Polystyrene Insulation

Polystyrene insulation is a key material in the UK construction industry. It stands out for its excellent thermal performance, cost-effectiveness, and lightweight structure. It is commonly used to insulate roofs, walls, ceilings, and floors in residential, commercial, and even industrial structures.

What Is Polystyrene Board?

Polystyrene board is a term used to refer to both extruded and expanded forms of polystyrene, i.e., XPS and EPS boards, respectively. Builders use them in roofing systems, wall cavities, external wall cladding, and under-slab applications.

Expanded Polystyrene (EPS) is manufactured by expanding beads inside a mould to create a lightweight structure. On the other hand, Extruded Polystyrene (XPS) is manufactured by extrusion, a process that makes it more uniform and moisture-resistant.

What Is A Polystyrene Sheet Used For?

It is commonly installed:

• Under concrete or timber floors
• Inside stud walls
• As part of external wall insulation systems
• Underneath pitched or flat roofs
• In heavy-duty floors using higher-density EPS or XPS grades designed for load-bearing

Types Of Polystyrene Insulation Sheets

Polystyrene insulating sheets are sold as:

Expanded Polystyrene (EPS)

EPS boards, such as Jablite, are typically white or grey (depending on the amount of added graphite) and have a compressive strength range of 70–300 kPa, depending on grade. It is primarily used for wall, roof, and general floor insulation. EPS sheets are lightweight and dimensionally stable under normal service conditions. However, they have lower impact and water resistance than XPS.

Extruded Polystyrene (XPS)

XPS is the more rigid blue or pink material with a smooth surface and tight, consistent internal structure. XPS boards have a compressive strength of 300–700 kPa and are suitable for heavier loads and flat roofs. XPS absorbs far less water than EPS and maintains its strength in damp conditions.

Benefits Of Polystyrene Boards

Builders and DIYers commonly use polystyrene boards because of these perks:

• They regulate indoor temperatures by slowing heat transfer.
• They are much lighter than solid materials and easier to carry, cut, and fit into position.
• XPS boards can support high loads without significant compression, which makes them suitable for floors and basements – in areas subject to heavy loads. Some XPS sheets, such as Kingspan GreenGuard, have compressive strength high enough for vehicle loads or car park decks.
• XPS offers superior water and moisture resistance; EPS board provides limited moisture resistance. This makes XPS suitable for damp environments and underground applications.
• Polystyrene sheets can be layered and used in many parts of a building – from floors and walls to roofs and even below-grade insulation.

FAQ

Where to buy polystyrene insulation?

Buy polystyrene insulation sheets online at Insulation Wholesale. Our UK stock includes Jablite and Kingspan GreenGuard boards in varying lengths, thicknesses, and compressive strengths. Request a fast quote and enjoy low wholesale prices, with nationwide UK delivery.

How to cut polystyrene insulation?

Measure, then mark where to cut. Score along the marked line, then cut using a sharp knife (or a hot-wire cutter or fine-tooth saw), using a straight edge as your guide. This is often the recommended method for rigid XPS boards.

How does polystyrene insulation work?

Polystyrene traps air, limiting heat movement through the foam, ensuring that warm air remains inside during winter and hot air outside during summer.

The boards are stable and maintain that “air-pocket and foam barrier” for many years under normal building conditions. In XPS boards, closed cells also repel moisture and prevent heat loss from water movement.

Can polystyrene be used as insulation?

Yes, EPS and XPS polystyrene provide excellent insulation for floors, walls, roofs, basements, and external wall build-ups. Each is chosen for its insulating power and ease of use, with XPS notably valued for its strength and water resistance.