Cavity walls have been a boon and a bane for many, depending on their usage. They are a special type of wall that consists of two separate walls and has a space between them.
The walls are called the skin of the cavity wall, wherein the air pocket inside the walls is called the cavity.
The outer skin of the cavity wall is generally made of brick and is located in the exterior of the structure, whereas the inner skin can be made of brick, concrete block, clay, reinforced concrete, etc. Both skins are connected using bonding blocks and metal ties, increasing the strength of the cavity wall.
Cavity walls have their pros and cons. Cavity walls are alternatives to normal walls in many places. They offer a higher level of insulation from the heat coming from the outside, and this is due to the air pocket present in between the walls.
It also provides insulation against moisture content from rain. Moreover, cavity walls cost less than normal walls, are economical and cheap, and provide many functionalities. They are lighter than solid walls and hence exert less pressure on the foundation of your structure. Most cavity walls have to weep holes in them that help takes down moisture content.
However, like all good things, cavity walls have their drawbacks—the most important of them all being the level of soundproofing.
Cavity walls can provide soundproofing to an extent, but it isn’t without limitations. Cavity walls have less mass than normal walls, and this provides less attenuation to the sound passing through the wall than a normal wall of the same size.
A thing to add here is that cavity walls are perfect for soundproof structural noise or impact sounds. Because the air pocket is present in between and the exclusivity of the two walls, no vibration reaches the inner skin of the wall cavity.
9 Ways to Soundproof Cavity Walls
In this article, we will be seeing some of the best methods for cavity wall soundproofing. The list has been specially curated with cost-effectiveness and cost reduction as major criteria.
Check for Holes
The biggest concern for any walls that need soundproofing is the cavities, gaps, and cracks they might have. If a cavity hall has cracks in it, there is not enough material on the other side to keep the sound away, and hence these gaps can contribute very much to the sound you are hearing inside your home.
You must check for holes and seal them before moving to advanced soundproofing solutions. There are many methods for sealing gaps on walls. You can either use weather-stripping tape or even a caulk seal to seal the gap shut. We recommend using a caulking gun to seal the gaps as you can maintain precision and get a better finish using it. Once it dries, you can paint over it, and you won’t even recognize the seal.
Cavity Wall Insulation
If you are sure there are no gaps in the wall, you can consider cavity wall insulation. It is the process of injecting soundproofing materials into the existing cavities to block incoming and outgoing sounds effectively. But, it is to be noted that such procedures are done by trained professionals and are not recommended to try at home.
It is perfect for cavity walls with unfilled air pockets. Still, the cost of cavity wall insulation varies according to the cavity, the material used, and the labor cost in your area. The most commonly used filler material for cavity wall insulation is mineral fiber wool, polystyrene granules, or polyurethane foam.
Soundproof Paint
Soundproofing paint is a perfect choice if the level of soundproofing you desire is minimal. They are an economical and aesthetically pleasing method of soundproofing any walls, let alone cavity walls. What makes soundproof paint different from normal paint is the presence of latex.
The latex in the paint acts as a soundproofing material, and once the paint dries, you can feel the texture of latex on the painted surface.
Keep in mind, soundproof paints are often used as complementary solutions to go with other dedicated solutions.
This is not a standalone fix for your noise problems and can only block normal sounds and medium-pitched noise, and they have little to no effect on frequencies of extreme ends on both sides.
There are a limited number of options in soundproof paint when compared to the spectrum of choice presented to us in the normal paint section.
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Soundproof Wallpaper
An alternative to soundproofing paint is soundproof wallpaper. Available in many different patterns, shapes, and sizes, soundproof wallpapers are aesthetically pleasing and have utility.
They may not seem like it, but they have built-in special materials layers dedicated to soundproofing walls.
These layers don’t block out sound permanently but can attenuate it little by little. They are best suited for blocking sounds of mid-range frequencies like soundproof paints.
An advantage of soundproof wallpaper is that you can easily install, maintain and remove the wallpaper without much effort, and it is a cost-effective solution.
Mass Loaded Vinyl
One of the best ways to soundproof a weak insulator is by adding MLV to it. Mass Loaded Vinyl is a dedicated soundproofing instrument that is light, flexible, and versatile.
It can cover any type and shape of vertical walls and be used between or on top of existing construction materials. This is particularly useful in cavity walls as you can fill the cavity with MLVs.
They are washable and can even be painted over, and if you don’t like to ruin the aesthetics of your home, you can buy them in transparent form.
Soundproof Foam
Soundproof foam or acoustic foam is perfect for you if you face disturbances due to airborne noise. These can easily dissipate a wide frequency range of noise and help you dampen the sound in the room and subsequently reduce the echo in the room.
These are perfect for professional environments such as recording studios and homes. This foam can be inserted inside the wall cavity with the help of a professional, thereby maintaining the aesthetics of the house.
They are made of polymers such as polyurethane and need little to no maintenance.
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Soundproof Curtains
Often used for windows, soundproof curtains can also be used for doors and walls. They are very good soundproofing solutions and allow users to reverse their choice if not needed. Soundproof curtains are like regular curtains but made of special soundproofing materials. They can have an STC (Sound transmission class) rating above 26 and lie closely clinging to the surface to soundproof.
Soundproofing curtains are heavier than normal curtains and cost more than normal curtains. They can block sounds and even reduce the echo of your room by attenuating the sound and transforming it into heat energy. A thing to note while buying soundproofing curtains is the size of the curtains. You can’t soundproof only a section of the cavity wall and expect it to work. One has to cover the entire surface and more to expect good results. This allows sound to come from every direction and facilitates cavity wall soundproofing.
Soundproof Blanket
It can seem weird at first, but soundproofing blankets are versatile and widely accepted solutions to soundproof cavity walls. The main theory behind most soundproofing solutions is the addition of mass that can effectively absorb the sound, and soundproof blankets or acoustic blankets are amazing sound absorbers.
The best thing about soundproof blankets is that it is easy to install and maintain. Soundproofing blankets increase the total mass of your wall and dampen the sound, and they can also reduce the total echo produced in a room. These are low-cost, high-efficiency soundproofing solutions and can increase the aesthetics of your home if done right.
Bookshelf Near the Wall
If you’re looking for economical solutions to soundproof your cavity wall, then take out the old books from the attic and arrange them neatly on or near the cavity wall.
You can create or install a bookshelf and stuff it up with books, and this will effectively increase the mass of the materials blocking the incoming and outgoing sounds. Be sure that the wall has enough strength to hold the weight of the books if you decide to wall-mount the bookshelf.
This is not limited to bookshelves, and you can rearrange your furniture and other decorations of high mass and direct them towards the direction of your wall cavity.
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Final Thoughts
In this article, we have seen what a cavity wall is and how it is different from normal walls. Cavity walls, as we have seen, have their pros and cons. It is the due diligence of the consumer to find where to install cavity walls. Cavity walls are better at blocking impact noise, but they have less mass than normal walls and may need soundproofing.
We have also discussed 9 different cavity wall soundproofing solutions that you can implement to soundproof a wall cavity. The solutions mentioned above are cost-effective and can provide maximum soundproofing to your walls. It is to be noted that it is advised to use combinations of the solutions mentioned above for maximum efficiency.