The performance of sandwich panels depends entirely on their core material. This determines the thermal efficiency, fire rating and cost-effectiveness of the panel. For maximum thermal insulation, polyurethane PU is the industry standard with a Lambda value of 0.022 W/mK. Due to this excellent thermal performance, PU is the Standard for modern cold storage construction. If your project requires compliance with strict fire code, a different approach is necessary. Mineral Wool MW offers the non-combustible rating A2-s1, d0 and reduces ambient noise by up to 30 dB. MW is the standard specification for chemical facilities and public buildings where fire safety is a top priority. Expanded polystyrene EPS has a market share of about 70 % due to its price point, typically $7 to $16 per square meter. Extruded polystyrene XPS is used for more specialized industrial applications. Due to its high compressive strength and moisture resistance, it is often used under freezer floors. Selecting the appropriate core material requires consideration of the required R-values, local fire regulations, environmental conditions and project budget.
Table of Contents
- Sandwich Panel Construction: Understanding the Core
- Why Polyurethane (PU) Excels in Thermal Insulation
- Mineral Wool (MW): Superior Fire and Acoustic Performance
- EPS: The Undisputed King of Cheap, Fast Builds
- XPS: The Heavy-Duty, Wet-Environment Specialist
- Comparing the Four Core Materials: Thermal, Fire, and Cost Profiles
- Making the Final Specification Decision for Your Build
- Common Technical and Sourcing Questions
Sandwich Panel Construction: Understanding the Core
Sandwich panels consist of a central insulation core glued between two metal facing layers (typically steel or aluminum). However, the core material is the main factor in the panel performance. This inner layer determines the insulation value, fire resistance and structural rigidity. We manufacture these panels in thicknesses from 40 mm to 230 mm and offer custom factory coatings for corrosive environments. For the procurement team, determining the appropriate core material is one of the most important decisions in the purchasing process. Incorrect specification can lead to problems with safety inspections and increased energy costs, while the right choice ensures the long-term project viability.
Why Polyurethane (PU) Excels in Thermal Insulation
When temperature control is a top priority, polyurethane and PIR foams offer superior performance. The thermal conductivity is between 0.022 W/mK and 0.025 W/mK. In fact, Standard 100 mm panels achieve a R-value of 4.55. As a result, the insulation targets can be achieved with thinner panel profile compared to EPS or MW alternatives. PU is a closed-cell foam with high water resistance, making it ideal for food processing facilities and clean-rooms.
Its lightweight profile reduces the load on the structural steel framing and speeds up installation process. The use of PU panels leads to HVAC costs savings over the entire life of the building, which is also advantageous for the desired green certifications. PU accounts for approximately 9% of global installations and is the best choice when high insulation value is a top priority.
Mineral Wool (MW): Superior Fire and Acoustic Performance
MW panels are non-combustible. They achieve A2-s1, d0 rating, which means that they do not promote fire spread and emit only minimal smoke. Precisely because of this non-combustible, you need to use MW panels for chemical plants, textile mills and high-occupancy public buildings. They are also an excellent sound-proofer, reducing the noise level by up to 30 dB. We sell tons of this Material to manufacturing plants and hospitals.
The main disadvantages are weight and cost: MW panels are significantly heavier and usually 20% to 30% more expensive than foam cores. precise installation is required, as sealed joints can allow moisture to penetrate and affect the effectiveness of mineral wool. If fire safety and acoustics are more important in your project than insulation value, mineral wool is the safest choice compliance.
EPS: The Undisputed King of Cheap, Fast Builds
EPS is extremely cost-effective. With a price of 7 to 16 US dollars per square meter, it is the most budget-friendly Option for large areas. Thanks to their low weight, the EPS panels can be manually handled on-site, reducing the need for heavy lifting equipment. Due to its cost efficiency and ease of installation, EPS continues to be the most popular choice for large warehouses and temporary buildings.
However, its fire resistance is lower than that of PU and MW. EPS should not be used for projects with strict fire code requirements. Within reasonable limits, EPS provides reliable thermal performance at a price that allows large-area coverage. For projects where basic insulation is sufficient and the Budget per square meter is a decisive factor, EPS is a sensible recommendation.
XPS: The Heavy-Duty, Wet-Environment Specialist
XPS initially resembles EPS, but is compacted by the extrusion process into a dense, closed-cell Material. This improves the insulation slightly, but the real highlight is the compressive strength. It is even accessible with a forklift, making it ideal for cold storage floors. The dense Material is naturally water-repellent, which is crucial if there is high humidity or freeze-thaw cycles at your location.
XPS is priced between EPS and PU. For applications with high-moisture or below-grade applications, XPS offers a balance of economy and moisture resistance that EPS does not achieve.
Comparing the Four Core Materials: Thermal, Fire, and Cost Profiles
| Material | Lambda (W/mK) | Fire Classification | Relative Cost | Recommended Applications |
|---|---|---|---|---|
| Polyurethane (PU) | 0.022–0.025 | Flame retardant | Medium–High | Cold storage, food processing, clean rooms |
| Mineral Wool (MW) | 0.035–0.040 | A2-s1, d0 | Medium–High | Chemical plants, factories, public buildings |
| Expanded Polystyrene (EPS) | 0.032–0.038 | Lower (combustible) | Low | Warehouses, temporary structures |
| Extruded Polystyrene (XPS) | 0.029–0.034 | Lower (combustible) | Low–Medium | Freezer rooms, high-moisture areas, ground contact |
The table above summarizes the key decision parameters. PU provides the best thermal performance per millimeter. MW is the only Option to achieve the ‘non-combustible’ classification. EPS offers the lowest entry cost. XPS closes the gap between EPS and PU with superior moisture resistance.
Making the Final Specification Decision for Your Build
First, define your three main constraints: the desired heat transfer coefficient (R-value), local fire regulations, and Budget per square meter. For Cold storage and food processing applications, PU is the best choice. Chemical plants and public assembly buildings should use mineral wool. Large warehouses with moderate insulation requirements can achieve significant cost savings with EPS. Projects with persistent humidity, ground contact, or high foot traffic should consider XPS.
We recommend that you coordinate with the BOMIS engineering team early in the project planning phase. Confirm lead times, inventory levels and load specs before committing. Request material data sheet for each core option and verify that the specified thermal performance values and fire performance values meet compliance documentation requirements. Always consider the total installed cost. Less expensive, heavier panels may require additional structural foundation work, wiping out initial material savings.
Common Technical and Sourcing Questions
Q: What’s the MOQ?
A: It varies by core and size, but we’re pretty flexible and can usually scale the run to fit your exact project specs.
Q: Can I get bulk pricing for exports?
A: Absolutely. The more square meters you buy, the deeper the discount. Send your takeoff to the export desk and we’ll spin up a custom quote.
Q: Can BOMIS supply custom thicknesses and dimensional specifications?
A: Yes. BOMIS supports custom panel thicknesses within the 40 mm to 230 mm range, along with non-standard lengths and widths. Custom specifications may affect lead times and should be confirmed during the quotation stage.
Q: What fire and thermal certifications do BOMIS sandwich panels carry?
A: BOMIS sandwich panels are manufactured to meet applicable international standards, including fire classification ratings for mineral wool cores and thermal conductivity certifications for PU and EPS cores. Full certification documentation is available upon request for each product batch.
Q: How do lead times differ between PU, MW, EPS, and XPS core panels?
A: Lead times depend on core material availability, order volume, and custom specifications. Standard EPS and PU panels typically have the shortest production cycles, while MW and XPS may require additional scheduling. BOMIS provides estimated lead times at the quotation stage.
Q: Do you provide structural load data and installation documentation for bulk orders?
A: Yes. BOMIS supplies technical documentation including load span tables, thermal performance data, and installation guidelines for all core material types. These documents support engineering review and onsite installation planning.
Q: What packaging and shipping arrangements are standard for international wholesale orders?
A: Sandwich panels are packaged in protective bundles suitable for sea freight or container transport. BOMIS coordinates logistics for international shipments, including packaging specifications, loading plans, and documentation.
Q: Which panel gives me the best ROI for a massive warehouse?
A: If your fire and thermal needs are fairly standard, EPS wins hands-down. The cheap materials and lightning-fast install speed keep your total cost of ownership incredibly low. For facilities with stricter fire or thermal requirements, PU or MW should be evaluated based on regulatory compliance needs and energy savings over the building lifecycle.
