Sound Dampening on a Budget: Key Strategies for Reducing Noise
Got a loud laundry room? Is the noise from the living room hampering your ability to work from the home office? Or maybe your neighbor is too loud and you have a shared wall. Learn how to economically dampen noise transmission and why sound migrates through building assemblies in the first place.
How Sound Travels Through Walls
The solutions laid out below are in order of importance based on cost and feasibility. It looks like this: air sealing, mass, absorption, cavity depth, specialty products, and decoupling. By addressing these factors, you can significantly reduce sound transmission from room to room.
Here’s a closer look at each:
Seal Air Gaps
Sound moves through air, even through the smallest openings. Think of it like this: you could have a thick concrete wall, but if there’s a small hole in it, you’d still be able to have a conversation with someone on the other side.
Solution: Seal any gaps around outlets, switches, windows, doors and wall edges with foam backer rods and sealants. Wrap fire putty around outlet boxes to air seal and increase their mass. For new construction, consider adding beads of caulk to the top and bottom plates and then embedding the drywall into the caulk to create a gasket. Also consider embedding the bottom plates of walls in a caulk or acoustic sealant.
Increase Mass
One of the most effective ways to block sound is by increasing the mass of your walls. Heavier materials are harder for sound waves to vibrate. Think of it this way: sound travels through vibration. The heavier the material, the more energy it takes to make it vibrate, so it’s more resistant to sound transmission.
Solution: Create a wall with two layers of 5/8” drywall on at least one side of the wall. You can also install thicker or solid-core doors. These options help create heavier barriers that are more resistant to sound vibration.
Add Absorption with Insulation
Insulating wall cavities can absorb sound waves and reduce their ability to pass through the wall. Fiberglass insulation helps dampen noise by absorbing sound waves as they travel through a wall cavity. When sound waves hit the insulation, the fibers within the material create friction, which converts the sound energy into heat, thereby reducing the noise. Additionally, the random arrangement of fibers and air pockets in the insulation disrupt the movement of sound waves, preventing them from traveling through the wall efficiently. This makes fiberglass effective at minimizing mid- and high-frequency sounds
Solution: Fiberglass or mineral wool insulation is great for absorbing sound. When the cavity resonates, it resonates inside a material designed to absorb vibrations. This constant disruption of the sound waves helps deaden noise.
Green Glue: Sandwiched between two layers of drywall, Green Glue shears and dissipates sound energy as it passes through, turning sound vibrations into heat. This dramatically improves the sound-blocking abilities of a standard wall without requiring complex construction methods. Green Glue—or its competitors—should be used whenever adding additional layers of drywall, as it offers an affordable yet highly effective solution for reducing sound transmission.
Deepen the Cavity
A deeper wall cavity reduces sound transmission by lowering the wall's resonant frequency. All materials, including walls, have a natural frequency at which they vibrate most efficiently. When sound waves match this frequency, the wall can resonate and amplify the sound. By increasing the depth of the wall cavity, the resonant frequency is lowered, making it more difficult for common sound frequencies to cause vibration and resonance, thereby reducing sound transmission.
Solution: For new construction, consider using 2x6 studs instead of 2x4s. For a retrofit, consider adding furring strips to the existing studs to create more wall depth.
Specialty Products for Sound Reduction
Below area additional means of deadening sound. These should usually only be considered in addition to the methods employed above.
Acoustic Panels: These can be added to walls or ceilings to absorb sound within a room, helping reduce echoes and reverberation. In the same vein, items like thick rugs and curtains also act as fantastic sound deadeners.
Asymmetrical Dual Pane Glass Windows: One pane is thicker than the other, which helps disrupt sound waves. The difference in thickness prevents the sound waves from traveling easily through both panes because different frequencies are absorbed or reflected differently by each pane.
Sound Dampening Insulation: While fiberglass insulation dramatically dampens noise, products like Rockwool’s Safe‘n’Sound insulation can dampen noise even further by virtue of its density.
Decoupling
Decoupling involves physically separating the two sides of a wall so that sound vibrations cannot easily pass through solid materials. Normally, in a single-stud wall, sound waves strike one side of the wall, cause it to vibrate, and those vibrations easily transfer through the shared studs to the other side. This is what allows sound to pass through walls, floors, or ceilings. Decoupling changes that by removing the solid bridge where vibrations can travel.
Solution: Create a double stud wall. In a double stud wall configuration, the drywall on one side of the wall is attached to one set of studs, while the drywall on the other side of the wall is attached to a different set of studs. The studs don't touch, creating an air gap between the two sides. This space allows sound waves to dissipate instead of being transmitted. The result is a dramatic reduction in sound transmission compared to traditional single-stud construction. This is a great option for new construction, particularly in the design phase.
What is STC?
The Sound Transmission Class (STC) rating measures how well a wall or partition blocks sound. The higher the STC, the better the sound reduction. Here's a general guide:
STC 40: Loud speech is audible but unclear.
STC 45: Speech is mostly inaudible.
STC 50-55: Normal conversations are inaudible, and elevated levels of noise (like shouting) are muted.
STC 60+: Nearly complete soundproofing, where most sounds, including loud music, are blocked.
For everyday purposes, an STC rating between 50 and 55 is excellent for shared walls. Click here to explore examples of common wall assemblies and their STC ratings. STC ratings aren’t a perfect science. Low frequencies from bass are very pervasive and will likely still be heard at higher STC assemblies; however, STC ratings still paint a picture for how one may fair in typical occupancy conditions.
Managing Expectations: Reducing Noise vs. Soundproofing
It’s important to understand that reducing sound and soundproofing are different goals. Economical solutions can help deaden noise, but full soundproofing is a far more complex and costly process. You can add more drywall, insulation, and Green Glue, but there are limits. Sound doesn’t just travel through walls—it moves through floors, ceilings, windows, doors, and even HVAC ducts.
When working on sound reduction, keep these expectations in mind. For example, sealing off a room completely from the rest of your house could disrupt your HVAC system. The air that goes into your room needs a way to return to the system. If you block air from flowing freely—say, by adding weather stripping to your office door—you could depressurize the remaining rooms, potentially causing other issues in your home, like increased energy usage or indoor humidity problems.
Conclusion: Finding the Balance Between Budget and Results
Reducing sound transmission in your home doesn’t have to be expensive, but it’s important to manage your expectations. Economical options like adding mass, deepening wall cavities, sealing air gaps, and adding insulation can make a big difference in reducing noise. However, remember that soundproofing is an entirely different beast.
If you’re looking for a more peaceful space, selecting one or more of these affordable techniques will help you achieve that. But keep in mind that it’s impossible to block all sound without major renovations.
