Aluminium foam is a porous metal, typically 70 – 90 % air, that gives architects a non-combustible, moisture-proof and recyclable panel for facades, ceilings, partitions and acoustic linings. Closed-cell foam brings stiffness, impact absorption and a distinctive metallic texture; open-cell foam brings sound absorption and airflow. This guide explains the types, the properties that matter on a building project and how to specify foam panels correctly.
Aluminium foam is aluminium or an aluminium alloy expanded into a cellular structure, like a metal sponge. A typical construction-grade foam weighs roughly a tenth to a third of solid aluminium, so a 20 mm foam panel can weigh less than a 3 mm aluminium sheet of the same area while being far stiffer in bending.
For construction, the attraction is the combination of properties rather than any single one. The material is metallic all the way through, so it does not burn, rot, absorb water, shed fibres or support mould. It can be cut, drilled and fixed with ordinary metalworking tools. It reflects light in a way no other cladding does, and it can be fully recycled with other aluminium scrap at the end of the building's life.
Those advantages come at a higher material cost than mineral wool, gypsum or aluminium composite panels, so foam is normally chosen where it does more than one job at once: a facade that is also an acoustic absorber, a ceiling that must be non-combustible and washable, or a feature wall that must survive impact in a public space.
Every aluminium foam belongs to one of two families. The difference is whether the pores connect to each other, and it decides almost everything about how the material behaves in a building.
| Property | Closed-cell foam | Open-cell foam |
|---|---|---|
| Pore structure | Sealed cells separated by thin aluminium walls | Interconnected pores, a continuous metal network |
| Typical density | about 0.25 – 0.85 g/cm³ | about 0.2 – 0.6 g/cm³ |
| Typical pore size | about 1 – 10 mm (often 3 – 8 mm) | about 0.5 – 5 mm, set by the process |
| Stiffness and strength | Higher for the same density | Lower; better protected behind a face |
| Sound absorption | Low as cast; good once cells are opened by rolling, drilling or slicing | Good without treatment |
| Air and water permeability | None; does not take up water | Allows air and liquid to flow through |
| Main building uses | Facades, cladding, sandwich cores, partitions, impact linings | Acoustic linings, ventilation grilles, heat exchange, filtration |
Closed-cell foam is usually made by the melt route: molten aluminium is thickened with fine ceramic or calcium particles so that bubbles stay stable, then foamed with a gas-releasing agent or with injected gas, solidified into large blocks and sliced into slabs. Open-cell foam is normally made by casting or infiltrating aluminium around a removable space-holder (for example salt granules) that is later dissolved out, which lets the maker control pore size closely.
A bold, open texture that reads well on facades from a distance. Good structural stiffness for the weight and, in open-cell form, high air permeability for vents and grilles. Weaker as an absorber at speech frequencies unless backed by an air gap.
The general-purpose range. Balanced appearance, workable stiffness and useful absorption once cells are opened. Common for wall linings, ceilings and sandwich-panel cores.
Fine, uniform surface for interior feature panels and furniture. In open-cell form the narrow pores give strong viscous damping of sound, at the price of lower permeability and higher cost.
Pore size is never perfectly uniform in a melt-route foam: a slab described as "5 mm" will contain smaller and larger cells. For visible applications, approve a physical sample from the actual production lot and agree how much variation in appearance is acceptable across a run of panels.
Mechanical behaviour of a metal foam depends mainly on its relative density (foam density divided by solid aluminium density). Strength rises roughly with the 1.5th power of relative density, so a small increase in density gives a large increase in strength. The figures below are indicative ranges for closed-cell construction foam; actual values vary with alloy, cell structure and test method, so specify the property you need and ask for test results to ISO 13314.
| Density (g/cm³) | Compressive plateau stress (MPa) | Bending strength (MPa) | Energy absorbed to 50 % strain (kJ/m³) |
|---|---|---|---|
| 0.25 – 0.30 | 3 – 4 | 3 – 5 | about 1,000 – 2,000 |
| 0.30 – 0.40 | 4 – 7 | 5 – 9 | about 2,000 – 3,000 |
| 0.40 – 0.50 | 7 – 11 | 9 – 13 | about 3,000 – 5,000 |
| 0.50 – 0.60 | 11 – 15 | 13 – 18 | about 5,000 – 7,000 |
| 0.60 – 0.70 | 15 – 19 | 18 – 22 | about 7,000 – 9,000 |
| 0.70 – 0.85 | 19 – 30 | 22 – 35 | about 9,000 – 15,000 |
Indicative values for closed-cell aluminium foam; not design values. Use certified test data for the specific product in any structural calculation.
Foam slabs or foam-core panels as a ventilated rainscreen layer on aluminium sub-frames. The textured face creates depth and changes with light; the material does not add fuel to a facade fire.
Lay-in or suspended panels where light weight reduces grid loads and where washability or moisture resistance matters, such as pools, kitchens, car parks and transport hubs.
Foam cores bonded between aluminium or steel faces give stiff, light, dry-assembled partitions. Combined with dense layers they can meet sound-insulation targets.
Opened closed-cell or open-cell foam over an air gap absorbs reverberant sound in halls, atriums, corridors and plant rooms. See the acoustic panel guide for test data.
Outdoor barriers that resist rain, UV and vehicle spray without losing absorption. Covered in detail on the foam noise barrier page.
Thick closed-cell slabs crush progressively at nearly constant stress, absorbing energy from impacts. Used in protective linings and as fillers in security doors.
Open-cell or perforated foam as decorative vents, louvre infills and light-diffusing screens that let air through.
Light, non-combustible decorative elements and protection layers; foam is not waterproof by itself, so it sits above a separate membrane.
Thin slices back-lit to create a translucent "froth" effect, or front-lit to show texture in lobbies, retail and hospitality interiors.
| Option | What it is | Typical use |
|---|---|---|
| Mill (natural) foam | Sliced surface with open cells exposed | Interior feature walls, ceilings, acoustic linings |
| Powder-coated or painted | Colour applied to the foam face; cells stay visible | Branded interiors, coloured facades |
| Anodised | Electrochemical oxide, clear or coloured | Higher durability on exterior foam faces |
| Resin- or acrylic-filled | Cells filled with clear or coloured resin and polished | Decorative panels, counters, furniture |
| Foam sandwich panel | Foam core bonded to aluminium sheet faces | Partitions, doors, cladding requiring a smooth face |
| Perforated-face composite | Micro-perforated aluminium face over a foam core | Acoustic walls and ceilings with a robust face |
Some suppliers describe foam panels that "withstand 1,000 °C". Aluminium melts at about 660 °C, so claims of this kind refer to a protected or composite build tested in a specific way, not to the foam itself. Ask for the exact test standard, the specimen build and the classification report before relying on a fire claim.
| Criterion | Aluminium foam panel | Aluminium composite panel (ACP) | Aluminium honeycomb panel | Solid aluminium sheet |
|---|---|---|---|---|
| Weight per area | Low | Low | Very low | Medium |
| Fire | Metal core, non-combustible | Depends on core (PE, FR or A2 mineral) | Metal core; adhesive affects class | Non-combustible |
| Sound absorption | Good when designed for it | Poor | Poor unless perforated | Poor |
| Impact energy absorption | Very good | Fair | Good | Fair |
| Appearance | Unique cellular texture | Flat, painted | Flat, painted or veneered | Flat, any finish |
| Relative cost | High | Low–medium | Medium–high | Medium |
If the brief is simply a flat, coloured, lightweight facade, an aluminium composite or honeycomb panel is usually cheaper. Aluminium foam is the stronger choice when the panel must also absorb sound, survive impact, stay non-combustible throughout or show a cellular metal face.
The foam is metal and does not burn, so it adds no fuel to a fire. It still melts at about 660 °C, and any adhesive, coating or composite layer affects the result, so classify the complete panel to EN 13501-1 or the local code.
Not by itself. Its conductivity is far lower than solid aluminium but still around a few W/m·K, much higher than mineral wool or PIR boards. Use a separate insulation layer behind foam cladding.
Yes. Closed-cell foam does not absorb water and resists weathering like other aluminium. On coastal or polluted sites, an anodised or coated face extends its life and keeps the appearance even.
Weight equals density times volume. A 1 m² panel 20 mm thick at 0.4 g/cm³ weighs about 8 kg; at 0.7 g/cm³ it weighs about 14 kg.
Closed-cell foam has sealed pores and is stiffer and waterproof; it suits cladding, cores and impact linings. Open-cell foam has connected pores, lets air through and absorbs sound without treatment.
Yes, with fine-tooth saws, band saws, waterjet or CNC routers. Use through-fixings or inserts rather than relying on screws biting into the foam.
Tell us the application, panel sizes, finish and quantity. We will recommend a foam type and supply the panels with matching aluminium profiles and sheet.
