. Acoustic panels represent a practical, cost-effective alternative that can be implemented without permission and on your own.

Self-adhesive felt acoustic panels are particularly suitable for tenants, as they can be removed without residue and leave no drill holes. With a density of 2000 g/m² and an absorption coefficient of 0.9, they offer high acoustic effectiveness with minimal effort. The costs are around 50 euros per square meter – a fraction of what a structural measure costs.

Wood acoustic panels combine acoustic function with high-quality design. They scatter and absorb sound at the same time and visually enhance the room. Costing around 75 euros per square meter, they are in the mid-price segment and are suitable for anyone who values aesthetics.

Regardless of the chosen solution, the following applies: The sooner you act, the faster your quality of living improves. Noise from neighbors is not a fate you have to accept. With the right measures, you can create a space where you feel comfortable again – quiet, relaxed, and undisturbed.