Soundproofing walls, windows and doors for better acoustics
The acoustic performance of a home or office space can largely be attributed to soundproofing walls, windows and doors.
Walls are common barriers separating one room from another, while windows and doors provide a means of entering and exiting a room while also serving as sound diffusers.
Unfortunately, sound transmission and absorption issues can arise when spaces lack adequate soundproofing.
Using soundproofing to reduce noise can be as easy as adding some insulation or it can be something far more complex.
It all depends on the amount of noise you are dealing with and the size of the space you are trying to soundproof.
If you want to get the most out of your soundproofing investment, whether professionally done or DIY, then here are some tips to help you achieve optimal acoustical performance from your soundproofing efforts.
The importance of a sound control strategy
Sound control strategies must be considered from day one of a new construction project as they can provide significant cost savings during design and construction.
The first step in developing a sound control strategy is to consider if an existing structure needs sound control or if sound control should be considered during new construction.
Sound control is required to prevent noise transmission between conditioned spaces so that occupants of each space can enjoy their experience free from unwanted sounds.
If adequate sound insulation between areas cannot be achieved through minimal means (e.g., interior drywall or cellulose insulation), then heavier-duty products such as steel studs with wallboard installed on both sides will be necessary.
Techniques for reducing unwanted noise
Soundproofing walls or sound-isolating windows and doors can help you reduce unwanted noise in any space.
There are many ways to choose which route is best for you—for example, if your main concern is preventing outside noise from entering your living space, sound-blocking windows may be more suitable than floor panels.
For more information on how to proceed, talk with a local professional contractor—who can answer any questions you have and help point you in the right direction.
These are some things to do to reduce unwanted noise in any space:
- Eliminate the noise. Consider whether undesired noises such as mechanical equipment operation, HVAC, elevators, and others can be removed.
- Use absorbing materials. Thicker and denser wall materials, for example, can be utilized to absorb sound, whereas hard, non-porous surfaces reflect and stimulate sound.
- Soundproof the area. To prevent sound from being transferred from one space to another, use sound barriers in the building layout.
- Consider noise-masking or noise-absorbing designs. Apartments, for example, contain comparable purpose rooms nearby in multi-family construction. Quiet spaces, such as bedrooms, are adjacent to louder rooms, such as kitchens.
These are not mutually exclusive — many of the best solutions will employ multiple strategies at once.
That said, some materials work better than others depending on how they're used, so keep in mind that mass is your friend when soundproofing walls, windows and doors.
Things to keep in mind when soundproofing walls, windows and doors
Walls and floors are generally more straightforward than windows when it comes to soundproofing.
For example, you can usually add a layer of drywall to create an airtight seal between rooms.
Window insulation kits are another option that's easy to install.
However, when soundproofing windows, you might have trouble making them effectively soundproof because of their ability to swing open or be removed entirely.
Also, make sure to soundproof all possible paths for "flanking noise."
Flanking noise will not only pass through floors and walls but will find ways through poorly-sealed joints, penetrations, open ceiling spaces, and other wall cavities, too.
The Sound Reduction Index or Rw is a system that measures the level of sound insulation that walls, floors, windows and doors provide.
The higher the Rw figure, the better the sound isolation that is provided which means you are a step closer to soundproofing walls, windows and doors.
So, an Rw=62 dB can be reduced by closing the gaps around the perimeter, like so:
- If there is a 0.01mm gap, then Rw = 50 dB
- If there is a 2mm gap left, then Rw = 25 dB
There are some things that impact your soundproofing strategy
The mass of the material.
While soundproofing materials can help reduce noise, they aren't the only factor.
The mass of the materials used to build a room or even just a wall can also have a significant impact.
The heavier the material, such as stone, concrete, brick and thick plasterboards, the more sound is blocked.
Framing studs in walls, made with wood or steel, don't block sound very well.
This is why rooms with concrete walls are quieter than those with wooden walls.
A room built inside a basement with cinder block walls will be quieter than the one built at a street level against wooden exterior walls.
The overall thickness of materials.
Thickness plays a big role in how much sound is absorbed by a particular material.
Generally speaking, the thicker it is, the more effectively it absorbs sound.
How thick your wall or glass is, will vary depending on what you're using to soundproof it; plasterboard and standard drywall (2x4s) are 2 to 5 cm thick, for example.
That thickness makes them about as effective at absorbing sound as thin carpeting—the heaviest of acoustic fabrics—is at reflecting sounds back into a room.
On top of that, some products feature different types of materials or layers with varying densities to absorb sound.
Variations in thickness within a composite.
You can often get better soundproofing walls by using multiple layers of thinner materials rather than a single layer of thick material.
This allows you to create more layers of air gaps that act as natural sound insulators and it’s also a little bit cheaper, too.
This is especially true for windows and doors.
You can improve the Rw rating of an insulated glass unit by putting together glasses with different thicknesses.
Eliminating leaks of air and, therefore, sound
In order to prevent sound from passing through cracks and crevices in your building's construction (door or window frames, electrical outlets, etc.), you should use a sealant to fix them.
As mentioned above, to prevent sound flanking, each window/door/wall junction along the perimeter must be adequately sealed with a flexible acoustic sealant.
A cornice can also provide an acoustic barrier to minimize flanking, as long as it is installed correctly and an airtight seal is achieved and maintained.
But keep in mind to also protect the drywall edges you have installed around your door and window opening.
The most effective way to achieve maximum sound reduction is by combining the methods described above.
Soundproofing walls, windows and doors can be an essential part of improving the acoustics within any area or space, or it can actually make them worse.
That is why before you embark on any soundproofing project, you must obtain professional advice—you need to understand the issues and potential solutions.
One of the most common soundproofing solutions is using much-maligned acoustic foam.
However, research shows that many smaller homes do not benefit from the use of foam sound-blocking panels; instead, they may see improvement that is more significant in their acoustics through simple soundproofing measures.
This means that material type and installation methods are more important than people think.