22nd May 2024 -

When it comes to soundproofing your home or office, one of the most effective materials to install is soundproof plasterboard. This specialised drywall offers superior sound insulation, helping to reduce noise transmission between specific areas.

However, it is a challenge to understand the various sound ratings used to evaluate plasterboard soundproofing materials. Below, we outline these sound ratings, exploring the key factors that determine acoustic performance. 

What are the performance metrics of soundproofing plasterboard?

Several ratings metrics are used to measure and quantify acoustic performance. They offer valuable information about the material's ability to reduce airborne sound transmission, impact noise and overall sound insulation. Understanding these metrics is important for selecting the right sound insulation board product. 

Sound Transmission Class (STC)

STC measures the ability to reduce airborne sound transmission. It is particularly useful when evaluating the performance of sound insulation plasterboard in preventing noise from travelling between adjacent rooms or spaces. The higher the STC rating, the better the material is at blocking sound.

They are determined through tests that measure the sound transmission loss across a range of frequencies from 125 hertz (Hz) to 4000Hz. These frequencies cover the most common sounds, such as speech, music and television. A higher STC rating indicates better sound insulation performance. 

For example, an STC rating of 50 decibels (dB) is considered good for residential applications. However, a rate of 60 dB or higher is recommended for environments like recording studios or home theatres.

Impact Insulation Class (IIC)

While STC focuses on airborne sound transmission, the IIC measures the ability to prevent impact-generated noise from travelling through the structure. This rating is particularly important when considering soundproofing for floors. It evaluates how well the material can block impact sounds from footsteps, dropped objects or furniture movement.

Higher IIC ratings indicate better impact on sound insulation performance. An IIC rating of 50 dB or higher is acceptable for residential applications. A rating of 60 dB or above is generally recommended for louder environments.

Weighted Sound Reduction Index (Rw)

The Rw is another rating system used to evaluate the airborne sound insulation performance of materials including soundproof plasterboards. Like the STC rating, it measures the ability to reduce sound transmission across a range of frequencies. However, it follows a slightly different calculation method.

The Rw rating is calculated from a series of tests that measure the sound transmission loss across a wider range of frequencies, from 100Hz to 3150Hz. Higher Rw values indicate better sound insulation performance. Ratings of 50 dB or higher are generally considered good for residential applications. Whereas ratings of 60 dB or above are recommended for spaces with louder sounds. 

Weighted Normalised Impact Sound Pressure Level (Ln,w)

Ln,w is a metric used to assess the impact of sound insulation performance of ceiling and floor systems. It measures the sound pressure level in the receiving room, normalised for the amount of impact energy applied and the room's absorption area. Lower Ln,w values indicate better impact sound insulation. 

Sound deadening vs damping vs dampening

Various terms are used to describe different mechanisms of sound control. Understanding the distinctions will help with implementing plasterboard soundproof solutions. 

1. Sound damping

This refers to a material's ability to dissipate sound energy into heat, reducing vibration transmission and sound radiation. Effective sound damping in acoustic board systems improves the STC and Rw ratings by limiting airborne sound transmission. This can be achieved through the material itself or by using additional damping compounds. 

2. Sound dampening

Sound dampening means reducing sound energy through the absorption of vibrations. For soundproof plasterboard, effective dampening is achieved within the material itself or by adding dampening layers like viscoelastic compounds. Proper dampening boosts the IIC and Ln,w ratings by mitigating impact sound transmission.

3. Sound deadening

It converts sound energy into thermal energy within porous or fibrous materials. Soundproof plasterboard is often used alongside sound-absorbing materials like mineral wool insulation or acoustic panel materials. Effective sound deadening improves the overall acoustic performance by reducing sound reflections and reverberation. This creates a more controlled acoustic environment.

Is soundproof plasterboard thickness a factor?

The thickness of soundproof plasterboard can influence its sound insulation performance and ratings. Generally, thick panels perform better for airborne sound insulation because of their increased mass which helps block sound energy.

However, for impact sound insulation (IIC and Lnw ratings), the thickness may have less influence. This is compared to other factors like resilient channels, damping compounds or floating floor systems.

While thicker plasterboard often improves performance, the relationship is not always that simple. Other material properties and resonance frequencies also play a role. Manufacturers provide data on expected ratings for different thicknesses.

The overall system design, including installation quality and additional insulation, significantly impacts acoustic performance regardless of plasterboard thickness.

Does soundproof plasterboard meet UK Building Regulations?

Approved Document E (Resistance to the passage of sound) is the reference for acoustic performance requirements in the UK Building Regulations. It outlines the minimum standards for sound insulation in various types of buildings. 

Residential dwellings

With new dwellings and conversions, the building regulations outline minimum sound insulation requirements based on Rw and Ln,w. These requirements vary depending on the type of partition and floor or ceiling assembly.

  • Separating walls and floors between dwellings: Minimum Rw of 45 dB for airborne sound insulation, and maximum Ln,w of 62 dB for impact sound insulation.
  • Internal walls and floors within a dwelling: Minimum Rw of 40 dB for airborne sound insulation. 

Schools and educational buildings

For schools and educational buildings, the regulations impose stricter requirements to ensure an optimal learning environment. The minimum sound insulation performance for separating walls and floors is an Rw of 50 dB and a maximum Lnw of 60 dB for impact sound insulation.

Offices and commercial buildings

The acoustic performance requirements for offices and commercial buildings vary depending on the specific use. Generally, the regulations recommend a minimum Rw of 50 dB for separating wall and floor spaces, and a maximum Lnw of 62 dB for impact sound insulation.

How to perform a soundproofing test

To ensure that noise insulation plasterboard sheet installation meets the requirements, it is essential to conduct proper testing and measurements. The following steps outline the process for performing a soundproofing test. 

1 - Setup and equipment

  • Identify the separating wall or floor and ceiling structure to be tested. 
  • Set up the sound source room and the receiving room on either side.
  • Use a sound level metre or noise measurement system that meets the requirements of British Standard (BS) EN 61672-1:2013
  • Employ a loudspeaker or sound source capable of generating pink noise (rainfall; rustling leaves) within the required frequency range.
  • Utilise a tapping machine for measuring impact sound insulation.

2 - Testing

  • Measure the background noise levels in both the source and receiving rooms. This ensures they are sufficiently low for accurate testing.
  • Generate pink noise in the source room at various frequencies within the specified range (typically 100 Hz to 3150 Hz for airborne sound insulation tests).
  • Measure the sound pressure levels in the receiving room for each frequency band.
  • Calculate the sound reduction index (R) for each frequency band. To do this, use the difference between the source and receiving room sound pressure levels.
  • If testing for impact sound insulation, use a tapping machine in the source room and measure the sound pressure levels in the receiving room.

3 - Data analysis

  • Calculate the weighted Rw or the Ln,w based on the measured data. Follow the procedures outlined in BS EN ISO 717-1:2020 and BS EN ISO 717-2:2020.
  • Compare the calculated Rw or Ln,w values to the minimum requirements detailed in the regulations. 

4 - Considerations

  • Ensure that the test area is representative of the actual construction. This includes service penetrations, flanking paths or other potential sound transmission routes.
  • Follow proper test procedures and guidelines, such as those outlined in ISO 16283-1:2014 for field measurements of airborne and impact sound insulation.
  • Consider factors that may influence the test results such as background noise levels. 
  • If results do not meet the required performance levels, identify and fix potential issues. Be sure to implement the necessary measures before retesting.

What is the future of acoustic insulation plasterboard?

Soundproofing is continuously evolving, driven by the demand for better solutions and meeting stringent building standards. The future of soundproof plasterboard materials is expected to bring about significant developments. Below, we outline 5 key predictions for the future of soundproof plasterboard.

1. Improved acoustic performance

Manufacturers are always exploring new material compositions and techniques to enhance the sound insulation capabilities of soundproof plasterboard. This includes the incorporation of advanced damping compounds and innovative core materials. These improvements could lead to better STC and IIC ratings for effective noise control. 

2. Lightweight and sustainable options

As sustainability becomes increasingly important in construction, manufacturers look to develop lightweight and eco-friendly soundproof plasterboard options. These could include the use of recycled or renewable materials. Also, improved manufacturing processes could reduce carbon footprint without compromising acoustic performance.

3. Smart acoustics and adaptive systems

The integration of smart technology and adaptive systems could revolutionise the way soundproof plasterboard operates. For example, acoustic boards for walls or acoustic plasterboard ceiling panels could actively adjust their acoustic properties based on real-time noise conditions or user preferences.

4. Potential impact on building regulations

With the possibility of new soundproof plasterboard technologies offering improved acoustic performance and enhanced capabilities, building regulations will likely have to adapt. Minimum sound insulation requirements may be revised, particularly for sensitive applications such as residential dwellings, schools and healthcare facilities. 

Top-notch soundproof plasterboard for all projects

We supply a comprehensive range of soundproof plasterboard solutions for your needs. Our products from brands like British Gypsum and Knauf are made to provide exceptional noise control and sound insulation. Whether you are looking to reduce noise transmission or boost privacy, our soundproof plasterboards deliver superior performance.

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