The Ultimate Guide to Choosing PU Insulated Panel

Insulated metal panels, also commonly known as IMPs, are popular within many applications and industries for cold storage warehouses. With varying insulated metal panel types to choose from, each with its own advantages and disadvantages, it is crucial to identify your project requirements to select the best insulated metal panel for your project. To compare insulated metal panels, one must take multiple factors into consideration.  

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In this blog we explain the different types of insulated metal panels, their advantages and disadvantages and a comparison to help you make an informed decision about what IMP panel is best for your project.

Insulated metal panels or IMPs are versatile insulated building panels used in a wide range of industries to meet the need of many applications, often being used for refrigerated warehouses. 

IMPs are manufactured with two steel skins that sandwich an insulated core made from either expanded polystyrene, polyurethane or mineral wool.  

IMPs are used in interior and exterior applications as they are versatile and can serve various projects. Insulated metal panels can span further than framed panels making them more suitable for large scale applications such as refrigerated warehouses, food processing and large-scale controlled temperature facilities. 

These panels are manufactured in a range of thicknesses to meet the need of cold storage project specifications ranging from 2” to 10”.  

EPS cores can span longer distance without structural support compared to other metal panels making them a smart choice for interior applications such as: 

• Horticulture Rooms
• Clean Rooms
• Plasma Banks
• Controlled Environments

• Distribution Warehouses
• Food Processing Facilities

Polyurethane IMPs are manufactured with a steel skin and a Class 1 Urethane core. They are well-suited for exterior/interior walls and ceiling applications. The lightly corrugated profile on both faces creates symmetry on the outside of the building and room to room within. The minor rib provides a flattened appearance.  

Polyurethane Insulated Metal Panels are ideal for cold storage, commercial, scientific, and industrial applications. Insulated metal panels are not prefabricated to exact dimensions therefore cuts in the field are required and will increase installation cost.

Cam-Lock Polyurethane Insulated Panel systems may not be considered an IMP however they are used similarly in cold storage, warehouse, and large-scale applications. 

Cam-Lock insulated panels are manufactured with wood-framed or polyurethane framed and filled with poured-in-place polyurethane foam resulting in a higher R-value than traditional IMPs.  

Cam-Lock panels are designed with exact dimensions to meet project requirements with tongue and groove frames that allow for fast on-site assembly.  

While Cam-Lock panels require a higher investment upfront, the ease of installation, R-value, and customization options available make these a smart choice for a wide range of projects.

Below is a breakdown of the three primary types of insulated panels in our industry including EPS, IMP and Cam-Lock panels. It is important to identify the application that best fits the project specifications required. 

As shown in the insulated panel comparison chart below, it is important to consider the different variables including R-value, span length and applications of each insulated panel type when analyzing options.  

What Is A PU Sandwich Panel?

A PU Sandwich Panel is a sandwich-structured composite made of polyurethane foam sandwiched between two side skins:

Polyurethane core (PU/PUR)

Polyurethane insulation core is typically produced by the reaction of an isocyanate with a polyol, the PU foam board acts as a thermal barrier and ensures low thermal conductivity and excellent resistance to moisture, humidity, and other environmental factors.

Skin layers

PU sandwich panel consisting of an upper and inner layer made of galvanized steel sheets, PPGI (pre-painted galvanized iron), PPGL (pre-painted galvalume iron, coated by a hot dip zinc substrate), Prepainted steel, Stainless steel plates, Aluminium plate, Fiberglass skin, Fibreglass Reinforced sheet (FRP), CFRT sheet, Plywood, embedded wood, etc. The two skin layers are glued to the PU insulation core using polyurethane resin glue.

Why Choose PU Sandwich Panels?

PU sandwich panels have become essential for multiple commercial and industrial applications where a combination of high structural rigidity, low weight, and insulation performance is required, these characteristics make them preferred for various industries ranging from construction to cold rooms, cold storage, and cold chain. Moreover, these cost-effective PU insulated sandwich panels are popular for a variety of uses including insulated walls, partitions, claddings, roofs, floors, and building envelopes. Besides this, PU sandwich panels are highly resistant to moisture, mold, mildew, bacteria, and other environmental factors such as humidity, temperature variations, abrasion, and corrosion.

What PU Sandwich Panels Are Used For?

PU sandwich panel is an excellent choice for a wide range of applications including interior or exterior walls, partitions, ceilings, roofs, cladding, floors, and doors, these structural panels are most commonly used for the architecture, engineering and construction industry (AEC):

Prefabricated Buildings

Single and multi-story buildings

Prefabricated houses and shelters

Prefabricated buildings

Prefab buildings

Portable cabins

Airplane hangars

Buildings and construction

Residential complexes

Commercial facilities

Office buildings

Shopping centres

Clinics and health care centers

Schools and universities

Stadiums and sports facilities

Multi-purpose halls

Agricultural buildings

Steel agriculture buildings

Metal farms buildings

Agricultural storage buildings

Insulated livestock farms

Barns and poultry sheds

Crops and commodity storage structure

Harvesting equipment stores

Temperature Controlled Environment

Controlled environmental room

Clean rooms/Cold rooms

Cold storage facilities

Ripening chambers

CA chambers

Refrigerated Units

Walk-in refrigeration units

Refrigeration and freezing room

Negative temperature cold rooms

Temperature-sensitive storage

Temperature controlled warehouse

Applications in Trucks

Insulated box trucks

Refrigerated/van trucks

Refrigerated cargo/van

Vehicles with refrigerated body

Freezer trucks/trailer

Chiller lorry

RVs

Caravans

Travel Trailers

Motor homes

What Are The Components Of PU Sandwich Panels?

PU sandwich panel is a factory pre-engineered system, each unit consists of three layers that are strongly bonded with an adhesive (Polyurethane resin glue).

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Polyurethane Insulation (PU/PUR)

Polyurethane insulation offers a thermal conductivity ranging from 0,022 to 0,024 W/(m*K), and an R-value between 6.0 and 7.14 in, thanks to the polyurethane foam structure which contains 90% of rigid closed-cell and has a density core of 32 – 60 Kg per m3. Polyurethane foam is available in different sizes and thicknesses that suit all applications, it is also highly resistant to water, moisture and the elements.

Skin Layers

The two side facings consist of upper and lower layers, both of the skin layers are made from high-strength metal or non-metal material such as:

PPGI (Pre-painted Galvanized iron)

PPGL (Pre-painted Galvalume iron)

Galvanized steel sheets

Pre-painted steel sheets

Stainless steel sheets

Aluminum plate

Glass Reinforced Plastic (GRP)

Fiberglass Reinforced Polymer (FRP)

Plywood or Oriented Strand Board (OSB)

Protective coating

Metal skin layers can be protected using different types of coatings such as:

Polyester (PE)

SP Polyester 25 μm

SP Polyester Mat Pearl 35 μm

Food Safe PVC

Aluzinc + Easyfilm,

Polyvinyl chloride (PVC) coating

Polyvinylidene fluoride (PVDF)

Silicone modified polyester (SMP)

High durability polyester (HDP)

What Are The Characteristics Of Polyurethane Sandwich Panels?

PU sandwich panels are widely used to build the most sophisticated commercial and industrial facilities, thanks to the extremely durable material which offers unmatched benefits, we summarized some of them:

Thermal insulation

PU sandwich panels offer an excellent thermal conductivity (lambda λ) of 0.022 (W/mK), this coefficient is unparalleled by any other insulation material like EPS (Expanded Polystyrene) and Mineral Wool (MW), thanks to the PU system core which provides superior thermal insulation while it minimizes heat transfer across the whole building envelopes including walls, partitions, facades, ceilings, roofs and floors. Furthermore, Polyurethane (PU) sandwich panels have an average R-value of 6.5 per inch of thickness, the R-value (W/m²K) is normally determined by the thickness of the polyurethane foam (PU), the higher the R-value the better is the thermal resistance of the PU sandwich panel and the more it resists the conductive flow of heat.

Air-tightness

one of the most important features of polyurethane sandwich panels is their excellent insulation properties and airtight structure, which resists air, water, vapor ingress, and moisture, each structural insulated panel (SIP) comes with a tongue and groove joints sealed with white or transparent sealants, the sealing is applied to avoid air infiltrations and leakage of heat or cooling energy through the building envelope, this enhances energy-efficiency and substantially lower the energy spend for heating in the winter and cooling in the summer, which minimize energy costs over the long run while it maintains a consistent temperature inside the building and provide comfort.

What Are The Types Of PU Sandwich Panels?

PU sandwich panels are highly versatile, architects and builders can choose from a variety of attractive features that include a wide range of shapes, profiling patterns, colours, finishes, protection coatings, and endless customization options, this allows them to achieve the greatest benefits at the lowest cost. The most commonly used PU sandwich panels are as follows:

PU Wall Sandwich Panels

PU Roof Sandwich Panels

PU Floor Sandwich Panels

PU Sandwich Panels for Duct Board

HVAC Air Duct PU Sandwich Panels

Insulated Air Ducts (Polyurethane Insulation Panel)

PU Sandwich Panels for Cold Rooms

PU Sandwich Panels for Cold Storage

Fireproof PU Sandwich Panels

Also, PU sandwich panels come with different types of fixing and joints:

Secret Fix Panels

Hidden screw sandwich panel

Boltless sandwich panel

Hidden joint sandwich panel

What Sizes Are PU Sandwich Panels?

Polyurethane sandwich panels can be manufactured in a variety of sizes; the following are the standard sizes available on the sandwich panels market, while custom sizes can be also provided:

Interior and Exterior skin: 0.5 – 0.8 mm steel sheet

Width: 500 - (mm)

Length: 2.0 – 24 (m)

Thickness: 40, 60, 75, 100, 125, 150, 170, 200 (mm)

PU Wall Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120, 150, 170, 200 mm

PU Roof Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120 mm

PU Cold Room Sandwich Panel: 120, 150, 170, 200 mm

PU Duct Panel Sandwich Panel: 20, 30 mm

What Is The Length Of PU Sandwich Panels?

The length of the PU sandwich panel depends mainly on the application requirements; the standard length of PU sandwich panels varies between 2 – 16 mts, and up to 22 meters long. Also, PU sandwich panels can be custom-sized to a specific length.

What Is The Weight Of PU Sandwich Panels?

The weight of the PU sandwich panel is determined by the thickness of the skin and the density of PU foam and size. On average, PU sandwich panels’ weight ranges between 10 and 20 (kg/m2), however, most PU sandwich panels come on the following weight (kg/m2):

Thickness: 40 mm, weight (kg/m2): 10

Thickness: 80 mm, weight (kg/m2): 12

Thickness: 140 mm, weight (kg/m2): 14

Thickness: 200 mm, weight (kg/m2): 17

What Is the Production Process Of PU Sandwich Panels?

A PU sandwich panel typically consists of two elements: a polyurethane insulation core and two metal sheets (skin layers), these components are produced as follows:

Polyurethane Core

Polyurethane panels (PU-PUR) foam production starts by mixing the required chemicals which are metered and dosed together in a polyurethane foaming system like “PU Foaming Machine” or “Metering Machine”, the mixture results in creating a liquid which is distributed over the metal skin layer (rigid metal facing material).

Skin Layers

The skin layers or metal sheets could be PPGI (pre-painted galvanized iron), PPGL (pre-painted Galvalume iron), and Aluminum sheets, these skin layers are formed or grooved with a roll forming machine (metal roll forming machine) which is used to produce flat metallic sheets when mass-production is required. Also, rigid metal facings can be coated by metallic substrate, hot dip zinc substrate or color coated.

How PU Sandwich Panels Are Manufactured?

Polyurethane (PU) sandwich panels are manufactured using continuous or discontinuous production lines:

Continuous Polyurethane Sandwich Panel Line

All the materials are processed together and operated continuously, the process includes an automatic feeding of raw materials, and passes by the roll forming system, after that, the formed panels are finished and cut to the desired lengths without stopping the production line. The continuous PU sandwich panel line comes with an advanced automation system that ensures high-volume manufacturing, and high speed which is 10 times more than the discontinuous PU sandwich panel line, it can also produce 12 meters per minute double press and achieve a production capacity of about 1,180,000 meters per year.

Discontinuous Polyurethane Sandwich Panel Line

In a discontinuous process, the materials are processed separately, while the facings sheets are formed and cut to the desired length, after that, all the components are joined together in a press where the foam is injected. Cutting-edge manufacturing equipment is used to customize PU sandwich panels and create special shapes. The discontinuous polyurethane sandwich panel line is used to produce a small volume of PU sandwich panels as it has limited production capacity and cannot be compared with that of the continuous sandwich panel production line.

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