Introduction: Engineering Precision in Insulated Panel Systems
In the world of modern construction for industrial, commercial, and cold chain facilities, sandwich panels represent a critical building envelope technology. Their performance is not determined by a single characteristic but by a precise combination of material properties, dimensions, and engineered features. As a leading manufacturer with deep expertise in both PIR sandwich panels and rock wool sandwich panels, ZHUOZHU provides this definitive specification guide. Understanding these technical parameters is essential for architects, engineers, and project managers to select the right panel system that meets structural, thermal, fire safety, and acoustic requirements while ensuring optimal lifecycle performance and cost-efficiency.
Part 1: PIR (Polyisocyanurate) Sandwich Panel Specifications
PIR panels represent the premium standard for thermal efficiency in foam-cored insulated panels, offering exceptional performance in cold room, controlled environment buildings, and energy-conscious construction.
Core Material & Composition
- Primary Core: Rigid, closed-cell Polyisocyanurate (PIR) foam.
- Advanced Option: PU edge-sealed PIR core for enhanced thermal continuity at joints, minimizing thermal bridging—a critical feature for low-temperature applications.
- Chemical Structure: PIR is a thermoset polymer created through a controlled reaction of isocyanates and polyols, forming a stable, cross-linked cellular structure with inherent fire-resistant properties.
Density & Structural Properties
- Core Density: 40-45 kg/m³ (typical range). This density provides an optimal balance between thermal performance, mechanical strength, and weight.
- Compressive Strength: ≥ 150 kPa (at 10% deformation, per EN 826), ensuring dimensional stability under load and resistance to facing indentation.
- Dimensional Stability: Excellent resistance to thermal cycling and humidity, with minimal long-term shrinkage or warping.
Panel Dimensions & Configuration
- Panel Thickness: Available in standard increments: 50mm, 75mm, 100mm, 120mm, 150mm, 200mm. Custom thicknesses available for specialized applications.
- Effective Width: Standard module of 1000mm (post-installation). Other common widths include 950mm and 1150mm depending on joint design and regional standards.
- Panel Length: Custom manufactured to project specifications, typically up to 16 meters for wall panels and 12 meters for roof panels, limited by transport logistics. Longer lengths possible with special arrangements.
- Tolerance: Thickness: ±1.5mm; Width: ±2mm; Length: ±5mm.
Panel Skin (Facing) Options
- Material: Pre-coated galvanized steel (SGCC, DX51D+Z), stainless steel (for hygienic applications), or aluminum.
- Coating: Standard Polyester (PE), durable Polyvinylidene Fluoride (PVDF/HDP), or Plastisol for enhanced corrosion resistance. Color options per RAL chart.
- Thickness: 0.5mm to 0.8mm for walls, 0.7mm to 1.0mm for roofs (subject to span and load requirements).
- Profile: Micro-rib, trapezoidal, or flat profiles available.
Performance Specifications
- Thermal Performance (U-Value):
- 50mm: U ≈ 0.45 W/m²K | R ≈ 2.22 m²K/W
- 100mm: U ≈ 0.23 W/m²K | R ≈ 4.35 m²K/W
- 150mm: U ≈ 0.15 W/m²K | R ≈ 6.67 m²K/W
- *PUR Core λ-value: 0.022 – 0.024 W/m·K(PIR: 0.024 W/m·K)*
- Fire Rating: Typically Class B-s1,d0 according to EN 13501-1 (Limited combustibility, very limited smoke production, no flaming droplets). Can achieve up to Class A2-s1,d0 with specific facings and formulations.
- Sound Insulation: Rw ≈ 25-30 dB (for 100mm panel). Primarily a function of mass law; improved with asymmetrical facing weights.
- Joint Type: Tongue-and-Groove (T&G) with integrated EPDM gasket for airtight, watertight seal. Alternative: concealed fix systems for architectural applications.
Application & Characteristics
- Primary Application: Cold room panels, temperature-controlled warehouses, industrial buildings, cleanroom anterooms, and roofing systems where high thermal efficiency is paramount.
- Structural Integrity: Excellent load-bearing capacity for both distributed and concentrated loads. Suitable for roof spans up to 6m (depending on thickness and loading). High bending stiffness.
- Surface: Smooth, factory-finished surface requiring no additional treatment. Highly cleanable and resistant to most chemicals used in food and industrial environments.
- Weight: Approximately 10-12 kg/m² for a 100mm thick panel with 0.5mm steel facings, facilitating faster installation and reducing structural load.
Part 2: Rock Wool (Stone Wool) Sandwich Panel Specifications
Rock wool panels are the definitive choice for applications where fire safety is the primary concern, offering non-combustible performance combined with good thermal and acoustic properties.
Core Material & Composition
- Primary Core: Rock wool (stone wool) mineral fiber, made from basalt rock and recycled slag, spun into a wool-like mat and bonded with a thermosetting resin.
- Advanced Option: PU edge-sealed rock wool core—a hybrid system where rock wool provides the fire-resistant core while a continuous polyurethane seal at the panel edges dramatically improves thermal performance at joints and prevents edge thermal bridging.
Density & Structural Properties
- Core Density: 80-120 kg/m³ (standard range for sandwich panels). Higher densities (up to 150 kg/m³) available for enhanced acoustic or structural performance.
- Compressive Strength: ≥ 40 kPa (at 10% deformation). Lower than PIR but sufficient for wall applications and supported roofing.
- Dimensional Stability: Inorganic and non-hygroscopic. Will not shrink, warp, or settle over time. Maintains performance even when wet.
Panel Dimensions & Configuration
- Panel Thickness: Standard range: 50mm, 80mm, 100mm, 120mm, 150mm. Thicker panels up to 200mm available.
- Effective Width: Typically 1000mm. Can be manufactured in 950mm or 1150mm to suit specific framing systems.
- Panel Length: Standard up to 12 meters. Shorter lengths are more common due to core material characteristics and weight considerations.
- Tolerance: Thickness: ±2mm; Width: ±3mm; Length: ±5mm.
Panel Skin (Facing) Options
- Material: Galvanized steel, galvalume, or stainless steel. Heavier gauges often used to compensate for lower core stiffness.
- Coating: Standard Polyester (PE), PVDF, or fire-retardant intumescent coatings for specialized applications.
- Thickness: 0.6mm to 1.0mm typical, with thicker facings recommended for longer spans.
- Profile: Generally stiffer profiles than PIR panels to enhance panel rigidity.
Performance Specifications
- Thermal Performance (U-Value):
- 80mm: U ≈ 0.45 W/m²K | R ≈ 2.22 m²K/W
- 100mm: U ≈ 0.36 W/m²K | R ≈ 2.78 m²K/W
- 150mm: U ≈ 0.24 W/m²K | R ≈ 4.17 m²K/W
- *Core λ-value: 0.033 – 0.040 W/m·K*
- Fire Rating: Class A1 (non-combustible) according to EN 13501-1—the highest possible fire classification. Contributes zero to fire load.
- Sound Insulation: Rw ≈ 35-45 dB (for 100mm panel). Superior acoustic performance due to the dense, fibrous core that absorbs sound energy.
- Joint Type: Shiplap or T&G joints, often with additional fire-resistant mineral wool strips inserted during installation for maintaining fire compartment integrity.
Application & Characteristics
- Primary Application: Fire walls and partitions, industrial building envelopes where fire codes are stringent, steel structure protection, acoustic barriers, and areas adjacent to high-heat processes.
- Structural Integrity: Good compressive strength but lower bending stiffness compared to PIR. Requires closer purlin spacing (1.2m-1.5m typical). Excellent for vertical wall applications.
- Surface: Can be finished with the same high-quality coatings as PIR panels. The core itself is hydrophobic but requires intact facings to prevent fiber release.
- Weight: Approximately 15-20 kg/m² for a 100mm thick panel, making it heavier than equivalent PIR panels. This affects handling, installation speed, and structural support requirements.
Part 3: PU Edge-Sealed Rock Wool Panels – The Hybrid Solution
Technical Innovation
This advanced system combines the core strengths of both materials:
- Core: Standard rock wool for Class A1 fire safety.
- Edge Treatment: A continuous polyurethane foam seal injected along all four panel edges during manufacturing.
- Purpose: Creates a complete thermal break at the panel perimeter, addressing the primary weakness of traditional rock wool panels—heat transfer through the metal edge returns.
Enhanced Performance Characteristics
- Thermal Bridging Reduction: Ψ-value (linear thermal transmittance) at joints reduced by 60-70% compared to standard rock wool panels.
- Airtightness: The PU seal provides superior air infiltration resistance, improving overall building envelope performance.
- Condensation Risk: Significantly lowers the risk of interstitial condensation at panel joints in cold climate applications.
- Application Ideal For: Buildings requiring both maximum fire safety (A1) and high thermal efficiency, such as cold storage facilities with strict fire codes, pharmaceutical plants, and high-specification industrial facilities.
Part 4: Comparative Summary & Selection Guidelines
| Specification Parameter | PIR Sandwich Panel | Rock Wool Sandwich Panel | PU Edge-Sealed Rock Wool |
|---|---|---|---|
| Best For | Optimal thermal efficiency, cold storage, energy-saving roofs | Maximum fire safety, fire walls, acoustic control, steel protection | Combined A1 fire safety with enhanced thermal performance |
| Thermal Efficiency | ★★★★★ (Excellent) | ★★★☆☆ (Good) | ★★★★☆ (Very Good) |
| Fire Safety | ★★★☆☆ (Class B to A2) | ★★★★★ (Class A1) | ★★★★★ (Class A1) |
| Acoustic Performance | ★★☆☆☆ (Fair) | ★★★★★ (Excellent) | ★★★★★ (Excellent) |
| Weight | Lightweight | Heavy | Heavy |
| Moisture Resistance | Excellent (closed cell) | Good (hydrophobic) | Excellent (sealed edges) |
| Cost Consideration | Moderate | Higher | Premium |
| Typical Span Capacity | High | Moderate | Moderate |
Selection Methodology:
- Prioritize Fire Code: If regulations mandate non-combustible (A1) materials, choose rock wool or its PU-sealed variant.
- Evaluate Thermal Needs: For ultra-low temperature or high-energy-efficiency focus, PIR is typically optimal unless fire codes override.
- Consider Total System Cost: Include installation speed (lighter PIR panels install faster), structural support needs (heavier rock wool may require stronger framing), and lifecycle energy savings.
Precision Specification for Project Success
Selecting between PIR sandwich panels, rock wool sandwich panels, or advanced hybrid systems is not merely a product choice but an integral engineering decision that impacts building safety, operational costs, and regulatory compliance. Each specification parameter—from core density and thickness to joint type and facing selection—interacts to define the final performance envelope.
ZHUOZHU’s manufacturing expertise ensures that these specifications are not just theoretical values but guaranteed performance characteristics delivered in every panel. Our technical support team works with clients to navigate these specifications, ensuring the selected system aligns perfectly with project requirements for structural integrity, thermal performance, fire safety, and acoustic control.
By understanding and correctly applying these detailed specifications, project teams can create buildings that are not only compliant but optimized for their specific purpose—whether it’s protecting sensitive pharmaceuticals, ensuring food safety, manufacturing advanced electronics, or simply creating an energy-efficient, comfortable industrial workspace.
About the Author
Wald is the Chief Engineer at ZHUOZHU, with a Bachelor’s degree in Building Materials Engineering and over 8 years of specialized experience in insulated panel systems. His work focuses on the relationship between material specifications and in-field performance, helping clients globally optimize their building envelope selections. Learn More About Us
