How To Soundproof A Brick Wall: 6 Effective Methods That Work


how to soundproof a brick wall

As a fellow row house dweller, I know how disturbing and creepy it is to hear your neighboring unit out loud through walls. Houses that are old and haven’t got renovated for a longer period of time are most notorious for noise transmission.

To restore the lost tranquility and combat the noise problems, the obvious solution would be to soundproof the wall. However, for an inexperienced, it can turn out to be a rather complicated task to put into practice. But the good news is:

To soundproof a brick wall, you don’t have to be an acoustic consultant either. If you possess the basic knowledge of how sound transmits and the fundamental understanding of the available soundproofing techniques, you are at the ideal place to start fixing your walls.

Some of the potential methods we will use to soundproof a brick wall are plugging sound leaks, installing extra layers of drywall, using mass loaded vinyl, insulation, acoustic panels for absorption, etc.

How Does Sound Pass Through a Wall?

Do you know sound transmission between units is one of the major problems that concern the condo dwellers? Although brick is a solid and dense material specifically used for acoustic purposes, have you ever wondered how is it possible that sound penetrates it?

When sound waves collide or hit a wall, a certain amount of the energy and momentum carried by the pressure waves gets reflected back into the room that creates an echo, and a part of it gets absorbed by the object. However, some of the sound waves – the remainder – transmit through the wall. And the way it travels is by the vibration of the air molecules that transfer their oscillations to the atoms/molecules of the wall, causing it to vibrate and pass the sound to the other side.

Lastly, it picks up by the air molecules present on the other side of the wall and ends up hitting your eardrums. But, it’s not the original sound vibration that you hear, but a reconstructed signal.

Sound is nothing but the vibration of molecules in the air, and the way it propagates makes it possible to travel through adjoining walls.

However, the amount of sound that gets transmitted through the brick walls is minimal due to the mass and density of the material. According to a study, a single layer brick wall is capable of giving about a 45dB sound reduction that means the sound that reaches your ear should be in a fainted state.

So if you are hearing somewhat clear voices or conversation of the neighbor residing in the next unit to you, probably that means there is something not right with your wall. Pay attention to it; there might contain cracks, air passages, or maybe bad mortar where the sound is coming from because it’s unlikely for sound to travel – where it is audible for one to understand – through a solid wall, which has no cracks whatsoever.

Unless there is a good enough opening in a wall for the air to escape, sound waves couldn’t get through it clearer. If you hear the noise out loud on the other side of a wall, that clearly means it has either weaknesses in the structure or poorly-sealed gaps or devoid of isolation materials to dampen down the vibrations.

Needless to say, the sound prevention majorly depends on the thickness of a wall (noise barrier), but since here we are talking about brick walls that we know comes with reasonably good density, it implies the wall in your house needs some serious soundproofing fixes.

[Related Article: How Soundproof Is Drywall As A Material For Home Projects]

The Right Way to Approach Noise Problems In Home

For someone who hasn’t tried soundproofing before stands a chance to get overwhelmed with the varying solutions required to fix an acoustically poor wall. For the very reason, it’s crucial to do the preparation beforehand. It may sound a straightforward process as simple as implementing a set of points given, but when you are DIYing it, you run the risk of messing things up, and therefore you need to be deadset about your objectives and methods.

Finding where the Sound is Coming From

In general, to diagnose any problem, you first have to know its origin. As we know, sound waves seek out the path of least resistance to travel, making it increasingly difficult for anyone to pinpoint the leaks. However, your two ears can detect the sound’s origin.

You can do that by starting with shutting off all your home appliances or gadgets that make any sort of sounds so that you can track the noise coming out from another side. Take your time to inspect all openings and passageways so you don’t miss out on any air gaps. The weak points that are more susceptible to providing flanking routes for sound to travel between walls are the ventilation systems and ducting, columns or corner posts, steel structures, lintels, and structural supports.

If walls are not completely interconnected and have any spaces left between the perpendicular walls, sound can easily pass through it. You may require to pull off the trim to look for missing caulk, and if you don’t find any issue with it, that could mean the wall lacks mass or maybe proper insulation.

Understanding Building Structures & Common Problems

To determine why your building has a noise leak and how you can fix it using different acoustic solutions, you must first inspect its structure thoroughly. That simply means if you can hear your neighbor through the adjoining wall, get to know the building structure, its various layers, and fabrics used to build it. The primary reason to do this work is to figure out how sound is traveling from its source to the receiving point, and if you can get to the root, you can fix it with much efficacy.

In brick or masonry walls, small holes and gaps are a common problem that often causes noise issues. However, if you find the wall to be perfectly and tightly closed, then it might be the wall’s density or its structure that’s letting the sound in.

We have seen many homeowners wasting money on soundproofing walls by doing more than what they need to do, and that’s the only reason we advise you to don’t overlook this step. If you aren’t able to carry out this step on your own, you may take some professional help to make it easy for you to proceed.

[Related Article: Choosing The Best Wallpaper To Soundproof Your House Guide]

The 4 Elements of Soundproofing

For acoustic isolation, below are the soundproofing principles that deal with the prevention of sound leakage or sound ingress.

Depending on the severity of the noise problem, you can choose one or multiple approaches that you think favors your situation the most. Here our primary aim with these 4 given principles is to stop the vibrations, particularly from getting to your side of the wall.

Deflection

Deflection refers to the principle of blocking out and pushing back the sounds wave to the source it’s coming from. For an object to deflect the sound, it has to be dense in its consistency. High-pressure sound waves can easily penetrate a wall that lacks thickness. For a brick wall, you can stick drywall to it as a cost-effective method to increase the density. In the soundproofing methods section, we have covered it in great detail.

NOTE: Denser objects are good at preventing sound from getting through. However, density always comes with rigidity, and this is what makes the principle to work against you as a flanking pathway. Certain sound waves will still pass through the material, and as a result, whatever is attached to it will also experience that; in our case, it is a wall.

Absorption

This principle is particularly useful when you are dealing with wall cavities. If you got a wall that is hollow due to its structure or framing system, it tends to trap air inside that resonates and causes noise problems. You can understand it in this way – A wall that has a void which has left completely open, when it comes into contact with sound waves or acoustic energy, vibrates the air molecules in the cavity, just like a drum. And the air cavity works as a medium for the sound waves to travel from one side of the wall to the other.

To prevent these wall cavities from resonating or transferring the vibration further, we part fill them up with sound insulating materials such as fiberglass thermal insulation, cellulose, mineral wool, and recycled cotton. It allows the sound waves to enter and then slow down its energy, thus reducing the sound power and sound pressure that came from the initial source. Moreover, it offers a certain amount of absorption and possible thermal benefit.

The key point to keep in mind is that the insulating material should be really thick to achieve a higher level of sound insulation but keep the density low and do not compress it when try to part fill the dead spaces because this will massively increase the thickness of the entire assembly. That, consequently, will make it easy for some lower frequency sound waves to travel through the material.

By adding the sound-absorbing material to the right level of thickness into the build, you can potentially enhance the vibration reduction value of the wall that will further aid you in preventing any additional acoustic resonance or regeneration.

Dampening

Damping refers to a set of methods or tools that helps in reducing the acoustic vibration in a structure, wall, or system. We have seen many homeowners using the term damping and sound absorption interchangeably, which is wrong. It may look like both principles work the same way. However, it is not the case. Sound absorption is used to dissipate airborne sound waves, whereas damping eliminates the dynamic stresses associated with vibration in order to remove it.

By applying damping materials, we reduce the impact of vibration on a wall, and when the sound waves couldn’t carry its energy forward, it gets mitigated, thus causing no noise problems. The materials used for damping purposes are designed so that it takes sound vibrations in, creates friction in its molecules that, as a result, converts the acoustic energy into trace heat energy. Besides, incorporating appropriate sound damping measures adds to the wear or fatigue life of a wall.

To determine the level of damping provided by different materials, you have to rely on its damping coefficient. Technically, it measures the material’s capacity to bounce back or reflect the energy back to its source. Materials having lower damping coefficients produce a higher rate of bounce back of the acoustic vibration energy, whereas materials with a higher damping coefficient reduce vibrations or shock by shocking up its vibrational energy and turning it to less problematic heat energy.

Decoupling

The main idea behind the decoupling principle is to separate two sides of the structure by way of batten or resilient channel so that they can vibrate independently from each other. Wall decoupling is all about isolating one side of a wall to prevent the sound from passing through on the other side.

Sound vibration needs a really solid pathway to travel with much efficiency and momentum, but if we decouple the framing in our walls, much vibrations cannot go any further to the other side. And this is the whole point of separating both sides, and it’s certainly one of the most effective ways to soundproof your wall if you can hear whats’s going on to the other side.

Most standard walls are traditionally studded – single stud construction – which means both sides of a wall have a common stud they are connected to. In this case, when sound waves hit one side of the wall, the vibrations can travels to the other side with the help of the stud connecting both of them. The only solution to this problem is to go for a staggered-stud framing, which keeps the two sides of the wall from touching, thus preventing the vibrations from transmitting.

Without a doubt, decoupling improves the sound reduction performance of a wall, but sadly, it has a downside too. When we introduce a space between the materials, the air in the cavity created by decoupling acts results in resonance. While higher frequencies wouldn’t bother you much, lower frequency sound will easily transmit to the other side. But don’t worry, you can prevent it from happening, for that, you may require to increase sound isolation (dampening) or maybe some mass into the build.

[Related Article: Can You Soundproof A Cavity Wall?]

Best Ways to Soundproof a Brick Wall

how to soundproof a brick wall

Once you are aware of the basic soundproofing principles that are prominent to get the optimum results, it will be easy for you to choose the type of method you should use, depending on your wall’s requirement. In some cases, where you need only a few minor changes to make, it could be done using any particular method, but in certain conditions, you may require to employ one or a mixture of all the available options to get the best possible outcome.

This is why you have been advised in the initial section to get to know the problem and the situation of your wall because while deciding the right construction techniques and materials to soundproof it, the understanding of the building structure and fabrics is going to make a whole new difference.

Keep this in mind, regardless of the technique you choose to go with, the density of a wall is going to be the crucial factor. Also, you’ll certainly require some budget for the construction, so decide it before getting practical with the workarounds.

Method 1: Plug Sound Leaks

It makes sense to seal all the cracks, crevice, and openings in the wall first before you head over to any advanced method. Don’t leave any holes left open because the sound is like water, and it will find a way to get through; even the tiniest of a gap is enough for the sound waves to transmit.

You can use Green Glue Noiseproofing Sealant to fill the joints and penetrations and don’t forget to check around the outlet and switch boxes. Green Glue is not only the best in the business but also an affordable product that will solve most of your noise issues.

Method 2: Add Extra Acoustic Drywall

If you remember, out of four soundproofing principles that we have discussed earlier, one way to prevent the sound is to deflect it using materials with high density and mass. In that case, brick walls are already working in our favor, but for any reason, if they have started leaking noise, the obvious solution would be to strengthen its sound deflecting properties.

And to do that, in a pretty straightforward way, you will require to use acoustic drywalls. It helps in reducing sound transmission by adding mass and thickness to a wall that makes it hard enough for the vibrations to get through. Without a doubt, drywall is one of the most efficient products to add soundproofing to a wall, especially where it is not practical to reframe or use other structural methods.

But here we have a majorly debatable topic regarding drywall, which is essentially a dilemma choosing between standard drywall vs. sound-dampening drywall. While doing our research, we have found that soundproofing drywalls are inherently better than traditional drywall in terms of resisting sound transmission. On an estimation, acoustic drywall tends to add 18 dB of noise reduction over regular 5/8″ drywall that ranges up to 5 dB – 10 dB max.

You’ll find several mainstream brands in the market that deal with soundproofing drywall panels, but QuietRock is currently the best known of all. QuietRock and some other companies that produce acoustic drywall have claimed that a single layer of soundproofing drywall is as effective as eight layers of standard drywall.

Products specially designed and developed for noise proofing are certainly more resilient and less able to transmit sound waves. And this what makes them a costly choice, but if you are looking for a long-term fix to the noise nuisance, the investment will be worth it.

Green Glue Company 10730 Noiseproofing Compound, 12 Pack

A very reasonable approach would be to spread the Green Glue over the drywall panel and then screw the drywall into place. You have to keep in mind that using a metal screw will potentially reduce the acoustic insulation of the drywall. For that reason, it’s crucial to cover joints and nail holes using Green Glue drywall caulking, acoustic mud, and a tape system once the drywall compound has set.

Method 3: Mass-Loaded Vinyl (MLV)

MLV is an inexpensive yet effective way to soundproof your apartment’s acoustically poor wall. The product has been made especially for noise prevention. Mass loaded vinyl doesn’t only offers impressive sound-reducing abilities but is also relatively easy to stick on a wall. It improves the Sound Transmission Class (STC) ratings of the structure and helps mitigate the noise.

Mass loaded vinyl comes with a relatively high density, and this is what makes it one of the best in the league. It’s a non-toxic, flexible material that comes in 4-foot-wide rolls and can be easily stapled to drywall or hanged/glued to a plaster wall. For a greater impact on the reduction of sound transmission, use MLV between the layers of drywall.

To get the intended results, proper sealing is crucial, so make sure to caulk the perimeter once you are done hanging, sticking, or sandwiching it to your existing wall. You can buy Mass loaded vinyl from local stores or online.

Method 4: Apply Acoustic Panels on the brick wall

For homeowners looking for a quick fix, you can buy sound-absorbing panels for your room. These panels act as a sponge for the sound vibrations that soak it in before the sound reaches your ears.

It can also help improve the sound quality of your room. Acoustic panels come in various sizes and thicknesses, with dozens of colors and styles available to choose from. For home use, you can buy custom-printed fabrics that can also be used for home decor to enhance the room’s aesthetics.

Method 5: Insulation may work

If you want to perform the insulation technique for a wall, you will be needed professional help to determine how that could be done in your case. The method will vary based on how the wall was constructed, what type of framing structure, and assembly it has been installed to.

Certain types of brick walls don’t stand any chance of getting insulated after post-construction due to its type and fabrics used – unless you want to take the whole wall down and re-build a new over it. So if your wall falls into this category, don’t worry because you have other ways to get the task done.

Method 6: Decoupling (Need professional work)

We have already discussed decoupling in great detail, so we will not elaborate it further here. Rather we have listed some of the prominent ways in which decoupling can be done.

There are four ways decoupling can be done:

  • A room within a room
  • Double stud wall
  • Staggered stud wall
  • Sound isolation clip

Should You Care about STC Ratings?

NOTE: Don’t take STC ratings too seriously when specifying a soundproofing system, material, or product. STC ratings only register sounds that are over 125Hz, which means it doesn’t take low frequencies into account; therefore, it’s an incomplete measurement that we can’t rely on solely.

Sound transmission class or STC is an integer rating of how well a wall partition reduces airborne sound transmission. Almost all soundproofing products come with an STC rating by which we can determine the number decibels of sound reduction a product might provide at its prime. Higher STC numbers mean better sound-proofing.

You should at least try to achieve an STC rating of above 50, and you are more likely to reach this goal just by filling up and sealing all the voids and penetrations in the brick wall. And if you install 1 layer of 5/8″ drywall on each side of the wall with fiberglass insulation, accompanying stud of your choice, you will easily exceed the STC ratings of 60 or above.

[Related Article: 52 Soundproofing Materials and DIY Tips That Fit Any Budget]

Finishing Touch

A poorly sealed wall is always going to cause issues regardless of its deflection properties or sound-absorbing qualities. There are many quick fixes available in the market, such as hanging soundproofing blankets, curtains, and foam panels, but none of them will produce satisfactory results if you left your wall’s areas of weakness unfixed.

Pay attention to repairing crumbling mortar and penetration, plugging holes, and gaps for effectively noise proofing a brick wall.

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