IGU Spacer Systems Explained: Choosing the Right Spacer for Performance, Shape, and Size

At Tough Glass, we use three primary spacer systems across our IGU range: TPS (Thermoplastic Spacer), Super Spacer, and Aluminium Spacer Bars. Each offers distinct advantages depending on the project requirements, glass configuration, and unit design.

Understanding where each spacer excels helps ensure the right balance of performance, manufacturability, and long-term durability.

TPS (Thermoplastic Spacer): Our Primary Spacer System

TPS, or Thermoplastic Spacer, is the spacer system used on our automated TPA production line and is the most commonly specified spacer across our IGU range.

As a warm edge spacer technology, TPS is designed to minimise heat transfer between the interior and exterior of a building, helping improve the overall thermal efficiency of the glazing system. Manufactured from a thermoplastic material, typically based on polypropylene and similar polymers, TPS delivers excellent thermal performance while maintaining strong structural integrity.

One of the key advantages of TPS is its ability to form a continuous, airtight seal with no corner joins or gaps. This significantly improves gas retention compared with traditional spacer systems, helping preserve the long-term performance of the IGU.

Benefits of TPS

• Excellent thermal performance through warm edge technology
• Superior gas retention due to its continuous seal
• Reduced risk of air leakage through spacer joins
• Strong structural integrity and long-term durability
• Consistent manufacturing quality through automated production

Shape Limitations

TPS can be used for the vast majority of standard IGU shapes, including many custom configurations. However, because the spacer is applied via our TPA line, there are some limitations:

• At least one edge must be straight
• Internal angles cannot be smaller than 31 degrees
• Template-shaped units cannot be processed on the TPA line

Importantly, these limitations do not mean the unit cannot be manufactured. They simply mean an alternative spacer system may be required to achieve the desired shape.

Super Spacer: Maximum Flexibility for Complex Shapes

Before the introduction of TPS, Super Spacer was our primary warm edge spacer system. Today, it remains an essential solution for specialised and complex IGU configurations.

Unlike traditional metal spacer bars, Super Spacer uses a flexible silicone foam construction. This dramatically reduces thermal conductivity while allowing the spacer to adapt to complex shapes and geometries that rigid systems cannot accommodate.

Its flexibility also allows it to absorb the natural expansion and contraction of glass caused by temperature fluctuations, helping reduce stress on the edge seal and minimise the risk of gas leakage over time.

Benefits of Super Spacer

• Warm edge thermal performance
• Excellent resistance to thermal movement
• Reduced risk of seal failure
• Improved condensation resistance
• Suitable for highly customised shapes

Typical Applications

Super Spacer is often selected for:

• Dog door cut-outs
• Template shapes
• Complex geometric designs
• Curved and irregular IGUs
• Shapes that cannot be processed on the TPA line

When a design falls outside the manufacturing parameters of TPS, Super Spacer provides a proven alternative without compromising thermal performance.

Aluminium Spacer: The Traditional Solution for Oversized Units

Aluminium spacer bars have been used in double glazing for decades and remain a practical solution for certain specialised applications.

Compared with warm edge technologies such as TPS and Super Spacer, aluminium has significantly higher thermal conductivity. This means more heat can transfer through the edge of the IGU, resulting in lower thermal performance and potentially increased condensation around the perimeter of the glass.

For this reason, aluminium spacers are far less common in modern energy-efficient glazing systems.

Benefits of Aluminium Spacers

While thermal performance is lower, aluminium spacers still offer advantages in specific applications:

• High structural rigidity
• Proven long-term durability
• Suitable for large-format glazing
• Cost-effective in certain configurations

Typical Applications

At Tough Glass, aluminium spacers are primarily used in oversized IGUs, where additional structural stability is required.

These units are typically combined with a silicone secondary sealant to provide the strength and durability needed for large glass panels and demanding applications.

Spacer and Secondary Sealant Compatibility

Selecting the correct secondary sealant is just as important as selecting the spacer itself. Not all spacer systems are compatible with every sealant type. This is what Tough Glass can offer.

Tough Glass Standard IGU Configuration

Unless otherwise specified, Tough Glass will manufacture IGUs using TPS (Thermoplastic Spacer) with a polysulphide secondary sealant.

This combination provides an excellent balance of thermal performance, gas retention, durability, and manufacturing efficiency, making it suitable for the majority of standard IGU applications.

Alternative spacer and sealant combinations are available where project requirements, unit size, shape, or performance specifications require a different configuration.

Choosing the Right Spacer

There is no single spacer system that suits every application.

TPS delivers the best combination of thermal performance, gas retention, and manufacturing efficiency for most standard IGUs. Super Spacer provides the flexibility required for complex and irregular shapes, while aluminium spacers remain the preferred solution for certain oversized units where structural considerations take priority.

The right choice ultimately depends on the size, shape, performance requirements, and manufacturing constraints of the project.

By offering multiple spacer technologies, Tough Glass can match the spacer system to the application rather than forcing the application to fit a single manufacturing process.

Need Help Specifying an IGU?

Our team works with glaziers, fabricators, builders, and specifiers every day to determine the most suitable IGU configuration for each project. If you're unsure which spacer system is right for your application, contact the Tough Glass team for technical guidance and specification support.