PolyFoam XPS Polyfoam Roofboard Extra - 1250mm x 600mm

• Excellent thermal performance
• 15mm lap joint
• High compressive strength
• Highly resistant to water absorption
• Able to resist repeated freeze/thaw cycles
• Lightweight and easy to install
• Tough and durable, not easily damaged
• Dimensionally stable
• Thermal performance of an inverted roof is improved when used in conjunction with ‎Polyfoam Slimlin zero Membrane

PolyFoam XPS Polyfoam Roofboard Extra – 1250mm x 600mm is best suited for use in inverted flat roof applications where high-performance thermal insulation and long-term durability are required. It performs exceptionally well below ballast or paving slabs, providing excellent compressive strength, dimensional stability, and resistance to moisture ingress, ensuring the roof structure remains thermally efficient over time. The board is also ideal for use in green or garden roofs, where it supports load-bearing vegetation layers while maintaining its insulating properties and resisting water absorption. Its closed-cell extruded polystyrene construction makes Polyfoam Roofboard Extra a reliable solution for demanding roofing environments that require both insulation and structural performance.

How does Roofboard Extra compare to the standard Polyfoam board?

The “Extra” grade typically offers higher strength, potentially lower moisture absorption or improved performance in demanding applications vs the “standard” grade. It is more appropriate for roof or more exposed applications where performance margins need to be higher.

What are limitations / cautions?

• Temperature: subject to limits (e.g. above certain temperatures XPS may soften)
• Fire performance: XPS is combustible; requires appropriate fire barriers or coverings in many roof or roof edge details
• Joints and detailing are critical to avoid thermal bridging or water ingress paths
• Must be protected during construction from mechanical damage, UV exposure, or accidental puncture

How is it installed (best practice)?

• Substrate should be clean, level, and prepared as per design requirements
• Boards should be tightly butted (no gaps)
• If multiple layers are used, stagger joints to avoid alignment
• Lay over the roof waterproofing membrane (in inverted roof design) and cover with ballast or protection as required
• Protect from prolonged exposure to sunlight (UV) and damage during installation
• Seal joints or edges if required by the system (e.g., using tapes, adhesives, or edge detailing)