How to Select Core Material and Apparent Density of Sandwich Panel Cores

1. Core Material Overview & Recommended Density RangeCore Material	Fire Classification*	Typical Thermal Conductivity λ (W/m·K)	Recommended Density (kg/m³)	Key Characteristics
Basalt Rockwool	Class A Non-combustible	0.035–0.045	Partition: 100–110Wall/Roof: 120–140Fire Wall: 140–160	Outstanding fire resistance and sound insulation
PIR Polyisocyanurate	Class B1	0.020–0.024	38–42Cold Storage: 45–50	Excellent thermal performance and moisture resistance
PU Polyurethane	Class B2	0.018–0.023	32–38	High insulation efficiency and economical solution
EPS Polystyrene Foam	B1/B2	0.030–0.038	16–22	Lightweight and cost-effective
Glass Wool	Class A Non-combustible	0.038–0.048	Wall: 60–80Ceiling: 50–65	Lightweight with good acoustic performance

Fire classifications may vary depending on product certification and local regulations.

2. Recommended Selection by Application

Cold Storage & Temperature-Controlled Facilities

Recommended Core

PIR Sandwich Panel

Recommended Density

• Standard Cold Storage: 40 ± 2 kg/m³
• Deep Freezer : 45–50 kg/m³

Recommended Thickness

• Chilled Areas (0°C): 100 mm
• Freezer Rooms : 150 mm
• Ultra-Low Temperature : 200 mm

Steel Facing

• 0.5–0.6 mm Aluzinc-coated steel
• Concealed-joint or interlocking systems recommended to minimize thermal bridging

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Chemical Plants, Lithium Battery Facilities & High Fire-Risk Buildings

Recommended Core

• Hydrophobic Basalt Rockwool
• PU Edge-Sealed Rockwool Panels where enhanced thermal performance is required

Recommended Density

• External Wall: 130–150 kg/m³
• Roof: ≥120 kg/m³
• Fire Partition: 140–160 kg/m³

Recommended Thickness

• Partition Wall: 75–100 mm
• External Wall: 100–150 mm
• Roof: 120–150 mm

Class A non-combustible rockwool panels are strongly recommended and are often required for high fire-risk industrial applications.

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Pharmaceutical & Electronics Cleanrooms

Low-Temperature Cleanrooms

• PIR Core
• Density: 40–42 kg/m³

Fire-Critical Production Areas

• Rockwool Core
• Density: 125–135 kg/m³

Recommended Panel Types

• Machine-Made Cleanroom Panels
• Hand-Made Cleanroom Panels

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Industrial Factories & Warehouses

Cost-Focused Solution

• Fire-Retardant EPS
• Density: 19–21 kg/m³

Balanced Performance Solution

• PIR
• Density: 38–40 kg/m³

Enhanced Fire Protection Areas

• Rockwool
• Density: 110–120 kg/m³

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Temporary Buildings & Modular Housing

Short-Term Use

• EPS
• Density: 16–18 kg/m³

Long-Term Modular Buildings

• Fire-Retardant EPS: 20 kg/m³
• PIR: 35 kg/m³

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Acoustic Rooms & Equipment Enclosures

High Sound Insulation Requirements

• Rockwool: 120–130 kg/m³

Lightweight Acoustic Applications

• Glass Wool: 65–75 kg/m³

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3. Density Selection Guidelines

Rockwool Panels

• Below 100 kg/m³: Generally not recommended for industrial wall and roof systems.
• 100–120 kg/m³: Suitable for internal partitions.
• Above 120 kg/m³: Recommended for external walls and roofing systems.

PIR/PU Panels

• Below 35 kg/m³: Reduced compressive strength and dimensional stability.
• 38–42 kg/m³: Optimal specification for most industrial applications.
• 45–50 kg/m³: Recommended for cold storage and high-load environments.

General Principle

Higher density generally provides:

• Greater mechanical strength
• Better dimensional stability
• Improved impact resistance

However, excessive density may increase weight and project cost without proportional performance benefits.

GLOSTAR Recommended Solutions

Maximum Fire Protection

• Rockwool Sandwich Panel
• Density: 120–150 kg/m³

Best Thermal Performance

• PIR Sandwich Panel
• Density: 40–45 kg/m³

Best Overall Value for Industrial Buildings

• PIR Sandwich Panel
• Density: 38–40 kg/m³

Cost-Effective Temporary Structures

• EPS Sandwich Panel
• Density: 16–20 kg/m³

Acoustic Applications

• Rockwool Sandwich Panel
• Density: 120–130 kg/m³

This version reads like a professional engineering guide rather than a sales document, making it more credible to architects, consultants, contractors, and international buyers.