Plasterboard, also known as Drywall, is one of the most commonly used materials for soundproofing because of how effective it is and also because of its really low cost.
In this article, I will go over what plasterboard is, if it’s actually good for soundproofing, what the difference between regular plasterboard and soundproof plasterboard is, and which ones you should get to soundproof your home.
So, without any further ado, let’s get started!
What is Plasterboard?
Plasterboard, also called drywall, wallboard, sheet rock, to name a few, is a panel made out of gypsum (a soft sulfate mineral composed of calcium sulfate dihydrate) and generally mixed with some sort of fiber (glass wool, paper, or a combination of both) that is typically used in the construction of interior walls and ceilings.
Depending on the type of additives used within these sheets of plasterboard, or drywall, they can be fire and mildew resistant, or not absorb water.
Is Plasterboard, or drywall, good for Soundproofing?
Drywall is one of the most-used materials when it comes to soundproofing because of its effectiveness as well as low cost and ease of installation.
To soundproof, the most effective materials are the ones that block sound not absorb it (acoustic foam, for example, is a sound-absorbing material and doesn’t soundproof) and plasterboard fits that description perfectly.
In addition to this, plasterboard that has glass wool fibers in it is even better at reducing noise transmission because those fibers help absorb some of that sound energy further.
What is the difference between regular Plasterboard and Soundproof Plasterboard?
Regular drywall, or plasterboard, is made out of gypsum and has paper or glass fibers in it that help absorb sound, but there are other more expensive alternatives out there that come with a viscoelastic polymer between the two sheets of gypsum that acts like a rubber compound capable of absorbing vibrations, and therefore, more sound.
Important note: While this type of drywall might be slightly more effective at lowering noise transmission, it’s only worth it if the entire wall or ceiling is covered with it, since only using a couple of these panels in conjunction with lower-quality ones will completely negate the effect, and this ends up making it a much more expensive choice.
How is Soundproofing Performance measured? (STC Rating)
STC, or Sound transmission class, is the rating used in the US to describe how well a building partition can attenuate sound, such as interior partitions, ceilings, floors, doors, windows, etc.
In most other countries, the Sound Reduction index is used (SRI).
The STC rating reflects the decibel reduction of noise that a partition can provide, where a higher number, or rating, equals better results, or overall attenuation.
Here’s a table showing what each STC rating represents:
|STC||What can be heard|
|25||Normal speech can be understood|
|30||Loud speech can be understood|
|35||Loud speech audible but not intelligible|
|40||Loud speech audible as a murmur|
|45||Loud speech heard but not audible|
|50||Loud sounds faintly heard|
|60+||Good soundproofing; most sounds do not disturb neighboring residents.|
There are multiple factors that go into calculating the STC rating, such as the acoustic medium, mass, sound absorption, and more, of the materials, but I won’t go into too much detail about this since it doesn’t pertain to the article itself.
SCT Rating of Drywall/Plasterboard
A typical interior wall with ½” of drywall on either side will have an STC (sound transmission class) rating of 34 on its own, which means that it reduces the level of noise by 34dB.
This is considering that there are no additional insulation materials being used, such as Rockwool, Fiberglass, Green Glue, etc., and which can increase the STC rating dramatically when added.
As a reference, putting up two sheets of drywall on either side, not just one, and applying green glue between the sheets will give you an STC rating of about 56, which means that noise will be reduced by 56dB.
Generally speaking, drywall is one of the most efficient soundproofing methods since it can simply be installed on existing walls, ceilings, and floors, effectively lowering the amount of noise that is allowed to get through without being too costly.
Best Drywall, or Plasterboard, for Soundproofing
The two types of drywall or plasterboard I recommend are type C and type X.
Type X drywall has special core additives that allow it to be used in fire-rated designs, it has a fire resistance of up to 2 hours, and usually comes in 5/8” thickness, whereas Type C drywall is known as the more durable version of Type X plus there are more glass fibers in this product as well as more vermiculite components, giving it a fire resistance of 2-4 hours and making it better for sound insulation as well.
The Brands I’d recommend taking a look at are:
- CertainTeed Silent FX Quick Cut
- National Gypsum
QuietRock has always been the best-performing drywall on the market, but it’s also the most expensive one of the options available.
Let’s take a quick look at what each company has to offer:
QuietRock has a variety of products to choose from and these are considered to be the best ones out there (with a higher price tag, of course). Here are the best gypsum panels (drywall or Plasterboard) that they offer:
- EZ-SNAP: The EZ-SNAP panels deliver outstanding STC ratings with no paper or metal in the center of the panel, and they easily snap, making them simple to use and install, plus they have a fire rating of 1 hour.
- QuietRock 510: This is a 1/2″ cost-effective sound damping gypsum panel that is ideal for installation in residential homes (ideal when installing multiple layers since it’s ½”).
- QuietRock 530: This is a high-performance sound damping gypsum panel with added shear and impact resistance.
- QuietRock 545: This is the best overall multi-layer gypsum panel engineered to provide maximum sound attenuation across a broad frequency range (also the most expensive one).
- SilentFX Drywall: This noise-reducing drywall features a viscoelastic polymer between two specially formulated dense gypsum cores significantly improves sound attenuation and is ideal for systems requiring high STC performance.
- Type X Drywall: This is fire-resistant drywall is an interior gypsum board consisting of a solid set, fire-resistive, Type X gypsum core enclosed in ivory-colored face paper and a strong liner back paper that is also very effective at lowering sound transmission.
National Gypsum Drywall
- Gold Bond SoundBreak XP Wall and Ceiling Boards: Superior sound damping, cost-efficient material that finishes easily and decorates in the same manner as standard gypsum board.
A More Affordable Alternative
While all of these products may be great at doing what they’re supposed to, they can be multiple times more expensive than regular drywall which, on its own, is already an excellent sound insulator.
If you’re on a budget, then I’d recommend installing more than one layer of regular drywall (make sure the layer that goes on top of the other one is staggered so that it covers the seams) since this will provide excellent results at a very affordable price.
Always make sure to apply a healthy amount of Green Glue between the layers of drywall to further increase sound absorption.
Flame Spread Index
While this article focuses mainly on sound insulation, I think that it’s extremely important to address if plasterboard can be considered a fire hazard or not, which is determined by the flame spread index.
The flame spread index is determined by the distance that a flame travels along a test substrate in a specific timeframe to determine its propensity to burn and how rapidly it can spread flames.
It’s divided into these 3 classes:
|Class||Flame Spread Index|
- Class A fire ratings indicate a flame spread rating between zero and 25. Materials that fall into Class A or Class 1 include; brick, gypsum wallboard, and fiber cement exterior materials. These materials do not burn well and are very unlikely to contribute fuel to a fire.
- With a Class B or Class 2 fire rating, the flame spread rating would fall between 26 and 75. This rating is typical for slower-burning whole wood materials, such as planks that are in the same form as they were when they were cut from the tree.
- A Class C or Class 3 fire rating has a flame spread rating between 76 and 200, which incorporates building materials like plywood, fiberboard, and hardboard siding panels, as well as any of the faster burning whole woods.
What is the best Plasterboard for soundproofing then?
Despite being the most expensive one on this list, QuietRock 545 is the best overall multi-layer gypsum panel when maximum sound attenuation across a broad frequency range is required.
However, I don’t think that most people should be running out to get this type of drywall since it’s much more affordable to just get regular drywall and install two layers of it with Green Glue between those sheets of drywall, resulting in a similar or even better noise reduction at a fraction of the price.
I would only recommend the high-end stuff, such as the QuietRock 545 for high-end applications, such as soundproofing music studios, for example.
How does Drywall actually reduce sound transfer?
Like all soundproofing materials, drywall blocks outside noise and also absorbs a lot of the energy of the soundwaves.
Here are the main reasons that it’s so effective at it:
Drywall adds mass, plain and simple. The more mass the harder it is for sound to get through. For sound to move through a wall, it actually needs to make it vibrate slightly and the more mass the wall has, the harder it will be for sound to achieve this.
Even though drywall itself isn’t designed to absorb soundwaves, like acoustic panels do, for example, it generally does have glass fibers in it which aid with this, and if you get the SilentFX ones that have the viscoelastic polymer in them, then sound absorption will be even higher.
This is one of the main ways of soundproofing since decoupling helps prevent vibrations from transmitting from one structure to the next, and if you install the drywall using a decoupling method to separate them from the wall, then noise transmission will be much lower.
Other ways of reducing sound transmission
The simplest way is to install drywall and to put some sound-absorbing material between it and the wall/ceiling.
If you’re closing up an interior wall with drywall, make sure to fill the interior of that wall with Rockwool, Fiberglass, cellulose, etc., in order to have those sound-absorbing materials further reduce noise.
The best solution would be to install the QuietRock 545 panels since those are more effective than all of the other options, at a much higher price, of course.
However, I would recommend getting cheap drywall and installing two layers of it instead of just one and applying Green Glue between the sheets to further reduce vibration and noise transmission.
Last Updated on May 16, 2022 by Facundo