Views: 0 Author: Site Editor Publish Time: 2026-06-24 Origin: Site
Project Background & Challenge
In 2023, a 40,000m² food processing plant in Shandong Province faced three critical issues with its existing metal roof:
Severe leakage: The old standing seam metal roof panels had failed at seam joints, causing water damage to production lines and raw materials.
High energy costs: The single-skin metal roof had no insulation, leading to extreme temperature fluctuations and HVAC bills exceeding $120,000 annually.
Fire safety risk: The previous roof system used EPS core panels (B2 fire rating), which did not meet updated local fire codes requiring A1 non-combustible materials for food processing facilities.
The client needed a complete roof replacement solution that would solve all three problems simultaneously.
2. Solution Selection
After evaluating multiple options, the project team selected Polyjoy metal roof sandwich panels from Hongxing Technology (Glostar brand). The chosen product was the TW PU Edge-Sealed Rock Wool Sandwich Panel with the following specifications:
Parameter | Value |
|---|---|
Panel thickness | 100mm |
Core material | Rock wool (density 120 kg/m³) |
Fire rating | A1 non-combustible (GB 8624) |
Thermal conductivity | 0.032 W/m·K |
Steel gauge | 0.6mm outer / 0.5mm inner |
Coating | PVDF (20-year warranty) |
Edge sealing | PU polyurethane edge seal |
Panel width | 1000mm |
Panel length | Custom up to 15m |
Why this product?
PU edge sealing provided 40% better waterproofing at joints compared to standard rock wool panels .
Rock wool core ensured A1 fire rating with 120-minute fire resistance at 100mm thickness .
PVDF coating offered 20-year durability in the coastal Shandong environment .
Steel roof sandwich panels with hidden fastener design eliminated through-penetration leakage points.
3. Installation Process
The installation was completed in 25 days by a team of 12 workers, using the following method:
Substructure preparation: Existing purlins were inspected and reinforced where needed.
Panel placement: Panels were lifted by crane and positioned using tongue-and-groove interlocking.
Fastening: Hidden clips secured panels without penetrating the surface, maintaining waterproof integrity.
Edge sealing: All end joints were sealed with PU foam and silicone sealant.
Flashing & trim: Custom flashings were installed at ridge, eave, and valley locations.
The insulated metal roof panels were installed in a standing seam configuration, allowing for thermal expansion without compromising seal integrity.
4. Measurable Results
After 3 years of operation, the project delivered the following outcomes:
Metric | Before | After | Improvement |
|---|---|---|---|
Roof leakage incidents | 12 per year (average) | 0 | 100% elimination |
Annual HVAC energy cost | $125,000 | $75,000 | 40% reduction |
Interior temperature fluctuation | ±8°C | ±2°C | 75% improvement |
Fire rating compliance | B2 (non-compliant) | A1 (fully compliant) | Passed inspection |
Maintenance cost per year | $15,000 | $2,000 | 87% reduction |
Client testimonial:
"The Polyjoy metal roof sandwich panels solved our biggest headache. Not a single leak in three years, and our energy bills dropped dramatically. The installation team was professional and completed the work ahead of schedule."
— Plant Manager, Shandong Food Processing Co.
5. Why This Solution Works for Industrial Roofs
5.1 Superior Waterproofing
The PU roof sandwich panels feature a polyurethane edge seal that creates a continuous barrier at panel joints. This is critical for low-slope industrial roofs where water pooling is common. The hidden fastener system eliminates the #1 cause of metal roof leaks: fastener penetration.
5.2 Energy Efficiency
With a thermal conductivity of just 0.032 W/m·K, the rock wool roof panels provide excellent insulation. In summer, the roof reflects solar heat (PVDF coating has 70% solar reflectance), while in winter, the rock wool core retains interior heat. This dual action reduced HVAC load by 40%.
5.3 Fire Safety
The A1 fire rating of the rock wool core means the panels will not burn, melt, or produce toxic smoke in a fire. This is mandatory for food processing, pharmaceutical, and chemical facilities. The steel roof sandwich panels also provide 120-minute fire resistance, giving occupants time to evacuate.
5.4 Long-Term Durability
The PVDF coating on the metal roof sandwich panels is tested to withstand 20 years of UV exposure without chalking or fading. The rock wool core is hydrophobic (≥98% water repellency), so even if the outer skin is damaged, the insulation will not absorb moisture and lose performance .
6. Comparison with Alternative Roof Systems
Feature | Polyjoy Metal Roof Sandwich Panels | Traditional Standing Seam Metal Roof | Built-up Roof (BUR) |
|---|---|---|---|
Insulation | Built-in (rock wool) | Requires separate insulation layer | Requires separate insulation |
Fire rating | A1 (non-combustible) | B1 (steel only) | Varies (often B2) |
Installation speed | 600-800 m²/day | 200-300 m²/day | 150-200 m²/day |
Lifespan | 20+ years | 15-20 years | 10-15 years |
Maintenance | Low (no exposed fasteners) | Medium (seam maintenance) | High (membrane repairs) |
Cost per m² (installed) | $28-35 | $25-30 (plus insulation cost) | $20-25 (plus insulation) |
7. Key Takeaways for Specifiers
For roof leakage problems: Choose metal roof sandwich panels with PU edge sealing and hidden fasteners. This eliminates the most common failure points.
For energy savings: Select insulated metal roof panels with rock wool or PIR core. A 100mm thick panel can reduce HVAC costs by 40% or more.
For fire safety: Mandate A1 fire rated rock wool roof panels. This is non-negotiable for food, pharmaceutical, and public buildings.
For coastal or corrosive environments: Specify PVDF coating on steel roof sandwich panels for 20-year durability.
For fast installation: Choose PU roof sandwich panels with tongue-and-groove interlocking. A 40,000m² roof can be completed in 25 days with a small crew.
8. Conclusion
This real-world case proves that metal roof sandwich panels from Hongxing Technology (Polyjoy brand) are the optimal solution for industrial roofs requiring waterproofing, energy efficiency, and fire safety. The combination of PU edge sealing, rock wool core, and PVDF coating delivered measurable results: zero leaks, 40% energy savings, and full A1 fire compliance. For your next industrial roofing project, consider the proven performance of steel roof sandwich panels from Glostar.
For detailed product specifications and project quotations, contact Hongxing Technology at +86-400-870-4088 or visit www.glostar.cn.
