How do you soundproof and insulate doors?

Soundproofing and insulating a door is one of the most effective measures for reducing sound transmission between rooms or between indoor and outdoor environments. Whether the goal is to create a quieter working environment, improve the acoustics in your home, or reduce disturbing noise from traffic and neighbors, the right door insulation can make a big difference. Doors are often one of the weakest points in a soundproofed construction, as sound easily penetrates gaps in the door frame, threshold, and the door leaf itself.

To achieve effective sound insulation, the door should be addressed on several levels. One of the most important factors is to prevent sound leakage by ensuring a tight construction. This can be done by applying sealing strips along the edges of the door and installing an automatic threshold or a sound-insulating threshold seal. Eliminating gaps significantly reduces sound leakage, and even small openings can have a major impact on how much sound is allowed to pass through.

Another important aspect of sound insulation is the construction of the door leaf itself. Thin, hollow doors allow significantly more sound to pass through compared to solid doors. If possible, a lightweight interior door should be replaced with a solid core door, such as a solid wood door, a fire-rated door, or a door with a special sound-insulating core. If a door with a thinner construction must be retained, it can be supplemented with a soundproof door panel or sound-absorbing panel to increase density and reduce sound transmission.

For additional sound absorption, sound-absorbing materials can be installed on the door surface. Acoustic foam, sound-absorbing fabric, or sound-absorbing felt mats can help reduce sound reflections and improve room acoustics. This is particularly useful in recording studios, home theater systems, or other environments where you want to minimize reverberation and noise.

Soundproofing doors has several advantages, both from a comfort and energy efficiency perspective. A quieter environment increases concentration and well-being, which is especially important in work environments or homes where you want to create a peaceful atmosphere. For office spaces and businesses, effective soundproofing of doors can improve the working environment and thus increase productivity. In addition, a well-sealed door contributes to better energy efficiency by preventing heat loss and drafts, which in turn can lead to lower heating and cooling costs.

In summary, sound insulation and soundproofing of doors is an important measure for improving the sound environment in various types of buildings. By sealing the edges of the door, using sound-absorbing materials, and choosing a solid door type, you can effectively reduce sound transmission and create a more comfortable and soundproof environment, whether in your home, office, or public spaces. With the right measures, you can achieve significant noise reduction and improve sound comfort in your daily life.

Here are some advantages of soundproofing and sealing doors and door frames

Create a quieter indoor environment
One of the main advantages of soundproofing a door is to reduce sound transmission between rooms. This is particularly important in homes where privacy is desired, but also in work environments where sound insulation can improve concentration. In offices, conference rooms, or home offices, a soundproof door can help reduce disturbing noise from the surrounding environment and create a more productive workplace.

Improved working environment and increased concentration
Noise disturbances can have a major impact on the working environment and lead to reduced concentration and productivity. By soundproofing doors and sealing door frames, unwanted noise from conversations, computers, telephones, or other activities can be reduced. This is particularly beneficial in open-plan offices, schools, and libraries, where a quiet working environment is crucial for focus and efficiency.

Energy efficiency and reduced heat loss
Sealing doors and door frames not only contributes to better sound insulation, but also to a more energy-efficient building. By eliminating gaps and cracks, heat loss is prevented, which helps to maintain a stable indoor temperature. This reduces the need for heating and cooling, which in turn leads to lower energy costs and a more sustainable building.

Protection against moisture and drafts
A tight door also acts as a barrier against moisture and drafts, which can be crucial for maintaining a healthy indoor environment. By preventing cold air and moisture from entering, problems such as mold growth, temperature variations, and poor air quality can be avoided. This is especially important in properties where climate control and air quality are high priorities.

In homes and workplaces located near roads, train stations, or other noisy areas, soundproofing doors can have a significant effect. By combining soundproofing materials with effective sealing of the frame and threshold, noise from traffic, neighbors, and other external sources can be significantly reduced. This leads to a quieter and more comfortable indoor environment.

Extended door life and reduced wear
When a door is poorly sealed, vibrations and friction can occur every time it is opened and closed. With the right sound insulation and sealing, the load on the door's suspension and hinges is reduced, which extends the door's service life and reduces the need for maintenance. This makes sound insulation and sealing a long-term investment that both improves comfort and saves money on repairs.

Sound insulation, soundproofing, and sealing the inside of a door

Option 1 - The best way, in our opinion, to soundproof the inside of a door

Soundproofing a door from the inside is an effective method of reducing sound leakage between rooms. An inadequately sealed door can let through a lot of sound, especially if it is hollow. By using the right materials and methods, you can create a significantly quieter environment, whether it is an office, bedroom, or recording studio.

Check the door's construction

Before you begin soundproofing, it is important to determine what type of door you have. A solid door already has better sound insulation than a hollow door, but if you find that sound is leaking through, it is likely that the door has a hollow core. These doors often consist of a lightweight filling, such as a honeycomb structure of paper or cellular plastic, which makes them less effective at blocking sound. If you have a hollow door, you can soundproof it by replacing the filling and installing sound-absorbing material on the inside.

If you have a hollow door, you can soundproof it by replacing the filling and installing sound-absorbing material on the inside.

Step 1 – Dismantling the door

1. Remove the handle, lock, and other fittings to gain full access to the door.

2. Clean the door surfaces to ensure that no dust or dirt residues affect the installation of sound-absorbing material.

3. Remove one side of the door, preferably the side facing the room where you want to reduce the noise level. If the purpose is to prevent outside noise from entering, you can work on the other side instead.

4. Remove the existing filling inside the door. This is usually a honeycomb structure made of paper or cellular plastic, which does not provide effective sound insulation.

Step 2 – Installing soundproofing material

5. Clean the inside of the door so that the surface is completely free of dust and dirt before you start installing soundproofing material.

6. Reinforce the inside of the door if necessary and if there is enough space. This can contribute to a more stable construction and improved sound insulation.

7. Install SilentDirect Polaric damping mat or SilentDirect MLV on the entire inside of the door, including the removed door panel. It is important to ensure that the damping mat covers as much as possible and that no air gaps are formed.

Step 3 – Add a sound-absorbing layer

8. Install either SilentDirect Egg or SilentDirect Neo on top of SilentDirect Polaric. Which option you choose depends on the desired sound insulation and how much extra thickness the door can accommodate. SilentDirect Neo in 7 mm is a common recommendation as it provides good sound insulation without affecting the door's function.

Step 4 – Reinstalling the door panel

9. Reinstall the wooden panel that you previously removed from the door. Make sure it is securely fastened to maintain the stability of the door.

10. Reinstall the handle, lock, and other fittings. Check that all parts are in place and that the door can be opened and closed without any problems.

11. If necessary, you can sand and repaint the door to restore its original appearance and ensure a neat finish.

Once everything is ready, you can enjoy a significantly quieter environment, where sound leakage through the door has been minimized.

Sound insulation, soundproofing, and sealing the outside of a door

Option 2 - Soundproof one side of the door

Soundproofing and sealing the outside of a door is an effective method of reducing sound leakage and improving the sound environment in a room. If the door cannot be replaced with a solid soundproof door, optimized soundproofing of the outside is a good alternative. By applying sound-absorbing material, sound hitting the door can be absorbed instead of reflected, reducing both noise and resonance.

Step 1 – Preparation and cleaning

1. Remove handles, locks, and other fittings to ensure that the entire surface of the door is accessible.

2. Clean the door thoroughly to remove dirt and grease. A clean surface is essential for the soundproofing materials to adhere properly.

Step 2 – Installation of soundproofing materials

3. Apply SilentDirect Polaric damping mat or SilentDirect MLV over the entire surface of one side of the door, but make sure it is the side that does not touch the door frame. Leave space for the handle and lock so that the door's functionality is not affected. For best results, it is important to seal all joints with a suitable sealant, such as SilentDirect Seal, to eliminate any sound leaks.

Step 3 – Add a sound-absorbing layer

4. Install SilentDirect Neo or SilentDirect Egg on top of SilentDirect Polaric. Which product and thickness you should choose depends on how much extra depth the door can handle. A standard door has a thickness of 35–40 mm, so we usually recommend using 15 mm or 25 mm of SilentDirect Neo or SilentDirect Egg. Creating a small air gap between the layers further improves sound insulation.

Step 4 – Adjustment and installation of new surface board

5. Cut a new panel to cover the sound insulation and fit the door dimensions. If you want to achieve a neater finish, you can build a frame around one side of the door in step 1 and install the sound insulation inside this frame, which provides a more uniform and stylish solution. Don't forget to make new holes in the panel for handles, locks, and any other fittings.

Step 5 – Reassembly and final adjustments

6. Reinstall the handle, lock, and other fittings. Depending on the increased thickness of the door, it may be necessary to extend or replace certain parts.

7. If you want to give the door a new and uniform look, you can sand and repaint it after the sound insulation has been installed.

Once everything is complete, you can enjoy a significantly more soundproof environment where sound leakage through the door has been minimized.

Sealing of door frame and threshold for optimal sound insulation

One of the most important factors for effective sound insulation is to eliminate gaps and create a completely sealed door frame and threshold. Even the smallest gap can allow sound to penetrate, reducing the effectiveness of other soundproofing measures. By carefully sealing all joints between the door frame, wall, and threshold, sound transmission can be significantly reduced while improving the energy efficiency of the building.

Seal between door frame and wall

1. With a weatherstripping strip
To achieve effective sound insulation between the door frame and wall, it is important to fill the space between these surfaces with a sound-absorbing and stable material. One of the most proven methods is to use a mineral wool filler strip, which creates a barrier that both reduces sound transmission and improves the building's energy efficiency.

Caulking involves filling a 10–15 mm space between the frame and the wall with a loosely packed strip of mineral wool. It is important that the material is not pressed too hard, as compact packing can reduce its sound-absorbing properties.

Once the caulking has been completed, the inside of the joint is sealed with a bottom strip, which creates an additional sound-insulating barrier. To prevent moisture penetration and ensure a long-lasting seal, the work is finished with vapor barrier tape or joint sealant, which creates an effective moisture and diffusion barrier into the room.

This method ensures that the door frame is properly sealed, contributing to both better sound insulation and improved energy efficiency in the building.

2. With expanding tape
Another effective method for sealing the space between the door frame and the wall is to use expanding joint tape, also known as swelling tape. These specially developed seals are designed to expand on contact with moisture, making them particularly effective for creating a tight and sound-insulating seal.

How do expansion strips work?
Expansion strips are made of flexible materials such as polyurethane or silicone and are initially compressed during installation. When exposed to humidity or rain, they expand and fill in gaps and unevenness between the door frame and the wall.

This expanding property allows the expansion strips to effectively create a tight seal that prevents air and water leakage. This not only contributes to better sound insulation but also improves the energy efficiency of the building by minimizing heat loss.

Advantages of expansion strips
One of the major advantages of expansion strips is their versatility. They can be used for both window and door frames and are an ideal solution for reducing sound transmission in various types of structures. As they adapt to the space in which they are installed, they create a comprehensive seal that also protects against weather conditions and temperature variations.

By preventing moisture and cold air from entering, expansion strips help to create a more comfortable indoor environment. In addition, they act as an extra protective barrier against draughts, further improving the comfort of the room.

Correct installation is crucial
To get the maximum effect from expansion strips, it is important to follow the manufacturer's instructions and ensure that the strip is correctly dimensioned for the specific space. A correctly installed seal will contribute to both improved sound insulation and energy efficiency, while protecting the door frame from moisture and temperature differences.

Expansion tape is a long-term and effective solution for those who want a durable, self-adjusting, and sound-insulating seal between the door frame and the wall.

3. With joint foam
Joint foam is one of the fastest and most effective methods for sealing the space between the door frame and the wall. It is mainly used when installing new door frames, where it quickly fills the gap and creates a stable, sound-absorbing, and insulating barrier.

Joint foam is applied by spraying the expanding mass into the joint. As the foam expands, it fills in all small gaps and unevenness, preventing both sound and air leakage. This method provides a tight and durable seal that improves both sound insulation and energy efficiency.

Important to consider when using joint foam
When sealing exterior doors, extra control over the foam is required, as there must be space to seal the joint on both sides. Joint foam alone is not sufficient as a sealant and should be supplemented with a flexible sealant on the inside and outside to ensure long-term durability.

Joint foam is also convenient to use for sealing small cracks and gaps, for example in baseboards or at floor level where sound can penetrate.

Complement with SilentDirect Seal for maximum effect
Regardless of the method used to seal the door frame, we recommend that SilentDirect Seal be installed between the door frame and the wall before the lining is installed. SilentDirect Seal is available in several widths and thicknesses, making it possible to customize the seal as needed and ensure optimal sound insulation.

By combining joint foam with SilentDirect Seal, you get a complete and long-lasting sound and airtight seal that contributes to a quieter and more energy-efficient indoor environment.

Sealed under the threshold for optimal sound insulation and energy efficiency

Sealing under the threshold is a crucial part of soundproofing a room. If the threshold is not properly sealed, sound, draughts and dust can penetrate through gaps and impair both sound comfort and the indoor climate. Proper sealing reduces sound leakage, improves energy efficiency and contributes to a more comfortable living or working environment.

Effective methods for sealing under the threshold
To achieve a tight and soundproof solution under the threshold, we recommend using sealing compound or mounting adhesive that also acts as a seal. These products fill in any unevenness between the threshold and the floor and create a flexible but durable barrier against sound, moisture, and air leakage.

Another effective alternative is to use SilentDirect Seal sealing strip under the threshold. This sealing strip is available in several widths and thicknesses, making it possible to adapt the seal to the specific dimensions and needs of the threshold. SilentDirect Seal creates a powerful sound-absorbing and vibration-insulating effect while preventing cold air and dirt from entering.

The advantages of a well-sealed threshold
Sealing under the threshold reduces sound transmission between rooms, which is particularly important in homes, offices, and public environments where sound comfort is a priority. A sealed threshold also prevents cold air and drafts from entering, contributing to better energy efficiency and lower heating costs. In addition, the seal protects against dust and dirt, improving the indoor environment and reducing the need for maintenance.

A well-executed seal ensures that the entire door construction functions optimally and complements other soundproofing measures, such as sealing the door frame and installing sound-absorbing material on the door.

Sealing strip between door and door frame for optimal sound insulation

One of the most effective measures for reducing sound transmission through a door is to seal the gap between the door and the door frame. Gaps in the door gap allow sound to pass freely, which impairs both sound comfort and acoustic privacy between rooms. Installing a high-quality sealing strip creates a barrier that effectively reduces sound leakage and improves the door's sound-insulating properties.

SilentDirect Seal – An effective sealing solution
To achieve the best possible seal, we recommend SilentDirect Seal sealing strip. This sealing strip is designed to provide maximum sound insulation and is available in several widths and thicknesses, making it possible to customize the seal to the specific needs of the door.

SilentDirect Seal has a strong double-sided adhesive tape on the back, making installation easy and secure. Applying the strip along the door frame creates a tight seal that reduces sound transmission while helping to prevent draughts and energy loss.

The benefits of a well-sealed door
A properly installed sealing strip has several benefits. In addition to effectively blocking sound between rooms, it also improves energy efficiency by reducing drafts and heat loss. This makes it particularly useful in both residential and work environments where comfort and sound insulation are important factors.

By combining SilentDirect Seal with other soundproofing measures, such as sealing the door frame and threshold and installing sound-absorbing material on the door, noise levels can be significantly reduced.

Other effective methods for reducing noise from a door

Use a fabric room divider
A simple but effective way to dampen sound from a door is to place a fabric room divider in front of it. By installing a curtain rod above the doorway and hanging a thick fabric, sound waves can be absorbed and reflected less. For best results, the fabric should be heavy and have sound-absorbing properties.

Install a double door system
If possible, a double door solution can provide significantly improved sound insulation. An air gap between the two doors acts as a natural sound barrier that dampens sound waves before they reach the other room. To maximize the effect, the gap between the doors should be lined with sound-absorbing material, such as SilentDirect Egg, which effectively reduces sound reflections and reverberations in the air gap.

Replace the door with a solid model
If your existing door is hollow and does not provide sufficient sound insulation, replacing it with a solid model may be a long-term solution. Solid doors with a core of sound-insulating material reduce sound penetration significantly more than lightweight interior doors. A high-density sound-rated door can be a good investment for environments where sound insulation is a priority.

Reduce sound reflections with a carpet or thicker floor covering
Hard floors can amplify sound through reflection, causing sound to spread more throughout the room. Laying a thick carpet or using sound-absorbing flooring can reduce sound reflections. This is particularly effective if the sound is coming from the other side of the door and bouncing off hard surfaces.

Consider specialized soundproof doors
For the most demanding environments, a specialized soundproof door may be the optimal solution. These doors are designed with multi-layer materials that effectively block sound transmission. They often feature improved sealing systems that eliminate gaps and ensure a tight seal around the entire door.

Combine several methods for best results
To achieve maximum sound insulation, it may be beneficial to combine several of these measures. The most suitable method depends on the room's use, budget, and the specific noise levels to be reduced. A well-designed sound insulation solution can significantly improve acoustic comfort and create a quieter environment.

Did you know that..

Did you know that a door can act as a sound amplifier rather than a sound barrier? If a door is too thin, hollow, or poorly sealed, it can not only let sound through but also amplify it through resonance. By using solid door leaves, sound-insulating sealing strips, and automatic thresholds, you can effectively reduce sound leakage and create a more soundproof environment.

Products that are good for soundproofing a door, door frame, and threshold

SilentDirect Polaric dampingmat
SilentDirect Polaric is a heavy damping mat made from a butyl blend with a durable aluminum surface. It is designed to effectively reduce vibrations and sound transmission through door leaves. Applying SilentDirect Polaric to the inside of the door creates a more solid and sound-insulating barrier. The thicker the material is applied, the better the sound insulation. The product also works excellently in vehicles, where it can be mounted on door panels and ceilings to reduce road noise and vibrations.

SilentDirect MLV
SilentDirect MLV (Mass Loaded Vinyl) is a heavy, flexible sound insulation mat that blocks sound transmission through doors and walls. By installing MLV on the inside of the door or between double panels, you can create an effective sound-absorbing barrier. SilentDirect MLV is also popular in the automotive industry, where it is used to block engine and road noise in doors and floors. The product is easy to adapt and cut to size as needed.

SilentDirect Egg
SilentDirect Egg is an advanced sound absorber made from NBR rubber (nitrile rubber), a material known for its exceptional sound-absorbing properties. Its unique egg shape breaks up sound waves and reduces reverberation, making it ideal for optimizing acoustics in rooms where sound insulation is critical. By installing SilentDirect Egg on the inside of the door, you can effectively reduce sound transmission. The product is also used in vehicles, where it absorbs sound waves and reduces resonance in engine compartments and door panels. For best results, a thickness of at least 35 mm is recommended, but 50 mm gives even better results.

SilentDirect Neo
SilentDirect Neo is a flat version of SilentDirect Egg and is made from the same highly absorbent NBR rubber. It is particularly suitable for installations where a smooth surface is required, such as on door frames and door leaves where aesthetically discreet sound insulation is desired. SilentDirect Neo is also an excellent solution for vehicles, where it is used to dampen sound from floors, ceilings, and door panels. For high-frequency sounds and complex sound environments, SilentDirect Egg is recommended, but where a flat surface is needed, Neo is the best choice.

SilentDirect Seal
SilentDirect Seal is a flexible sealing strip made of nitrile rubber (NBR), available in several thicknesses and widths. It is ideal for eliminating sound leakage between doors and frames, preventing sound from escaping or entering. By using SilentDirect Seal, you can reduce sound transmission through gaps and improve the overall sound insulation of the door. The product is also used in the automotive industry to seal joints and reduce airborne noise in the passenger compartment.

SilentDirect Seal Door
SilentDirect Seal Door is a premium seal designed for doors up to 55 mm thick and is particularly suitable for doors without thresholds. It is ideal for interior doors, steel doors in warehouses, basements, and other spaces where soundproofing is crucial. By installing SilentDirect Seal Door, you can effectively reduce sound leakage through the door opening and create a more soundproof environment. The product is also ideal for vehicles, where it can be used to seal and improve sound insulation in vans and transport vehicles.