Polystyrene Insulation Board

What Is Polystyrene Insulation?

Polystyrene insulation, while commonly used, has limitations in its insulating properties compared to some other materials. It is primarily available in two forms: expanded polystyrene (EPS) and extruded polystyrene (XPS).

EPS is lightweight and cost-effective, but its insulating capabilities are modest compared to other materials. It's often used in situations where moderate insulation is acceptable, such as in packaging or construction applications where cost is a primary concern.

XPS, on the other hand, offers slightly better insulation performance than EPS due to its denser, closed-cell structure. However, it still falls short of the thermal performance provided by materials like rigid foam boards or spray foam insulation.

Both EPS and XPS are relatively easy to work with and provide some degree of thermal resistance. However, it's essential to consider their limitations when selecting insulation materials for a project. In applications where high levels of insulation are required, such as in energy-efficient construction or in extreme climates, alternative insulation materials may be more suitable.

Where Can You Use Polystyrene Insulation?

• Wall Systems: Both external and internal walls can be insulated with polystyrene to reduce heat transfer.
• Flooring: Polystyrene insulation boards are often laid below floor surfaces to provide thermal comfort and reduce heat loss.
• Roofing: Suitable for both flat and pitched roofs, these insulation boards can be applied directly beneath the roof covering.
• Basements and Foundations: Their resistance to moisture makes them ideal for insulating basements and crawl spaces.

Types of Polystyrene Insulation

Polystyrene foam insulation comes in two main varieties:

• Expanded Polystyrene (EPS): This type is lighter and is often used for wall insulation, floor slabs, and foundation systems.
• Extruded Polystyrene (XPS): Denser and more water-resistant than EPS, XPS is often chosen for roofing and for insulating areas that might come in contact with moisture.

To greater understand the difference between both of these materials, take a look at our comprehensive blog on the Differences Between XPS and EPS. 

Expanded Polystyrene Insulation

When compared to other rigid insulations, Expanded Polystyrene Insulation Board (otherwise known as EPS) is, without doubt, the most cost-effective. This is due to the fact that it is less dense and cheaper than XPS as it is less thermally effective.

Unlike XPS, EPS is not a closed-cell insulation board (whilst it has a closed-cell structure) meaning it allows water vapour/moisture to penetrate over time.

Despite its performative inferiority to more premium brands of thermal insulation, EPS exhibits consistent thermal performance in an extensive range of building insulation applications such as floor, wall and loft applications.

Not only do they possess high load-bearing capacity but they are also moisture resistant and unaffected by bacteria, moulds and fungi.

EPS insulation is predominantly used as floor insulation and in external wall insulation systems. Most people invest in Jablite insulation boards when they want to reduce the amount of heat they lose through their floorboards or floor tiles.

EPS insulation is available in a range of thicknesses from 25mm to 100mm, which makes it suitable for a range of insulation projects. 

Extruded Polystyrene Insulation

Extruded polystyrene insulation (often referred to as XPS) is manufactured, as the name would suggest, through an extrusion process. Kingspan is the main manufacturer of this insulation in the UK. Extruded polystyrene insulation (XPS) is manufactured using a process of extrusion. 

This process results in a closed-cell structure that boasts smooth, dense skin on both faces. The closed-cell structure of extruded polystyrene (XPS) prevents water penetration, thus providing long-term strength and durability.

Kingspan GreenGuard boards have a thermal conductivity of 0.034 W/mK. As such, XPS foam is marginally more effective than EPS foam as a thermal insulator. 

It is tough when it comes to insulation yet gentle when it comes to the environment, as the blowing agent used to manufacture it has zero ODP (Ozone Depletion Potential) and low global warming impact.

GreenGuard insulation is high-performing in its versatility and can be installed in both residential and commercial properties. You can install Kingspan GreenGuard XPS foam in inverted roofs, basements, car parks, and even underneath industrial cold-flooring. 

GreenGuard foam boards have a compressive strength of 300 kPa, meaning these boards will not lose their thermal properties when placed under pressure. 

We stock a wide range of extruded polystyrene insulation thicknesses from 30mm to 120mm.

How to Cut Polystyrene Insulation Boards

• Prepare Your Workspace: Ensure you have a flat surface to work on and wear safety glasses.
• Measure and Mark: Use a straight edge and a marker to outline your desired measurements on the insulation board.
• Use a Sharp Knife: A utility knife or a hot wire cutter can be used. If using a knife, ensure it's sharp for cleaner cuts.
• Score and Snap: Gently score the board along the marked lines and then apply gentle pressure to snap it.
• Smooth Edges: Sand any rough edges for a clean finish.