The Free Closed Cell Foam Cut to size service lets you choose AFP30 or AFP45, select the thickness and enter the finished rectangular length and width you need. The right thickness depends on what the foam must do, not simply on the overall size of the piece.
A thin layer can suit separation, lining or spacing where depth is limited. A deeper piece provides more material through its thickness, but thicker is not automatically better for every job. Grade, load, available space, compression and the way the foam is supported all matter.
This guide explains how to approach the current 3mm to 100mm range without turning thickness into a one-size-fits-all recommendation.
Quick answer
Choose thickness from the available space and the job the foam needs to perform. All Foam supplies AFP30 and AFP45 in 3mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 40mm, 50mm and 100mm. Compare thickness together with grade because AFP45 is denser and resists compression more strongly than AFP30.
Start with the space available
Before choosing a thickness, measure how much depth the finished foam can occupy.
If a case lid must close over an item, the foam thickness cannot be considered separately from the item height and the internal case depth. If a pad sits between two components, the available gap may set the maximum thickness before material performance is even considered.
For a liner, check whether adding foam will reduce the usable internal dimensions too far. A 25mm layer on two opposing sides removes 50mm from the clear space between them.
This is why the first question should be practical: how much room is available for the foam after every other component is in place?
Thin closed cell foam from 3mm to 10mm
The thinnest options are useful where the requirement is primarily for a compact layer rather than a deep protective block.
Current online thicknesses in this range are:
- 3mm
- 5mm
- 10mm
These depths can be considered for thin liners, separation layers, anti-rattle pads, spacing and other applications where there is limited room for material.
Do not assume that a thin sheet provides the same cushioning effect as a deeper foam section. A 3mm pad has very little depth available for compression compared with a 25mm or 50mm piece.
Where the application involves meaningful impact or load, consider the complete construction rather than choosing a thin layer simply because it fits neatly.
Mid-range thicknesses from 15mm to 30mm
The current range includes:
- 15mm
- 20mm
- 25mm
- 30mm
These sizes provide more material depth while remaining practical for many flat pads, case liners, protective separators and industrial components.
A mid-range thickness often gives more scope for compression than 3mm to 10mm material, but the correct depth still depends on the item and load.
For example, a 25mm sheet does not automatically provide the right protection for every product. A small delicate component and a heavy industrial part can place very different demands on the foam even if the available space is identical.
Use thickness as one part of the specification, not as a universal protection rating.
Deeper closed cell foam from 40mm to 100mm
The deeper options are:
- 40mm
- 50mm
- 100mm
These thicknesses provide substantially more material depth and can suit applications where a deeper support, protective block, spacer or insulation layer is required.
A deeper piece also occupies more space and can increase the amount of material around the item. Check clearances carefully before ordering.
At 100mm, the foam is 10cm thick. That is a substantial section, so confirm that the finished dimensions and the surrounding structure genuinely allow for it.
If the project needs several layers rather than one deep piece, the bonding or mechanical retention method becomes part of the finished design. Do not assume that separate sheets will behave as one solid block unless they are converted appropriately for the application.
AFP30 and AFP45 do not behave the same at the same thickness
Thickness alone cannot describe how the finished piece will respond under load.
AFP30 has a nominal density of 30 kg/m³ and the current technical specification lists compression at 25% deflection as 62 kPa.
AFP45 has a nominal density of 45 kg/m³ and compression at 25% deflection of 100 kPa.
That means two pieces can both be 25mm thick but still provide different resistance under compression because the foam grades are different.
AFP30 is the lighter rigid cross-linked polyethylene option. AFP45 is the denser grade for applications needing greater load-bearing performance and rigidity.
The AFP30 vs AFP45 closed cell foam guide explains this grade choice separately from thickness.
Do not use density as a substitute for thickness
Density and thickness answer different questions.
Density describes the amount of material within a given volume. Thickness describes the physical depth of the foam piece.
Choosing AFP45 instead of AFP30 does not make a 5mm piece behave as though it were a 25mm piece. Equally, increasing AFP30 from 5mm to 25mm does not turn it into AFP45.
Both decisions need to be made deliberately.
A useful order specification therefore includes both:
Grade: AFP30 or AFP45
Thickness: 3mm to 100mm from the available range
Then add the finished length and width.
Think about compression space
When foam is used beneath a load or between surfaces, it needs space to compress if compression is part of the job.
If the material is already tightly trapped with no available movement, adding more thickness can create a different result from a pad that has room to deflect.
Similarly, a protective pad that is too thin may compress through its available depth more quickly than intended.
The correct design depends on the load, contact area, foam grade and surrounding structure. For critical industrial protection, validate the complete assembly rather than relying on thickness alone.
Case liners need a total depth calculation
If closed cell foam is being used inside a case, add the thickness of every layer.
For example, a 20mm base plus a 20mm lid pad uses 40mm of the internal case depth before the product is included. Side liners reduce the internal width and length as well.
Measure the case internally, then subtract the planned foam layers from the usable space.
This is particularly important with rigid AFP30 and AFP45 because the foam is not intended to collapse freely like very soft open-cell cushioning.
For reusable case applications, the closed cell foam flight case guide covers layout and material choice in more detail.
Gaskets, seals and spacers need the complete specification
Closed cell polyethylene can be used for suitable gaskets, spacers and sealing components, but thickness should not be chosen from gap size alone.
A sealing application can depend on compression, surface condition, fixing method, temperature, chemicals and required service life.
AFP30 and AFP45 are not universal substitutes for dedicated rubber or specialist sealing products.
If the project has a defined sealing specification, use the closed cell foam gaskets and seals guide and confirm the exact material requirements before ordering.
Insulation applications need more than thickness
A thicker foam layer may provide more physical separation, but All Foam does not publish an R-value for AFP30 or AFP45 on the product page.
Do not convert thickness directly into an invented thermal performance figure.
Where insulation is the main purpose, check the complete system, fire requirements, installation method and any project-specific thermal specification. The closed cell polyethylene foam insulation guide explains these limits.
Thickness is part of an insulation build-up, but it is not enough by itself to prove the performance of the finished assembly.
Water resistance does not decide thickness
AFP30 and AFP45 are supplied as waterproof, non-absorbent closed cell polyethylene grades. AFP45 additionally has a specified maximum water absorption of 1% by volume, while AFP30 is WRAS approved for cold-water use.
Those properties do not mean a particular thickness is required simply because the material may get wet.
Choose thickness for the physical job. Then separately check whether the material properties suit the environment.
A thin waterproof sheet remains thin. A thick waterproof sheet remains thick. Water behaviour and mechanical depth are separate decisions.
Measure before ordering cut to size
Once the thickness has been chosen, measure the finished rectangular length and width.
The online cut-to-size service uses the current standard parent sheets:
- 100cm × 100cm
- 200cm × 100cm
A cut that fits the smaller parent sheet is charged at that sheet price. A larger cut that fits within 200cm × 100cm uses the larger parent sheet. The cut itself has no separate charge.
The measurement guide for closed cell foam cut to size explains how rotation, maximum width and repeated pieces work.
A simple thickness checklist
Before adding the cut-to-size piece to your basket, check:
- the maximum depth available in the finished assembly
- whether the foam needs to compress under load
- whether the chosen grade is AFP30 or AFP45
- whether the foam is a liner, pad, separator, spacer or support component
- whether surrounding clearances change when the foam is added
- whether the application has technical, fire, sealing or regulatory requirements beyond ordinary sheet supply
- the exact finished length and width
- the quantity of identical pieces required
This gives a more reliable order than selecting thickness from appearance alone.
Choose thickness and grade together
The most useful way to buy closed cell foam sheets is to treat grade, thickness and finished size as one specification.
Choose AFP30 or AFP45 for the required material behaviour, select the thickness that fits the application, then enter the finished rectangular dimensions in the free cut-to-size section. This keeps the physical dimensions and the foam performance decision separate, while making the finished order clear.
