Fixing and buying guide

Who this product is for

This insulation is suitable for builders and contractors undertaking new build masonry cavity wall construction or retrofit cavity fill projects. It is specified where thermal performance, vapour control and moisture management must be integrated into a single product. Serious DIY customers with cavity wall projects may also use this product, provided they have appropriate access and fixing capability.

Sizing and pack contents

Each board measures 1200mm length by 450mm width and 90mm thickness. The 90mm depth is calculated to fill a standard masonry cavity whilst maintaining the essential 10mm residual air gap behind the board for moisture transfer and ventilation. Check your cavity width before ordering; this product is designed for cavities of approximately 100mm. Boards are supplied individually and must be ordered in quantities matching your wall area.

• Board dimensions: 1200mm × 450mm × 90mm
• Calculate coverage: multiply board length by width to find area per board
• Order sufficient boards to cover total cavity area plus 5% waste for cutting and fitting

Compatibility and installation preparation

The tongue and groove edge profile is integral to this product and ensures boards lock together without gaps, creating a continuous insulation layer. The aluminium foil facing acts as both a thermal reflector and vapour control layer, so no additional membrane is required. Before installation, ensure the cavity is clean and free from debris, mortar droppings and obstructions. The residual 10mm cavity must be maintained behind the boards to allow air circulation and moisture management; do not compress or force boards into oversized cavities. Boards should be fitted with the foil facing towards the inner leaf of the masonry.

• Cavity must be clean and free from mortar, debris and obstructions
• Maintain 10mm residual cavity behind boards for moisture control
• Tongue and groove edges must interlock fully to eliminate thermal bridging
• Aluminium foil facing provides vapour control; no additional membrane needed

Pre-installation checks

Verify cavity width is suitable for 90mm insulation with residual cavity space. Inspect the masonry cavity for structural soundness, dampness or active water ingress; if present, address the source before installing insulation. Confirm the inner and outer leaves are plumb and parallel to avoid forcing boards into uneven cavities. Check that cavity ties or wall ties are in place and properly spaced. Ensure you have appropriate access equipment and temporary support systems for safe board placement during installation. Store boards in dry conditions prior to fitting.

• Measure cavity width to confirm suitability for 90mm boards
• Inspect for dampness, water ingress or structural defects
• Verify cavity is plumb and parallel
• Confirm cavity ties are present and correctly spaced