How and where to use guide

Rigid PIR Insulation 1200 x 2400 x 90mm

Typical applications and installation

These PIR boards are designed for use in cavity wall insulation, floor insulation between joists or over concrete slabs, and roof insulation in pitched or flat roof constructions. In new build work, boards are typically fitted between structural elements and secured with mechanical fixings or adhesive according to building control requirements and manufacturer guidance. In refurbishment and retrofit projects, boards can be installed internally or externally depending on wall construction and moisture management strategy. Always check that the installation method and vapour control layer specification comply with current Building Regulations and the specific brand manufacturer's technical guidance.

Cavity walls: fit between inner and outer leaves, securing with wall ties or cavity closers as required
Suspended timber floors: lay between joists, supporting with battens or netting to prevent sagging
Concrete floors: lay directly on slab with appropriate damp-proof membrane below
Pitched roofs: install between rafters or over rafters depending on roof design and ventilation requirements
Flat roofs: use as part of warm roof or inverted roof system with appropriate weatherproofing layer above

Handling and on-site storage

The lightweight rigid foam construction makes these boards easier to handle than mineral wool alternatives, reducing fatigue and speeding installation. Store boards flat and dry on site, protected from weather and direct sunlight. Stack boards carefully to avoid crushing lower boards under excessive weight. Keep boards away from heat sources and naked flames, as PIR is a combustible material. Ensure adequate access and working space around the installation area to allow safe handling of the full 1200 x 2400mm sheet size.

Store flat on level ground or pallets, not leaning against walls
Protect from rain and moisture during storage and installation
Keep away from direct sunlight to prevent material degradation
Ensure two-person handling for safe board placement
Plan delivery and storage location before materials arrive on site

Cutting and fitting

PIR boards can be cut to size using a sharp handsaw, circular saw or hot wire cutter, depending on the precision required and site conditions. Measure twice before cutting to minimise waste. Fit boards tightly together to reduce thermal bridging through gaps; use expanding foam or backer rod to seal any unavoidable gaps between boards and around service penetrations. The 90mm thickness is designed to fit standard timber frame spacings and cavity widths, reducing the need for additional packing or tapered cuts.

Use sharp tools to achieve clean cuts and reduce dust generation
Wear appropriate PPE including gloves and dust mask when cutting
Seal gaps between boards with expanding foam or backer rod to maintain thermal performance
Fit boards snugly to structural elements to prevent movement and air leakage
Plan board layout to minimise cutting and waste

Performance and maintenance

The 0.022 W/mK thermal conductivity ensures consistent insulation performance throughout the board's service life. PIR boards do not absorb moisture or settle like mineral wool, maintaining their thermal resistance over time. Once installed and protected by appropriate finishes or membranes, boards require no ongoing maintenance. Ensure that any exposed edges are protected from UV damage and that the installation includes appropriate fire safety measures such as fire barriers or board coverings as required by Building Regulations for the specific application.

Thermal performance remains stable and does not degrade with age
No settling or compression under normal building loads due to 175 kPa compressive strength
Protect exposed edges from UV exposure and weather
Ensure fire safety compliance with appropriate board coverings or barriers where required
Check that vapour control layers and moisture management are correctly specified for your application