Cleanroom Sandwich Panel Selection Guide: Cores & Fire Ratings

Cleanroom Sandwich Panel Selection Guide

In cleanroom enclosure structures, color-coated sandwich panels (cleanroom panels) account for the largest material volume—they form both the walls and the suspended ceilings. Because of this high volume, a single wrong decision in material selection can multiply costs exponentially across your total floor area.

A frequently asked question in the industry is: "Are rock wool panels better or hand-made panels better?"

This question itself mixes two different dimensions: rock wool refers to the core material, while hand-made refers to the construction method. A rock wool core can still be built as a hand-made panel, and hand-made panels are often filled with rock wool.

The correct logic for selecting cleanroom sandwich panels follows a simple three-step sequence: Determine the Construction Type - Select the Core Material - Verify Fire Safety Compliance.

The construction type dictates installation methods and costs; the core material determines fire resistance, structural rigidity, and moisture resistance; and the regulatory codes decide whether your chosen materials can pass project acceptance inspections.

I. Construction Type Selection: Machine-Made vs. Hand-Made Panels

The core distinction between these two lies in their manufacturing process, independent of the interior core material.

1. Machine-Made Panels (Tongue-and-Groove / Interlocking Panels)

Produced continuously on automated roll-forming lines, the panel edges are rolled directly into male and female tongue-and-groove profiles at the factory. The male edge protrudes outwards, completely wrapped in sheet steel; the female edge has its core material recessed, leaving only the top and bottom steel sheets to form a receiving channel. During installation, the male tongue is inserted fully into the female groove until the steel faces meet flush, and the surface seams are sealed with cleanroom silicone sealant.

• Ideal Applications:

The primary wall material for large-scale new construction cleanrooms. Standard modular widths (950 mm and 1150 mm) offer rapid supply and low unit cost, making them ideal for standardized cleanroom projects with tight schedules and budget constraints.

• Common Pitfalls & Risk Control:

The steel edges of tongue-and-groove joints are thin and susceptible to impact damage during transit. Deformed joints cannot be repaired on-site; incoming shipments must be spot-checked, and damaged batches rejected immediately. Seam sealing must be continuous without gaps, as joint airtightness serves as the first line of defense in cleanroom seal integrity. Machine-made panels are not recommended for areas requiring extensive on-site cutting, as cutting destroys the structural integrity of the tongue-and-groove joint.

2. Hand-Made Panels

Custom-manufactured individually, these panels feature metal profile frames wrapping all four edges before the face sheets and core material are laminated together. Panels are joined using "H-shaped" aluminum or steel splines, creating a metal-to-metal interlock that results in tight seams and high surface flatness.

• Ideal Applications:

  High-end cleanrooms, areas with strict visual appearance standards, irregular structural geometries, zones with numerous door/window cutouts, and non-standard dimensions. They offer superior wall flatness and refined perimeter trims, suited for rigorous validation standards at a higher budget.

• Common Pitfalls & Risk Control:

  Metal edge trims must be inspected upon arrival; warped frames or burrs inside the receiving channels will cause misaligned panel joints. Hand-made panels are heavier, requiring standardized handling and hoisting procedures on-site. Profile wall thickness must not be too thin; insufficient wall thickness leads to loose joints and uneven seam widths.

Selection Summary

• Large Area/ Standardized/Tight Schedule /Budget-Conscious - Machine-Made Panels

• High Specifications/Irregular Layouts/Premium Aesthetic Requirements -Hand-Made Panels

II. Core Material Selection: Locking Down Fire Safety Compliance

The core material directly determines the panel's fire rating, structural stiffness, weight, and moisture resistance. Both machine-made and hand-made panels can integrate various cores. Before selecting, strict adherence to mandatory cleanroom design codes is required:

According to GB 8624-2012 Classification for burning behavior of building materials and products, core materials on the market fall into three categories: Compliant Class A Non-Combustible, Class B1 Flame-Retardant (Non-Compliant for Acceptance), and Prohibited Organic Materials.

1. Class A Non-Combustible (Fully Compliant)  

① Rock Wool

The primary core material for cleanroom wall panels, rated Class A1 non-combustible. Standard bulk density ranges from 80 to 160 kg/m°,thermal conductivity≤ 0.044 W/(m · K), and fire resistance rating from 1 to 2 h (reaching up to 4 h when reinforced with glass magnesium boards). It is the default choice for general cleanroom wall panels.

Recommendation: Density should not be lower than 100 kg/m°;excessively low density results in soft panels, poor flatness, and susceptibility to denting.    

② Glass Magnesium Rock Wool (Single / Double Glass Magnesium)

A composite structure featuring a glass magnesium board frame filled with rock wool. The glass magnesium board provides structural rigidity while the rock wool delivers fire resistance and thermal insulation, outperforming pure rock wool. Single-layer reinforcement suits standard walls, while double-layer reinforcement is ideal for high-end cleanroom walls requiring elevated fire resistance ratings.

③ Hollow Glass Magnesium (Magnesium Oxychloride)

A traditional mainstay core for cleanroom suspended ceilings, featuring Class A non- combustibility,lightweight properties, and high cost-effectiveness. Its main drawback is moisture sensitivity; without proper humidity control during humid seasons, panels can bow by2-3 mm, leading to uneven surfaces over time. Exercise caution when specifying for projects with strict aesthetic requirements.

④ Magnesium Oxysulfate (MOS)

A modern alternative core for suspended ceilings offering Class A non-combustibility, a dense non-porous structure, superior moisture stability compared to glass magnesium, and lighter weight. Excellent for high-humidity environments and retrofit projects in older facilities.

Note: Because its history of large-scale application is relatively short, ask suppliers for case studies under similar operating conditions for high-stability projects.

2. Class B1 Flame-Retardant (Common Market Material; Non-Compliant for Standard Cleanrooms)

These materials are flame-retardant rather than non-combustible, failing to satisfy the mandatory "non-combustible body" requirement of cleanroom codes and causing failures during official fire inspections.

• Includes: Silica-Rock (Silicon-Rock) Boards, Aluminum Honeycomb, Paper Honeycomb.

• Note: Commonly used in general industrial partitions and basic electronic clean zones, but strictly prohibited in pharmaceutical, medical, and high-level cleanroom projects.

3. Organic Cores (Strictly Prohibited by Code)

• Includes: Polyurethane (PU), Expanded Polystyrene (EPS), Extruded Polystyrene (XPS).

• Note: Although offering superior thermal insulation, these are organic composite materials and are strictly prohibited for cleanroom walls and ceilings. They are restricted to cold storage facilities, temporary shelters, and non-cleanroom applications.

III. Face Sheet Selection: Surface Cleanliness, Corrosion & Static Resistance

The face sheet is the outermost protective layer directly exposed to the cleanroom environment. Regardless of core quality, selecting the wrong face sheet will compromise cleanliness and fail validation tests.

1. Color-Coated Steel Sheet (Industry Standard)

• PE (Polyester): Standard choice for general cleanrooms; offers the highest cost-effectiveness.

• SMP (Silicon Modified Polyester): Enhanced weatherability, suitable for long-term indoor durability.

• PVDF (Fluorocarbon): Superior chemical corrosion and weather resistance, ideal for environments with corrosive gases or high humidity.

2. 304 / 316 Stainless Steel Sheet

Dedicated to food, pharmaceutical, high-humidity, and frequently sanitized areas. Provides rustproof, dustproof, and easy-to-clean properties at a higher cost; typically reserved for critical zones.

3. Anti-Static Color-Coated SheetEssential for electronics cleanrooms, featuring a surface resistivity of 1×10⁶ to 1×10⁹ to prevent electrostatic dust accumulation.

4. Antimicrobial Coated Sheet

Designed for pharmaceutical plants, bio-laboratories, and hospital operating rooms. Features a silver-ion antimicrobial coating that actively inhibits bacterial growth on panel surfaces.

IV. Core Selection Logic Matrix

Cleanroom sandwich panels represent the largest material volume in cleanroom enclosure systems, leaving zero margin for error in selection. A minor difference in unit price multiplies into a massive cost variance across the entire footprint. More importantly, selecting the wrong core material or fire rating will lead to immediate failure during fire safety and cleanroom validation audits.