What Is a Sandwich Panel?
A sandwich panel is a prefabricated building material made of two outer steel sheets and a rigid insulating core, typically PUF (Polyurethane Foam), PIR (Polyisocyanurate), or EPS (Expanded Polystyrene). These panels are widely used for cold storage rooms, PEB structures, clean rooms, and industrial buildings because they provide excellent insulation, strength, and fast installation in one product.
The most common effective width for cold storage sandwich panels is 1190 mm, allowing for easy modular installation.
Standard Sheet & Panel Widths
Globally, steel coils used for sandwich panels come in different widths. The most common full-size PUF/PIR sheet is 1220 mm (4 feet) wide. After profiling (making low ribs or corrugations), the sheet shrinks slightly — usually by 20 to 30 mm — resulting in a final effective width of approximately 1190 mm.
Other widths include 1200 mm, 1180 mm, and 1150 mm. The exact effective coverage depends on the profile type and coil width. Always use the correct effective width when calculating panel quantities — not the full sheet width.
PUF vs PIR — Which Is Better?
PIR is better than PUF in almost every technical aspect. PIR offers better fire resistance, slightly better insulation (lower thermal conductivity), and better dimensional stability at high temperatures. However, PUF is more commonly used because it is more cost-effective and still offers excellent performance for most cold storage applications.
For critical applications where fire safety is a concern, PIR is the recommended choice.
Can Sandwich Panels Be Used for the Floor?
Yes, absolutely. In negative temperature rooms, floor insulation is critical to prevent condensation and heat gain from the ground. Typically, floors use XPS or PUF/PIR board sheets. But in many cases, especially when the floor finish is already done and owners do not want to break or insulate inside, sandwich panels are laid directly on the floor, and then a finishing sheet — such as checker sheet or aluminium sheet — is placed on top for durability.
Outer Skin Materials & Thickness
Common outer skin materials include:
- PPGI (Pre-Painted Galvanized Iron) — most common, cost-effective.
- Stainless Steel Sheets — for pharmaceutical, food processing, ice cream, and dairy storage.
- Aluminium Sheets — lightweight and corrosion-resistant.
- BlueScope Steel / Premium Branded Sheets — premium quality assurance.
Skin thickness typically ranges from 0.4 mm to 0.7 mm. The coating thickness (measured in microns) is equally important. A good PPGI sheet should have a coating of at least 20 microns, preferably more than 30 microns.
Panel Customization Based on Product Type
Not every cold room is the same. The type of product being stored directly affects panel specification, skin material, core density, and coating thickness. For example:
- Egg storage needs +4°C to +10°C
- Dried fruits +10°C to +20°C
- Bananas +15°C to +20°C
- Frozen products -15°C to -25°C
The golden rule: skin can be customized based on surface protection and hygiene, but the insulation core density and panel sealing should never be compromised.
Cold Storage Doors — Key Considerations
Door hardware must be top quality. Always install PVC curtains in front of cold room doors to contain cold air. For negative temperature rooms, door heaters are essential to prevent ice formation around the frame.
Common Mistakes to Avoid
- Forgetting wastage — always add 3–5% for cuts and waste.
- Using wrong effective width — many people use 1200 mm instead of 1190 mm.
- Ignoring panel orientation — panels can be installed vertically or horizontally.
- Not considering core material — using EPS for freezers may cause condensation.
- Underestimating roof support — long roof panels need proper purlins.