Sandwich Panel Core Types: EPS, Rock Wool and PU Compared

Sandwich Panel Core Types: EPS, Rock Wool and PU Compared

Sandwich panels — two steel skins bonded to an insulating core — are the standard building material for cold rooms, factories, warehouses, clean rooms and modular buildings. The core material decides the panel's insulation, fire behavior, weight and price. This guide compares the three main cores (EPS, rock wool, PU/PIR) so you can choose the right product line for your market.

How Sandwich Panels Are Made

A sandwich panel production line feeds two color-coated steel skins from coil, injects or bonds the core between them, and presses, heats and cuts the continuous panel to length. Core type changes the line configuration: EPS and rock wool panels are assembled with adhesive or pre-formed slabs, while PU/PIR panels are foamed in place between the skins in a double-belt press.

EPS Panels

• Core: expanded polystyrene foam, 50-200 mm thick.
• Pros: cheapest core, very light, good thermal insulation, easy to cut and handle.
• Cons: combustible (fire rating limits), no sound damping, lower mechanical strength.
• Use: general roofing and wall cladding, temporary buildings, cold storage with fire-safety controls — the most popular panel in Africa, the Middle East and Asia.

Rock Wool (Mineral Wool) Panels

• Core: compressed mineral wool slab, 50-150 mm.
• Pros: fire-resistant (A-class, non-combustible), good sound and thermal insulation.
• Cons: heavier, more expensive, absorbs moisture if not sealed.
• Use: fire-rated walls and roofs, factories, kitchens, escape routes — required where building codes demand fire performance.

PU / PIR Panels

• Core: rigid polyurethane or polyisocyanurate foam injected between the skins.
• Pros: best thermal insulation per thickness, strong and rigid, ideal for cold rooms; PIR adds fire resistance.
• Cons: highest material cost; production needs a foaming line.
• Use: cold storage, freezers, clean rooms and projects where space or energy performance matters.

Comparison Table

Property	EPS	Rock wool	PU/PIR
Price	Low	Medium	High
Thermal insulation	Good	Good	Best
Fire rating	Combustible	Non-combustible (A)	B (PIR improved)
Weight	Light	Heavy	Light-medium
Sound damping	Poor	Excellent	Moderate
Typical use	General buildings	Fire-rated buildings	Cold rooms

Which Panel Line Should You Produce?

Choose by your market's demand and code requirements: EPS panels are the volume product in most emerging markets; rock wool is required where fire codes apply (factories, public buildings); PU/PIR serves cold-chain and high-performance projects. Many producers start with EPS and add rock wool capability as demand grows. A sandwich panel line can often be configured for EPS and rock wool with a core-cutting upgrade.

FAQ

What is the best sandwich panel core?

There is no single best — EPS is the economical general-purpose core, rock wool is required for fire-rated buildings, and PU/PIR gives the best insulation for cold rooms.

Which core is fire-resistant?

Rock wool (mineral wool) is non-combustible (A-class); PIR foam has improved fire behavior over PU and EPS.

Which core is used for cold rooms?

PU (polyurethane) is the standard cold-room core because it has the best insulation per thickness; PIR adds fire safety.

What is the cheapest sandwich panel core?

EPS (expanded polystyrene) is the lowest-cost core and the most common panel in emerging markets.

Can one line produce several core types?

EPS and rock wool can share a line with a core-cutting upgrade; PU/PIR foaming needs a dedicated double-belt line.

What panels should I start producing?

Start with the core your market demands most — EPS for general building markets, then add rock wool where fire codes require it.

Related Reading

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