Choosing between flat and convoluted acoustic foam sheets starts with the space, the available treatment depth and the fire information required for the project. Both profiles are intended to absorb reflected sound within a room or enclosure. The surface shape affects appearance, fitting and the range of thicknesses available, but neither profile should be treated as automatic proof of better performance.
This guide explains the practical difference between flat and convoluted acoustic foam without treating either profile as automatically better. All Foam currently sells the flat Class 0 acoustic foam sheet only. The former standard flat acoustic sheet and convoluted or egg-crate acoustic foam are retained here as educational comparisons for customers researching or replacing older installations; they are not current All Foam products.
If the main question is whether acoustic foam will stop noise passing between rooms, read Does Acoustic Foam Soundproof a Room?. It separates internal acoustic treatment from building sound isolation.
What acoustic foam is designed to do
Acoustic foam is used to reduce reflections within an enclosed space. Reflected sound can create reverberation, flutter echo and a harsh or confused listening environment. Adding suitable acoustic treatment can help make speech, music and equipment noise feel more controlled inside that space.
Common uses listed within the All Foam range include recording and rehearsal spaces, media rooms, machinery enclosures, wall treatment and general sound control projects. The right product depends on the purpose of the space and the specification that applies to it.
Acoustic foam should not be confused with complete sound isolation. It mainly treats sound after it reaches the foam inside the room or enclosure. It does not, by itself, create a complete barrier that stops sound travelling through walls, floors, ceilings, doors or gaps.
Reducing sound transmission normally requires a wider construction approach. That can involve mass, isolation, sealing and attention to the complete building or enclosure. Acoustic foam may form one useful part of a project, but it should not be sold or selected as a complete soundproofing system on its own.
The main difference between flat and convoluted foam
Flat acoustic foam has an even face and can create a clean, simple finish across a wall, panel or enclosure. The current All Foam purchasable acoustic sheet is the flat Class 0 grade in 25mm and 50mm. Historical standard flat acoustic foam was offered in a wider range of thicknesses, which is why older All Foam guides may show additional depths.
Convoluted acoustic foam has a raised profile, often described as an egg-crate surface. The visible peaks and recesses create a textured appearance. Exact peak height, valley depth and overall thickness vary by manufacturer, so use the specification of the product being compared rather than assuming all profiled sheets are built the same way.
The profile is therefore only one part of the choice. A customer may prefer flat foam because the finish is quieter visually, because a particular thickness is needed or because the treatment has to sit within a limited depth. Another project may suit convoluted foam because the textured appearance is acceptable and the fixed profile fits the intended enclosure or treatment area.
Do not choose from appearance alone. Fire information, sheet dimensions, backing and exact product grade can matter more than whether the face is flat or profiled.
Standard flat acoustic foam
Standard charcoal flat acoustic foam is a general acoustic treatment material used to reduce reverberation, reflections and flutter echo. All Foam does not currently supply its former standard flat acoustic foam product; the current purchasable acoustic sheet range is the Class 0 Acoustic Foam.
Historical product information described the former standard sheet as fire retardant and listed three sheet sizes: 76cm by 100cm, 230cm by 100cm and 230cm by 200cm. Those sizes are not part of the current All Foam acoustic range.
The former standard flat sheet had the broadest historical thickness choice, from one quarter of an inch (6.3mm) through to four inches (101.6mm), with intermediate options of one half inch, one inch, one and a half inches, two inches and three inches. These are historical specifications, not current ordering options.
That range can be useful where the available treatment depth is already known. A shallow panel, machinery enclosure or fitted wall system may not accept a deep sheet. Another project may have enough room for a thicker layer. The flat product gives more freedom to compare these depths without changing to another surface profile.
The former standard flat acoustic sheet was supplied unbacked. The current Class 0 flat sheet is also supplied unbacked, so the fixing method can be selected separately for the substrate and project.
If you are replacing a former standard flat sheet, use its historical dimensions only to identify the old installation. For a new All Foam purchase, compare the current Class 0 flat sheet and confirm that its technical specification suits the project.
Standard convoluted acoustic foam
Convoluted acoustic foam is generally a profiled open-cell treatment material with raised peaks and recesses. It is commonly considered where a visibly textured surface is acceptable. All Foam does not currently list a standard convoluted acoustic foam sheet for online purchase.
If you are comparing a profiled acoustic sheet from an older installation or another specification, check its exact material grade, fire information, overall profile depth, sheet size and fixing method. Those details should not be inferred from the egg-crate appearance alone.
A profiled sheet can still be relevant to an acoustic design, but its actual performance and suitability depend on the product specification, coverage, placement, room or enclosure and the sound problem being addressed.
The convoluted product should not automatically be described as better than flat acoustic foam. The actual result depends on the product specification, coverage, placement, room or enclosure and the sound problem being addressed. The profile can be a useful practical and visual difference, but it does not remove the need to plan the complete treatment.
If you are replacing an existing standard convoluted acoustic lining, identify the original product specification and available depth before selecting a current alternative.
Class 0 flat acoustic foam
The Class 0 Acoustic Foam Sheet is a flat cellular acoustic foam listed as Class 0 accredited. It is intended to help reduce reflections and improve sound control. The current product information describes it as fire retardant and suitable for studios, enclosures and sound treatment areas.
The Class 0 flat sheet is supplied in two sizes. These are 100cm by 100cm and 200cm by 100cm. Available thicknesses are 25mm and 50mm.
The flat Class 0 sheet is supplied unbacked. This lets the fixing method be matched to the substrate and maintenance plan.
The Class 0 flat option can suit a project that specifically requires the stated Class 0 product and where a smooth face is preferred. The current 25mm and 50mm thicknesses allow a customer to choose between a shallower and deeper option within this product grade.
Class 0 should not be treated as a general description for all acoustic foam. It applies to the products that are clearly identified and documented as Class 0 within the range. A standard fire retardant acoustic sheet should not be represented as Class 0 simply because it looks similar or is intended for a related use.
For regulated, public or commercial settings, read the supporting document and confirm the exact requirement before ordering. The foam data sheets provide the available technical documents for the current range.
Class 0 convoluted acoustic foam
A convoluted Class 0 acoustic foam would combine a profiled surface with a stated fire classification, but the profile alone does not establish Class 0 performance. All Foam currently lists the flat AFPCLS0 Class 0 acoustic foam sheet rather than a convoluted Class 0 sheet.
If a specification specifically names a profiled Class 0 material, obtain the technical data for that exact product. Do not apply the AFPCLS0 flat-sheet data to a different construction simply because both products are described as Class 0.
The practical selection point is the same as with standard acoustic foam: surface shape, treatment depth and installation format are separate from the material grade and documented fire performance.
Standard fire retardant or Class 0
Historical All Foam information used two different levels of product wording: the former standard flat acoustic sheet was described as fire retardant, while the current AFPCLS0 product is identified separately as Class 0 acoustic foam. The former standard sheet is no longer supplied.
These descriptions should remain separate. Fire retardant is not a substitute phrase for Class 0, and Class 0 should not be added to every acoustic foam product.
Start by reading the project requirement exactly as it has been supplied. A domestic media room may have a different approval process from a commercial enclosure, public space or contract installation. If a customer, contractor or site document names a particular test or classification, compare that wording with the relevant product data sheet.
The fire retardant foam guide explains why application, documentation and the finished construction should be checked together. It also explains why colour, texture and thickness do not prove fire performance.
When the specification is unclear, contact All Foam before purchase and provide the intended use, location, required document, dimensions and quantity. This is more reliable than asking for a general fireproof foam, because the correct answer depends on the stated requirement and product grade.
How thickness affects the choice
Thickness is one of the clearest differences when comparing flat and convoluted formats.
The former standard flat acoustic foam ranged from 6.3mm to 101.6mm. The current Class 0 flat foam is available in 25mm and 50mm. For any convoluted foam being compared elsewhere, check the stated maximum profile height and valley depth because those dimensions differ from a flat sheet measurement.
This means flat foam offers the widest choice where the project has a strict depth limit or needs a particular build. Convoluted foam offers a simpler fixed profile where that depth is suitable.
Select thickness after choosing the correct product grade. A thicker standard sheet does not become Class 0. A shallow Class 0 sheet does not become the right choice for every acoustic problem simply because it carries that classification.
Measure the space available for the foam itself and allow for any panel, enclosure, frame, covering or backing used in the finished construction. A sheet that is technically suitable but too deep for the available space will not produce a practical installation.
The foam sheet thickness guide explains how thickness should be considered alongside material, use and fit across the wider foam range.
Sheet size and coverage planning
Before ordering, measure the exact area that will receive treatment. Record the width and height of each separate surface. Do not rely on the overall room dimensions if only selected wall areas, panels or enclosure faces will be covered.
The former standard acoustic products were offered in three sheet sizes, including the larger 230cm by 200cm format. The current Class 0 product uses 100cm by 100cm and 200cm by 100cm formats.
Choose a sheet layout that suits the measured area and the way the foam will be fitted. Larger sheets can cover more area with fewer joins, while smaller sheets may be easier to position within divided panels or compact enclosures. The best arrangement depends on the surface dimensions, access and the appearance required.
Calculate the number of sheets from the usable sheet dimensions rather than the product image. Allow for any trimming, shaped sections or areas that cannot be covered with a complete rectangle. Where several surfaces are involved, calculate each one separately before combining the totals.
It is also useful to mark the proposed treatment areas before ordering. This helps confirm whether the planned coverage is balanced, whether doors or equipment need clearance and whether the chosen sheet size will create awkward waste.
Fixing flat acoustic foam
The current Class 0 flat sheet is supplied unbacked. The former standard flat sheet was also supplied unbacked, but it is no longer a purchasable All Foam product. Check the live Class 0 product page for current sizes, thicknesses and prices.
Check whether the foam may need to be removed, replaced or repositioned later. Also check whether a separate board or panel system forms part of the design. In some projects, the foam is fitted to a removable panel rather than directly to the final wall or enclosure.
Where fire documentation is important, confirm the supplied product format and the complete installation requirement. The fixing method does not determine the fire performance of the foam itself.
Flat foam for a cleaner appearance
A flat surface can be easier to integrate into a space where the acoustic treatment is visible. The former standard flat charcoal sheet provided a simple finish, while the current Class 0 flat sheet provides the stated Class 0 option in a smooth format.
Flat foam may be preferred for framed panels, neat wall sections, internal enclosure linings or spaces where the treatment should not dominate the visual design. Its even face can also make it easier to plan straight joins and consistent panel shapes.
Historically, the standard flat sheet provided a broader thickness choice. The current Class 0 range is intentionally simpler at 25mm and 50mm, so selection should be based on the live product specification rather than an old thickness list.
This does not mean flat foam is always the correct choice. A project that calls for a profiled sheet, a specific fixed depth or a textured treatment area may suit convoluted foam better. Appearance should support the practical specification rather than replace it.
Convoluted foam for a profiled treatment surface
Convoluted foam creates a visibly textured treatment surface. It may suit recording spaces, machinery enclosures, media rooms and other applications where the egg crate profile is acceptable.
Profiled products vary by manufacturer and grade, so the maximum peak height and valley depth should be checked from the exact specification. Do not assume a standard or Class 0 profile has one universal depth.
The raised surface should not be used as the only reason for purchase. Compare the exact fire information, sheet size, fixing method and project use. A profiled packaging foam, for example, is not automatically an acoustic product. The material grade and product description matter as much as the visible shape.
The same caution applies when replacing existing foam. An old profiled sheet may look similar to a current acoustic product but have a different material, fire status or intended use. Identify the requirement rather than matching only the appearance.
Studios and recording spaces
Recording and rehearsal spaces are common uses for acoustic treatment. In these settings, the goal is normally to manage reflections within the room rather than stop all sound leaving it.
Begin by identifying the actual problem. A room may have excessive reverberation, clear flutter echo between opposing surfaces or strong reflections around a listening or recording position. The treatment layout should respond to the room rather than cover surfaces without a plan.
The choice between flat and convoluted foam can then be based on available depth, appearance, product grade and the panel arrangement. Flat foam provides more thickness choices. Convoluted foam provides a fixed textured profile.
A small room does not automatically require the thinnest product, and a larger room does not automatically require the deepest. The correct treatment depends on the room, surfaces and intended use. Where detailed acoustic performance is critical, professional acoustic assessment may be needed.
Media rooms and listening spaces
Media rooms were among the uses listed for the former standard acoustic product and can also be relevant to the current Class 0 product where its specification suits the project. Reflections from hard walls and other surfaces can affect clarity inside the room. Acoustic foam can be used as part of an internal treatment plan.
A flat product may suit a cleaner interior design or framed panel arrangement. A convoluted product may suit a space where the treatment is intentionally visible. The chosen fire information should match the setting, and the sheet dimensions should fit the planned treatment zones.
Do not expect foam alone to stop television, cinema or music sound passing into adjacent rooms. That is a sound transmission issue and requires attention to the wider structure, doors, gaps and construction.
Use acoustic foam for the problem it is designed to address. Clear expectations help avoid spending money on treatment that cannot solve the main issue.
Machinery and equipment enclosures
Machinery enclosures are listed as a suitable use across the acoustic range. In this setting, selection needs to consider more than surface shape.
For specification-led industrial work, our Class 0 acoustic foam for machinery enclosures guide covers airflow, temperature, access, contamination and fixing choices in more detail.
Measure the internal space, moving parts, ventilation areas, access panels and any surfaces that must remain clear. Confirm that the selected thickness does not interfere with equipment or maintenance access. Check the required fire information and installation method for the environment.
A flat sheet may be easier to fit where depth varies or where panels need a smooth lining. If an existing enclosure specifies a profiled sheet, confirm its exact construction, clearance and technical data before sourcing a replacement.
Acoustic foam should not obstruct ventilation or be placed where the project conditions exceed the material specification. Where heat, oil, moisture, chemicals or unusual operating conditions are involved, obtain technical confirmation before ordering.
Common selection mistakes
One common mistake is calling acoustic treatment soundproofing. Foam can reduce reflected sound inside a room or enclosure, but complete isolation needs a wider construction approach.
Another mistake is assuming convoluted foam is always better because it looks more technical. The profile is only one feature. Flat foam may provide the thickness, fire information or finish that better suits the project.
A third mistake is treating every charcoal or egg crate sheet as the same product. Packaging foam and acoustic foam can have similar visible profiles while being designed for different purposes. Always use the product name, description and data sheet.
A fourth mistake is assuming all fire retardant acoustic foam is Class 0. The website deliberately separates standard fire retardant products from the Class 0 range.
A fifth mistake is ordering by room size without measuring the actual treatment surfaces. Doors, equipment, panels, windows and uncovered areas all affect the required quantity.
A final mistake is selecting thickness before product grade. Choose the correct acoustic and fire specification first, then select from the thicknesses available for that exact product.
A practical comparison
The former standard flat acoustic foam may still appear in older specifications because it was a charcoal fire-retardant sheet with three sheet sizes and a broad thickness range from 6.3mm to 101.6mm. All Foam does not currently supply it.
If you are comparing standard convoluted acoustic foam, check its actual fire status, maximum profile depth, sheet size and installation requirements. All Foam does not currently supply either the former standard flat sheet or a standard convoluted acoustic sheet.
Choose the current Class 0 flat acoustic foam when its stated Class 0 product information suits the project, a smooth face is preferred and either 25mm or 50mm fits the available depth. Then plan a suitable fixing method for the installation.
If a specification specifically requires a convoluted Class 0 product, obtain the exact technical data for that profiled material. All Foam currently supplies the flat AFPCLS0 sheet for Class 0 acoustic applications.
If the requirement still is not clear, compare the product cards and technical documents before purchase. The exact use, dimensions and fire wording should lead the choice.
Final checks before ordering
Confirm whether the project is treating reflections inside a space or trying to reduce sound transmission through a structure. Acoustic foam is intended for the first task.
Confirm the exact fire and acoustic requirement. If an older specification names standard fire-retardant acoustic foam, note that All Foam no longer supplies its former standard sheet; the current purchasable acoustic sheet is the Class 0 product.
Measure the treatment surfaces, available depth and any required clearances. Select a sheet size and thickness that fit the actual layout.
Decide whether a flat or convoluted face suits the appearance and treatment design. Then confirm the backing arrangement for the exact product.
Read the relevant data sheet and keep the product information with the project records where documentation may be needed later.
For current products, review the complete foam sheet range or contact the All Foam team with the intended use, dimensions, required fire information and quantity.
