Class O Acoustic Foam Sheets: Complete UK Guide

Author : Michael Jones | Published On : 02 Sep 2026

Class O Acoustic Foam Sheets: A Practical Guide

Managing unwanted noise is important in homes, workplaces, studios, vehicles, and industrial environments. The right acoustic material can help control reflected sound, reduce echo, and create a more comfortable space.

Acoustic foam is often chosen because it is lightweight, flexible, and simple to adapt to different surfaces. However, not every foam sheet offers the same acoustic or fire performance. Therefore, selecting a material according to the actual application is essential.

When fire performance is also part of the specification, Class O acoustic foam sheets can be a useful option for suitable acoustic treatment projects. These sheets are designed to absorb sound while providing documented fire-related performance, making them relevant to specification-led applications.

What Are Class O Acoustic Foam Sheets?

Class O acoustic foam is generally an open-cell polyurethane foam designed to absorb sound energy. Its cellular structure allows sound waves to enter the material instead of being reflected completely from a hard surface.

The term “Class O” is also commonly used when people mean “Class 0.” In technical documentation, it is important to check whether the specification refers to Class 0 and to confirm the exact fire-testing information provided for the selected foam.

Unlike conventional soundproofing materials, acoustic foam is primarily used for sound absorption and acoustic treatment. It can help reduce reverberation and reflected noise, but it should not be considered a complete sound isolation system.

How Does Acoustic Foam Control Sound?

Sound travels through a room as waves. When these waves hit hard surfaces such as walls, ceilings, metal panels, or equipment enclosures, they can reflect back into the surrounding area.

This repeated reflection creates reverberation and echo. In some environments, it can make speech harder to understand and increase the perceived level of background noise.

Open-cell acoustic foam helps by allowing some of this sound energy to enter its structure. The energy is then dissipated through the movement and friction within the foam cells.

As a result, suitable acoustic foam can help improve the acoustic character of a space. The overall result depends on factors such as foam thickness, coverage, installation method, room size, and the frequencies that need to be controlled.

Why Fire Performance Matters

Acoustic materials are sometimes installed in commercial, industrial, or specialist environments where fire performance forms part of the project specification.

For this reason, it is not enough to choose foam simply because it is described as “fire retardant.” Different materials can have different classifications and test results.

The current All Foam technical information states Class 0 performance to BS 476 Parts 6 and 7, along with Class 1 surface spread of flame to BS 476 Part 7 and additional UL94 classifications. The precise requirements should always be compared with the technical data for the product being specified. 

Choosing the Right Foam Thickness

Thickness has a major influence on how acoustic foam performs. A thin sheet may be suitable where space is limited or where basic reflection control is required.

Thicker foam generally provides greater material depth for sound absorption. Therefore, a 25mm or 50mm sheet may be considered when a project requires more substantial acoustic treatment than a very thin sheet can provide.

The correct choice should not be based on thickness alone. The required acoustic performance, available installation space, surface area, fire specification, and application should all be considered together.

Current Class 0 sheets supplied by All Foam are available in 6mm, 12mm, 25mm, and 50mm thicknesses, allowing different projects to be matched with an appropriate material depth. 

Where Can Class O Acoustic Foam Be Used?

Industrial Acoustic Treatment

Industrial machinery can create continuous background noise and unwanted reflections. Acoustic foam may be incorporated into suitable enclosures or surrounding structures to help absorb reflected sound.

It can therefore be useful in selected machinery, plant, engineering, and equipment applications where acoustic control is required.

HVAC and Ductwork

Air movement through ventilation systems can generate unwanted noise. Acoustic materials may be used within suitable ducting and ventilation applications to help manage sound transmission and reflections.

However, the material must be compatible with the airflow, temperature, fire requirements, and installation environment.

Studios and Recording Areas

Recording spaces require careful control of reflected sound. Acoustic foam can be used as part of a wider acoustic treatment strategy to reduce unwanted reflections and improve the listening environment.

Placement is particularly important. Covering every surface with foam is not automatically the best approach. A balanced treatment plan should consider the room's dimensions, surfaces, equipment, and intended use.

Vehicles and Equipment

The flexibility of polyurethane foam makes it practical for some automotive and equipment applications. It can be cut or shaped to fit around selected components and confined spaces.

Before installation, however, the operating temperature and other environmental conditions should be checked against the product specification.

Why Choose a Quality Foam Sheet?

A reliable acoustic material should offer more than a basic description on a product page. Technical information helps users determine whether the foam is appropriate for their particular project.

All Foam provides Class 0 acoustic foam sheets with documented product information and different thickness options. The company has more than 40 years of foam supply and conversion experience and supplies foam products for acoustic and other specialist applications across the UK. 

This type of information is particularly useful for commercial and technical projects where material selection needs to be based on documented specifications rather than appearance alone.
Visit for more:https://www.allfoam.co.uk

Class O Foam vs Soundproofing Materials

It is important to understand the difference between acoustic absorption and soundproofing.

Acoustic foam primarily helps control sound inside a space by absorbing reflected sound. Soundproofing, on the other hand, focuses on reducing the transmission of sound from one area to another.

A soundproof construction may require mass, isolation, decoupling, sealing, and other building materials. Acoustic foam can form part of an acoustic solution, but it should not be expected to stop all sound passing through a wall, floor, ceiling, or enclosure. 

 

How to Select the Right Acoustic Foam

Start by identifying the main problem. Is the goal to reduce echo, improve speech clarity, control machinery noise, or treat an enclosure?

Next, consider the available installation depth. A 6mm sheet and a 50mm sheet will occupy very different amounts of space and may be appropriate for different applications.

Fire performance should then be checked against the project specification. If a particular British Standard or classification is required, review the relevant technical data sheet rather than relying on a general product description.

Finally, consider how the foam will be installed. The current All Foam Class 0 sheet is supplied as an unbacked flat sheet, meaning the fixing method needs to be selected separately according to the installation. 

Frequently Asked Questions

Is Class O acoustic foam the same as Class 0 acoustic foam?

The letter “O” is commonly used when people search for this product, but the technical classification may be written as Class 0, using the number zero. Always check the exact wording and supporting technical documentation for the product.

Does acoustic foam completely soundproof a room?

No. Acoustic foam is mainly designed to absorb reflected sound and control reverberation. It can improve the acoustic environment, but complete sound isolation normally requires a broader construction using suitable mass, isolation, and sealing methods.

What thickness of acoustic foam should I choose?

There is no single thickness that suits every application. Available space, required acoustic treatment, installation method, and the frequencies being addressed should all be considered. Where the project specification allows it, comparing different thicknesses can help identify the most suitable option.

Conclusion

Class O acoustic foam sheets can provide a practical combination of sound absorption and documented fire performance for suitable applications. Their open-cell construction makes them useful for controlling reflected sound, while their flexible sheet format allows them to be adapted to different environments.

The most important step is to choose the material according to the actual application. By checking thickness, acoustic requirements, fire classification, installation conditions, and technical documentation, we can select an acoustic foam solution that is appropriate for the project rather than relying on a generic description.