Acoustic Plaster: The Definitive Guide

Written by Daniel
Last updated

If you’re looking for an acoustic treatment that can really make a difference, acoustic plaster may be the solution you’ve been searching for. Acoustic plaster is made of natural materials that absorb sound, making it an ideal choice for rooms where noise control is important. In this article, we’ll discuss the science of acoustic plaster, and we’ll take a look at some of its best applications. We’ll also give you some tips on how to install it yourself!

What is acoustic plaster?

Acoustic plaster is a type of plaster that contains fibres or aggregate to help absorb sound. Early plasters contained asbestos, but newer ones typically have a base layer consisting of absorptive substrate panels made from mineral wool or non-combustible inorganic blow-glass granulate. When soundproofing with plaster you want to finish the substrate panels by adding a first layer of plaster, and sometimes add a second for further soundproofing. Although pre-made acoustic panels are usually more popular, acoustic plaster gives a neater look and can be tweaked more easily if needed. The downside is that it takes more expertise to apply correctly. 

Properties of Acoustic Plaster

Acoustic plasters help to muffle sound and reduce echo within a space. The Noise Reduction Coefficient, which is used to measure the performance of acoustic materials, typically falls between 0.5 and 1 for these types of plasters. The Noise Reduction Coefficient (NRC) measures a material’s capacity to reflect or absorb sound. A result is always a number between 0 and 1, with 0 meaning the material perfectly reflects sound and 1 meaning it perfectly absorbs it. Acoustic plaster can help to improve the clarity of speech, music, and other sounds in a variety of desirable environments. Acoustic plasters are also LEED rated and fireproof; however, they can be more delicate since they can physically stress and humidity.

The best applications for acoustic plaster

While acoustic plaster provides an advantage, it is only effective if the person mixing and applying it has high levels of skill. To get the best sound absorption coefficients, you must follow the directions for proportion and recommended mixing time exactly. To achieve a flawless surface, start with an even ceiling. Next, fix the sound-absorbent substrate panels in place and fill any gaps before sanding them down so they’re level with the surface. After the plaster coats are applied, a smooth surface is achieved with layers. If you want a different texture for your acoustic platers, you must act quickly after it’s applied.

The different types of mounts for acoustic plasters not only affect its adhesive performance but also their acoustics. These mounting types include direct-to-substrate, suspended or direct-to-framing, or a plaster-only system that can be sprayed on the surface without extra support. Control joints are cracks in the plaster that need to be considered when buildings any type of construction project.

Acoustic plaster is used to construct rooms that need good sound quality, such as auditoriums and libraries. Some examples of proprietary types of acoustic plaster are Macoustic Plaster, Sabinite, Kalite, Wyodak, Old Newark and Spray-Flake. These superseded felts and quilts as a common preference of architects but were difficult to apply so they in turn were superseded by acoustic tiles.

How to apply acoustic plaster

Plastering is one of the final steps in finishing an interior or exterior wall. While applying plaster is a highly technical process that is usually best left to professionals, any homeowner can do it themselves provided they follow a few key guidelines. 

1. Choose the right type of plaster for your project. There are a variety of plasters on the market, so be sure to select one that is appropriate for your needs.

2. Prepare the surface you will be plastering. This step is crucial for ensuring a smooth, even finish.

3. Mix the plaster according to the manufacturer’s instructions.

4. Apply the plaster to the surface, using a trowel or other suitable tool.

5. Smooth out the plaster with a wet sponge or brush.

6. Allow the plaster to dry completely before painting or applying any other type of finish.

Acoustic Plaster v Acoustic Plasterboard

The main difference between acoustic plaster and acoustic plasterboard is the weight. Acoustic plasterboard is generally much lighter than acoustic plaster, making it easier to transport and install. Acoustic plasterboard is also less messy and doesn’t require as much time or expertise to apply. However, acoustic plaster provides better sound absorption than acoustic plasterboard.

When deciding whether to use acoustic plaster or acoustic plasterboard for your project, consider the following factors: – The weight of the material. If you need a lightweight option, go with acoustic plasterboard. – The ease of installation. If you want an easy-to-install option, go with acoustic plasterboard. – The level of sound absorption you need. If you need a material that provides better sound absorption, go with acoustic plaster.

The pros and cons of acoustic plaster

  • Pros: Acoustic plaster not only improves acoustics and speech intelligibility but also is suitable for a wide range of substrates such as walls and ceilings. By using this product, you will create a more pleasant working and living environment while also increasing productivity.
  • Cons: Using extra weight and depth can help reduce the number of sound waves being deflected, which is helpful for people who need to increase their acoustic calibration.


What is acoustic plaster?

Acoustic plaster is a type of plaster that is used to improve the acoustics of a room. It is generally made from a mix of gypsum, perlite, and vermiculite.

How does acoustic plaster work?

Acoustic plaster works by absorbing sound waves, which reduces the amount of noise in a room.

Where can I use acoustic plaster?

Acoustic plaster can be used on walls and ceilings. It is often used in rooms that require good sound quality.

Is plaster more soundproof than drywall?

Plaster is more soundproof than drywall because it is thicker and denser. Plaster also has a higher Sound Transmission Class (STC) rating, which means it absorbs more sound.

What are the disadvantages of acoustic plaster?

The main disadvantage of acoustic plaster is that it is heavier and more difficult to install than acoustic plasterboard. It is also more expensive.

How do I apply acoustic plaster?

Acoustic plaster can be applied with a trowel or other suitable tool. It is important to make sure the surface you are applying it to is clean and smooth. You should also make sure the plaster is mixed according to the manufacturer’s instructions.

Can I paint over acoustic plaster?

Yes, you can paint over acoustic plaster. However, it is important to allow the plaster to dry completely before painting.

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