How and where to use guide
Mannok Isoshield Full Fill Cavity 1200mm x 450mm x 90mm (0.54m/sq)
Typical applications
Mannok Isoshield Full Fill Cavity is used in cavity wall construction to fill the cavity space between inner and outer leaves of masonry. It is particularly suited to new build projects and renovation work where achieving high thermal performance is essential to meet building regulations. The full cavity width utilisation means you can maximise insulation thickness without increasing overall wall dimensions, making it ideal for projects where external wall thickness is constrained.
- New build cavity wall insulation in domestic and light commercial properties
- Retrofit cavity wall insulation where cavity width is 90mm or greater
- Projects requiring U-values that exceed current building regulations
- Applications where maintaining wall weathertightness is critical
Installation and on-site handling
The boards measure 1200mm x 450mm x 90mm and are installed horizontally between the cavity leaves, with the tongue-and-groove edges interlocking to create a continuous thermal barrier. Each board covers 0.54 m². Begin installation at the base of the cavity and work upwards, ensuring boards are fully seated and joints are tight. The tongue-and-groove profile automatically aligns boards and eliminates gaps where moisture could penetrate. Boards are easy to cut on site using a fine-toothed saw if required to fit around openings or irregular cavity widths. Always wear appropriate PPE including gloves and a dust mask when cutting PIR foam.
- Install boards horizontally, starting from the base of the cavity
- Ensure tongue-and-groove edges are fully engaged to maintain insulation continuity
- Cut boards with a fine-toothed saw if necessary; support the board securely during cutting
- Do not compress or force boards into the cavity; they should sit naturally between leaves
- Wear gloves and dust mask when handling and cutting on site
Thermal performance and building regulations
The thermal conductivity of 0.022 W/mk combined with the low emissivity composite foil facings ensures maximum thermal resistance within the cavity. This specification delivers U-values that meet and exceed current building regulations for cavity wall construction. The foil facing reflects radiant heat, further improving the overall thermal performance of the wall assembly. Confirm cavity width before ordering to ensure 90mm thickness is appropriate for your application; boards must fit the full cavity width without being forced or compressed, as this would reduce thermal effectiveness.
- Thermal conductivity 0.022 W/mk provides high insulation value in a compact thickness
- Low emissivity foil facing maximises thermal resistance through radiant heat reflection
- Verify cavity width is suitable for 90mm board thickness before installation
- Do not compress boards; thermal performance depends on maintaining foam integrity
Moisture management and durability
The tongue-and-groove profiled edges and low emissivity composite foil facing work together to eliminate moisture ingress risk at board joints. The foil facing acts as a vapour control layer, protecting the PIR foam from moisture penetration. The cavity itself must remain clear and unobstructed to allow any residual moisture to drain downwards; do not block weep holes or cavity trays. Mannok Isoshield Full Fill Cavity boards are durable and require no ongoing maintenance once installed. The PIR foam and foil facing are stable in normal building conditions and will not degrade or settle over time.
- Tongue-and-groove joints prevent moisture ingress at board interfaces
- Foil facing provides vapour control and protects the foam core
- Ensure cavity remains clear and weep holes are unobstructed for drainage
- No maintenance required after installation; boards remain stable and effective indefinitely