How and where to use guide
Rigid PIR Insulation 1200 x 2400 x 25mm
Typical applications
This 25mm board is suited to cavity wall insulation, suspended timber floor insulation, pitched roof rafter spaces, and flat roof applications. The thickness makes it particularly useful where building depth is constrained, such as in retrofit projects with existing structural elements, or as part of a multi-layer insulation build-up. The compressive strength of 175 kPa supports typical residential and light commercial loading in floor and roof applications.
- Cavity wall insulation between masonry leaves
- Suspended timber floor insulation between joists
- Pitched roof insulation between rafters
- Flat roof insulation in warm roof construction
- Layered insulation systems where combined thickness is required
Installation and handling
The 1200 x 2400mm sheet size is designed for straightforward handling and installation by trade and serious DIY users. Boards should be cut to fit cavity widths, joist or rafter spacings using a fine-toothed saw or hot-wire cutter. Ensure boards are fitted snugly between structural elements to minimise air gaps and thermal bridging. In cavity walls, boards are typically held in place with cavity wall ties or friction fit. In floor and roof applications, boards should be supported fully on the structural base or between joists. Always follow the specific installation guidance provided by the board manufacturer, as application methods may vary slightly between brands.
- Measure cavity or joist spacing accurately before cutting
- Use a fine-toothed saw or hot-wire cutter for clean cuts
- Fit boards snugly to minimise air gaps and thermal bridging
- Ensure full support on structural base in floor and roof applications
- Refer to manufacturer installation instructions for brand-specific guidance
Limitations and site considerations
At 25mm thickness, this board is not intended as a standalone insulation solution for most applications; it is typically used as part of a layered approach or in space-constrained situations. PIR foam is combustible and must be protected with appropriate fire barriers or membranes as required by building regulations; do not leave boards exposed internally. The board should not be used in direct contact with bituminous materials or certain solvents, which can degrade the foam. Protect boards from weather and site damage during storage and installation. Compressive strength of 175 kPa is adequate for typical residential loading but should be verified for heavy-load applications such as commercial floors.
- Not suitable as sole insulation layer in most applications
- Must be protected with fire barriers or membranes to meet building regulations
- Avoid contact with bituminous materials and incompatible solvents
- Protect from weather and site damage during storage
- Verify compressive strength adequacy for heavy-load or commercial applications
Maintenance and durability
Once installed and properly protected, rigid PIR insulation requires no routine maintenance. The material is stable and does not settle or degrade under normal building conditions. Ensure that any exposed edges or cut surfaces are protected from moisture ingress and UV exposure during the construction phase. Once the building envelope is complete and the board is enclosed within walls, floors or roofs, the insulation will perform consistently throughout the building's life. BBA certification provides assurance of long-term performance and compliance with building standards.
- No routine maintenance required once installed
- Protect cut edges and exposed surfaces from moisture and UV during construction
- Ensure adequate ventilation in roof spaces to prevent moisture accumulation
- BBA certification confirms durability and building regulation compliance