Foam Insulation

What Is Foam Insulation?

Foam insulation boards are rigid insulation products made primarily from two closed-cell plastic materials: expanded polystyrene (EPS) and extruded polystyrene (XPS). Both are moisture resistant, offer strong thermal performance, and can be cut to fit almost any space — making them a reliable choice across wall, ceiling, underfloor, and slab applications.

EPS Foam Insulation

EPS insulation is a closed-cell structure made from expanded polystyrene beads fused together to form a cellular plastic board material. It's one of the most widely used foam insulation products in Australian construction thanks to its combination of performance and affordability.

Key benefits of EPS insulation:

• Excellent thermal insulation properties
• Maintains stable internal temperatures year-round
• Reduces energy usage, helping lower energy bills
• Lightweight, rigid structure allows for fast, easy installation
• Can be cut to fit any space, including irregular or unusual areas

XPS Foam Insulation

XPS insulation is a closed-cell, extruded polystyrene board known for its water resistance and high compressive strength. Because its closed-cell structure is unaffected by moisture, XPS insulation retains its R-value even in damp or below-grade conditions — and is designed to hold that R-value for the lifetime of the building.

Key benefits of XPS insulation:

• High compressive strength for demanding applications
• High resistance to heat flow and low thermal conductivity
• Moisture and water resistant, even in below-ground conditions
• Lightweight and easy to handle on site
• Non-irritant and safe for DIY installation

Foilboard Insulation Panels

Foilboard combines a rigid foam core with a reflective foil facing, giving it the dual benefit of foam's structural insulation and foil's radiant heat reflection. It's a popular choice for roof spaces, sheds, and walls where managing radiant heat is just as important as insulating against conductive heat loss.

Open-Cell vs Closed-Cell Foam Insulation

Not all foam insulation performs the same way, and the difference comes down to cell structure:

• Open-cell foam contains inflating agents that allow it to expand and compress easily. It has a lower density, making it lighter but generally less durable under compression.
• Closed-cell foam — the structure used in both EPS and XPS insulation — is denser and solid, giving it far greater resistance to compression, moisture ingress, and long-term wear.

For most structural and below-grade applications, closed-cell foam is the preferred choice due to its durability and moisture performance.

Thermal Performance and R-Value

Every foam insulation product is rated by its R-value — a measure of its resistance to heat flow. A higher R-value means better thermal performance, which translates directly into lower energy usage and greater energy bill savings.

R-values matter more than most homeowners realise: even a small gap in coverage can allow significant heat loss or heat gain, undermining the performance of an otherwise well-insulated home. That's why we stock foam insulation across a full range of R-values — from R1.5 through to R7.0 — so you can match the right product to your climate zone, application, and building requirements.

Where Foam Insulation Is Used

Foam insulation panels and boards are suited to a genuinely wide range of applications, including:

• Wall insulation — EPS, XPS, and Foilboard panels help prevent airflow, heat loss, and heat intrusion through external and internal walls, while also improving sound protection and reducing disturbing outside noise.
• Ceiling insulation — maintains stable internal temperatures and reduces the load on heating and cooling systems.
• Underfloor and subfloor insulation — foam boards resist moisture from the ground while insulating against heat loss through the floor.
• Garage door insulation — a commonly overlooked area where foam panels make a noticeable difference to comfort and temperature control.
• Slab edge and under-slab insulation — critical for reducing ground-level heat loss (see below).
• Between floors — helps manage both thermal transfer and noise between levels of a building.
• Cavity walls, flat roofs, and cool rooms — XPS insulation is well suited to specialised commercial and refrigeration applications thanks to its moisture resistance and long-term R-value retention.

Concrete Slab and Under-Slab Insulation

Up to 25% of a building's heat loss can occur through uninsulated areas below ground, including foundations and concrete slabs. Because below-grade insulation is constantly exposed to moist soil, it needs to be genuinely water and moisture resistant while drying quickly if exposed to dampness — which is exactly why XPS insulation is the preferred material for this application.

Slab insulation helps maintain stable slab temperatures despite fluctuating ground-level temperatures across most of Australia, reducing heat loss to the ground in winter and minimising heat gain from the ground in summer.

Under the Building Code of Australia (BCA), slab-edge insulation is mandated wherever heating is installed within the slab — whether that's hydronic heating (which circulates solar-heated water through the building and foundation slab) or electric resistance heating (attached to the reinforcement before the slab is poured). Properly installed under-slab and slab-edge insulation allows the temperature at and just below ground level to be moderated and maintained, protecting the effectiveness of the heating system above it.

Why Choose Foam Insulation

• Durability — rigid, closed-cell structures resist compression, moisture, and long-term wear.
• Energy efficiency — reduces reliance on heaters and air conditioners, lowering both energy usage and environmental impact.
• Acoustic performance — dense foam structures help soundproof walls and reduce noise transfer.
• Moisture control — closed-cell foam resists condensation, helping prevent mould and rust over time.
• Easy handling — lightweight, non-toxic, and simple to cut and install, making it a practical option for both licensed installers and confident DIYers.
• Long-term value — foam insulation is a cost-effective investment that continues delivering energy savings for the life of the building.

Shop Our Foam Insulation Range

We stock a comprehensive range of foam insulation panels and boards from trusted brands, including Foamex, Foilboard, Kingspan, Fletcher Insulation, Metecno, and Trade Select by Ametalin — covering EPS, XPS, and Foilboard products across every R-value and application. Get in touch with our team for help selecting the right foam insulation for your project.