Last updated: May 15, 2026
Quick Answer
Sandwich panel thickness is determined by four primary factors: thermal insulation requirements, structural load demands, fire resistance ratings, and local building codes. For most commercial and industrial buildings in moderate climates, 50mm to 100mm panels cover the majority of wall and roof applications. Cold storage or cold-climate construction typically requires 100mm to 200mm or more.
Key Takeaways
- Thermal performance is the single biggest driver of thickness selection — thicker panels have lower U-values and better insulation.
- 50mm panels suit interior partitions and mild-climate cladding; 75–100mm covers most standard commercial walls and roofs.
- 150mm–200mm panels are standard for cold rooms, freezer facilities, and high-insulation industrial buildings.
- Structural span and wind/snow load requirements can independently force a thicker panel even when insulation needs are modest.
- Fire resistance ratings (typically 30, 60, or 120 minutes) influence both core material choice and minimum thickness.
- Local building energy codes set minimum thermal resistance (R-value or U-value) thresholds — always check these before specifying.
- Cost increases with thickness, but under-specifying thickness leads to higher long-term energy bills and potential code non-compliance.
- Core material (PIR, EPS, mineral wool, PUR) affects how much thickness is needed to hit a target U-value.
Why Sandwich Panel Thickness Matters More Than Most Buyers Realize
Choosing the wrong panel thickness is one of the most common and costly mistakes in construction projects. A panel that is too thin fails to meet energy codes, drives up heating and cooling costs, and may not carry the required structural load. A panel that is unnecessarily thick adds material cost, weight, and complexity without delivering proportional benefit.
Understanding how to choose sandwich panel thickness correctly means balancing thermal, structural, acoustic, and fire performance requirements against budget and project constraints. This guide walks through each factor systematically so specifiers, contractors, and buyers can make a confident, code-compliant decision.
What Are the Standard Sandwich Panel Thicknesses Available?
Standard sandwich panel thicknesses range from 30mm to 250mm, with the most commonly stocked sizes being 50mm, 75mm, 100mm, 120mm, 150mm, and 200mm.
Most manufacturers offer panels in these increments:
| Thickness | Typical Application |
|---|---|
| 30–50mm | Interior partitions, decorative cladding |
| 75mm | External walls in mild climates |
| 100mm | Standard commercial roofs and walls |
| 120–150mm | Cold climates, refrigerated warehouses |
| 175–200mm | Freezer rooms, cold storage, extreme climates |
| 200mm+ | Deep-freeze facilities, specialized industrial |
Decision rule: If the project is a standard warehouse or factory in a moderate climate, start with 100mm as a baseline and adjust based on the thermal and structural calculations below.
For a full overview of available panel options, see the sandwich panel products range to compare specifications by thickness and core type.
How Does Thermal Performance Drive Thickness Selection?
Thermal performance is the primary reason most projects specify a particular thickness. Thicker panels trap more air within the insulating core, reducing heat transfer and lowering the U-value (measured in W/m²K — the lower, the better).
How to use U-value targets to select thickness:
- Check the local building energy code for the minimum thermal resistance required for walls and roofs.
- Identify the core material being used (PIR, PUR, EPS, or mineral wool — each has a different thermal conductivity, or lambda value).
- Use the formula: U-value ≈ lambda / thickness (simplified; actual calculation includes facing layers and thermal bridges).
- Select the thickness that meets or slightly exceeds the code minimum.
Approximate U-values by thickness for PIR core panels (lambda ≈ 0.022 W/mK):
| Thickness | Approximate U-value |
|---|---|
| 60mm | ~0.35 W/m²K |
| 80mm | ~0.27 W/m²K |
| 100mm | ~0.22 W/m²K |
| 120mm | ~0.18 W/m²K |
| 150mm | ~0.14 W/m²K |
| 200mm | ~0.11 W/m²K |
Note: These are indicative estimates based on typical PIR lambda values. Always request certified thermal data from the manufacturer for your specific panel product.
Common mistake: Specifying thickness based on cost alone without checking the local U-value requirement. This often results in a panel that fails the energy compliance check and requires costly replacement.
How Do Structural and Load Requirements Affect Thickness?
Beyond insulation, sandwich panels must carry their own weight plus imposed loads such as wind pressure, snow accumulation, and foot traffic on roofs. Thicker panels have greater bending stiffness and can span longer distances between supports.
Key structural considerations:
- Span length: Longer purlin or girt spacing requires a stiffer, often thicker panel to avoid excessive deflection.
- Wind load zone: High-wind regions (coastal or cyclone-prone areas) demand panels with higher lateral resistance.
- Snow load: Roof panels in cold regions must carry snow accumulation without exceeding deflection limits.
- Point loads: Roof panels used for maintenance access need higher concentrated load capacity.
Decision rule: If the structural span exceeds 3 meters, or if the site is in a high-wind or heavy-snow zone, request a structural load table from the manufacturer and verify the panel passes before finalizing thickness.
Structural performance data is product-specific. Always ask the sandwich panel manufacturer for certified load-span tables before specifying.
How to Choose Sandwich Panel Thickness for Different Building Types
The right thickness varies significantly by building type and use. Here is a practical breakdown:
Commercial and industrial buildings (warehouses, factories):
- Walls: 75–100mm (moderate climate), 100–120mm (cold climate)
- Roofs: 100mm minimum; 120–150mm in colder or energy-sensitive applications
Cold rooms and refrigerated warehouses:
- Chilled storage (0–5°C): 100–150mm
- Freezer rooms (-18°C to -25°C): 150–200mm
- Deep-freeze (-30°C and below): 200mm+
For dedicated cold storage construction, the sandwich panel room guide covers specific thickness and core material recommendations.
Clean rooms and pharmaceutical facilities:
- Typically 75–100mm with PIR or mineral wool core for hygiene and fire compliance
Residential and modular buildings:
- Walls: 50–75mm in tropical climates; 100mm+ in temperate or cold zones
- Roofs: 100mm is a common starting point
Agricultural buildings:
- Often 50–75mm for walls where thermal performance is less critical
- Roofs may need 100mm if the building houses livestock or temperature-sensitive produce
How Does Core Material Change the Thickness You Need?
Core material directly affects how much thickness is required to achieve a given thermal performance. Two panels of the same thickness but different cores can have significantly different U-values.
Core material comparison:
| Core Material | Thermal Conductivity (lambda) | Fire Performance | Typical Use |
|---|---|---|---|
| PIR (Polyisocyanurate) | ~0.022 W/mK | Good (Class B–C) | Roofs, walls, cold rooms |
| PUR (Polyurethane) | ~0.023 W/mK | Moderate | General construction |
| EPS (Expanded Polystyrene) | ~0.035–0.040 W/mK | Lower | Low-cost applications |
| Mineral Wool | ~0.035–0.040 W/mK | Excellent (Class A) | Fire-rated applications |
Practical implication: To achieve the same U-value as a 100mm PIR panel, an EPS panel would need to be approximately 150–180mm thick. Mineral wool panels also require greater thickness for equivalent thermal performance but offer superior fire resistance.
Decision rule: Choose mineral wool core if the project requires a 60-minute or 120-minute fire resistance rating. Choose PIR or PUR for maximum thermal efficiency at minimum thickness.
How to Choose Sandwich Panel Thickness: A Step-by-Step Process
Following a structured process prevents the most common specification errors.
Step 1: Confirm the application
Identify whether the panel is for a wall, roof, floor, or partition. Each has different load and thermal requirements.
Step 2: Check local building codes
Obtain the minimum U-value or R-value requirement for the specific climate zone and building type.
Step 3: Select the core material
Based on fire rating requirements and budget, choose between PIR, PUR, EPS, or mineral wool.
Step 4: Calculate required thickness
Use manufacturer thermal data or the simplified U-value formula to find the minimum thickness that meets the code.
Step 5: Check structural load requirements
Verify the selected thickness passes the span and load requirements for the project's structural grid.
Step 6: Check fire resistance requirements
Confirm the panel meets the required fire resistance rating (30, 60, or 120 minutes) at the chosen thickness and core.
Step 7: Get a quote and compare
Thickness affects price significantly. Compare options across suppliers and weigh the cost difference against long-term energy savings.
For competitive pricing by thickness, the sandwich panel price guide provides a useful reference point.
Step 8: Confirm with the manufacturer
Always request certified test data and technical data sheets before placing an order. Work with a reputable sandwich panel manufacturer and supplier who can provide project-specific guidance.
What Are the Most Common Mistakes When Selecting Panel Thickness?
Even experienced specifiers make avoidable errors. Here are the most frequent ones:
- Ignoring local energy codes: Selecting a thickness based on cost or habit without checking the current code minimum.
- Confusing wall and roof requirements: Roofs typically need better insulation than walls because heat rises — using the same thickness for both often under-insulates the roof.
- Overlooking thermal bridging: Joints, fixings, and panel edges create thermal bridges that reduce effective insulation. Specify slightly above the calculated minimum to compensate.
- Assuming thicker is always better: Beyond a certain point, additional thickness adds cost and weight with diminishing thermal returns. Match thickness to the actual requirement.
- Neglecting acoustic performance: In noise-sensitive applications (offices near industrial areas, for example), acoustic performance may require a specific core type and thickness independent of thermal needs.
FAQ: How to Choose Sandwich Panel Thickness
Q: What thickness is most commonly used for commercial warehouse walls?
A: 100mm PIR or PUR core panels are the most common choice for commercial warehouse walls in moderate climates, offering a good balance of thermal performance, structural capacity, and cost.
Q: Can I use the same panel thickness for walls and roofs?
A: Not always. Roofs typically require better insulation than walls because heat loss through the roof is higher. A project using 75mm wall panels may need 100mm or 120mm roof panels to meet energy codes.
Q: How thick should sandwich panels be for a cold room?
A: A standard chilled room (0–5°C) typically uses 100–150mm panels. Freezer rooms (-18°C to -25°C) require 150–200mm. Deep-freeze applications below -30°C often need 200mm or more.
Q: Does thicker always mean better fire resistance?
A: Not directly. Fire resistance depends more on core material than thickness. Mineral wool cores provide the best fire resistance. PIR offers moderate fire performance. EPS performs poorly in fire and should be avoided where fire ratings are required.
Q: What is the lightest sandwich panel option for a given thickness?
A: PIR core panels are generally lighter than mineral wool panels at the same thickness, making them preferable where roof load or ease of installation is a concern.
Q: How does climate zone affect the recommended thickness?
A: Tropical climates with mild temperature differentials may only need 50–75mm for walls. Cold or temperate climates with significant heating or cooling loads typically require 100–150mm or more to meet energy codes.
Q: Is 50mm sandwich panel enough for an exterior wall?
A: In tropical or mild climates with low energy code requirements, 50mm may be sufficient for non-critical applications. In most commercial construction, 75–100mm is the practical minimum for exterior walls.
Q: How do I find out the minimum U-value required in my area?
A: Check the national or local building energy code, or consult a structural or energy engineer familiar with your region. Requirements vary significantly by country and climate zone.
Q: Does panel thickness affect sound insulation?
A: Yes, but core material matters more than thickness for acoustic performance. Mineral wool cores provide significantly better sound attenuation than foam cores at the same thickness.
Q: Where can I see available sandwich panel products and specifications?
A: The sandwich panel products page lists available thicknesses, core types, and technical specifications.
Conclusion
Knowing how to choose sandwich panel thickness correctly saves money, ensures code compliance, and delivers the thermal and structural performance a building needs over its lifetime. The process is straightforward when approached systematically: confirm the application, check local energy codes, select the right core material, calculate the required thickness, and verify structural and fire performance before ordering.
Actionable next steps:
- Obtain the energy code U-value requirements for your specific climate zone and building type.
- Request certified thermal and structural data sheets from your panel supplier for the core material you are considering.
- Use the thickness selection table in this guide as a starting point, then refine based on your specific load and span requirements.
- Compare at least two thickness options on total project cost, including long-term energy savings, not just upfront material cost.
- Work with an experienced sandwich panel manufacturer who can provide project-specific technical support and certified test data.
Getting the thickness right at the specification stage is far less expensive than correcting it during or after construction.
References
- ASHRAE. (2022). ASHRAE 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings. American Society of Heating, Refrigerating and Air-Conditioning Engineers. https://www.ashrae.org/technical-resources/bookstore/standard-90-1
- European Commission. (2020). Energy Performance of Buildings Directive (EPBD). https://energy.ec.europa.eu/topics/energy-efficiency/energy-efficient-buildings/energy-performance-buildings-directive_en
- ECCS (European Convention for Constructional Steelwork). (2014). Preliminary European Recommendations for Sandwich Panels. https://www.steelconstruct.com