PU Steel Sandwich Panel

Product Introduction

PU Sandwich Panel is a top tier building material. Combining great insulation with strength, its three layer structure of rigid polyurethane foam between two metal facings is energy efficient for modern construction. It provides excellent thermal insulation, cutting heating and cooling costs. Lightweight, it eases installation and lessens structural load. With good fire resistance and soundproofing, it ensures safety and comfort. Durable, weather resistant, and low maintenance, it suits industrial, commercial, and residential roofing. Its versatility also offers functional and aesthetic advantages in different architectural designs.

Product Specifications

 The PU steel sandwich panel (Polyurethane Steel Composite Panel) is a high-performance building material composed of two outer steel sheets bonded to a rigid polyurethane (PU) foam core. It is widely used in industrial buildings, cold storage facilities, cleanrooms, modular homes, and energy-efficient enclosures due to its exceptional thermal insulation, mechanical strength, and fire-resistant performance.

This article explores the engineering design, material specifications, compliance with global standards, technical performance, and installation considerations of PU steel sandwich panels. It also addresses common user questions and ends with a professional industry-focused call to action.

What Is a PU Steel Sandwich Panel?

A PU steel sandwich panel is a structural insulated panel (SIP) made up of:

• Exterior and interior steel facings (usually pre-coated galvanized steel)

• A polyurethane or polyisocyanurate (PIR) rigid foam insulation core

• A continuous lamination or injection process that bonds these layers under heat and pressure

It is designed to offer superior thermal efficiency, fire retardancy, and mechanical integrity, making it ideal for both envelope and interior partition applications.

Key Materials and Configuration

Engineering Performance and Technical Characteristics

1. Thermal Insulation

• PU foam thermal conductivity: λ = 0.020–0.024 W/m·K

• Excellent for meeting ASHRAE, EN ISO 6946, and GB 50176 energy efficiency standards

• A 100mm panel can achieve U-values as low as 0.22 W/m²·K

2. Fire Resistance

• PU: Class B2 (self-extinguishing with flame retardants)

• PIR: Class B1 or Class A2-s1,d0 (EN 13501-1) with mineral additives

• Flame spread tested to ASTM E84, GB 8624, and FM 4880 standards

3. Compressive and Bending Strength

• Core compressive strength: ≥ 150–200 kPa

• Flexural strength: High due to rigid steel facings bonded to foam

• Can withstand wind suction pressures > 2.5 kN/m² (panel span-dependent)

4. Water and Vapor Resistance

• PU is closed-cell (>90%), providing high resistance to water absorption

• Optional vapor-tight joints prevent condensation in cold storage or humid environments

5. Acoustic Insulation

• Moderate (~24–28 dB), can be enhanced with acoustic membranes

• Not a primary application unless combined with other layers

Industry Standards and Certifications

Common Applications

Installation Guidelines and Engineering Considerations

Panel Fixing

• Installed using self-drilling screws with neoprene washers

• Joints can be tongue-and-groove, camlock, or hidden clip systems

• Sealants (PU foam or silicone) are recommended at joints for airtightness

Thermal Expansion and Fastening

• Allow ~2 mm/m for thermal expansion of steel skins

• Avoid over-tightening fasteners to prevent panel deformation

Fire Zones and Safety

• Use PIR core in areas requiring higher fire ratings

• For critical fire zones (e.g., exits, data centers), opt for rock wool core panels

Technical Performance Summary

Frequently Asked Questions (FAQs)

❓ What's the difference between PU and PIR sandwich panels?

• PU offers better thermal insulation, while PIR offers superior fire resistance

• PIR is typically preferred for buildings requiring strict fire codes

❓ Are PU sandwich panels waterproof?

Yes. The closed-cell PU foam has <2% water absorption by volume, and sealed joints ensure vapor resistance.

❓ Can I use PU panels for roofing?

Yes. PU panels are ideal for roof and wall systems, especially in cold climates. Roof panels come with trapezoidal profiles for structural strength.

❓ Are these panels environmentally friendly?

PU panels are energy-efficient and reduce long-term operational emissions. However, recyclability is limited compared to mineral wool panels.

❓ Can I paint the surface or apply other finishes?

The steel surface is typically coated with polyester (PE), PVDF, or SMP paints, available in any RAL color. It can also support screen printing or lamination.

Summary: Advantages of PU Steel Sandwich Panels