Product Overview
Celotex Thermaclass Cavity Wall 21 Full Fill Insulation Board with a 115mm thickness and 1190mm × 450mm dimensions.
High-performance rigid polyisocyanurate (PIR) insulation board designed for use in full fill masonry cavity wall applications. Manufactured with a low emissivity foil facing, it delivers exceptional thermal conductivity of 0.021 W/mK, helping achieve low U-values while reducing overall wall thickness requirements.
The tongue and groove edge profile provides a tight, secure fit, minimising air gaps and thermal bridging. The board can be installed as a full fill solution or with a residual cavity of up to 10mm to accommodate mortar squeeze and simplify installation.
Lightweight, rigid, and easy to handle, the board fits standard wall tie spacing, supporting fast, efficient on-site fitting. The 115mm thickness is ideal for deeper cavity walls in high-performance housing and commercial developments.
Features & Benefits
- Outstanding thermal performance: Declared thermal conductivity of 0.021 W/mK reduces wall thickness while achieving low U-values.
- High performance facer: Low emissivity foil facing improves performance in cavities with up to 10mm air space.
- Precision fit: Tongue and groove edge detail ensures close jointing and minimal thermal bridging.
- Ease of installation: Sized for standard wall tie spacing; light, rigid boards are simple to transport and fit.
- Certified performance: BBA certified for full fill cavity wall use under Certificate 16/5343.
- Thickness: 115mm board ideal for deeper cavity walls in high-performance housing and commercial developments.
Applications
- Full fill cavity walls: Suitable for use between masonry leaves in domestic and commercial buildings.
- New build housing: Provides excellent U-value compliance in energy-efficient walls.
- Residual cavity installation: Can be fitted with a 10mm residual cavity to accommodate mortar squeeze.
- Thermal upgrade projects: Ideal for meeting advanced energy performance requirements.
Installation Guidance
- Preparation: Ensure cavity surfaces are clean and free from debris before installation.
- Board placement: Install boards with tongue and groove joints interlocked and staggered in brick bond pattern.
- Fixing method: Secure with appropriate retaining clips to wall ties as construction progresses.
- Joint sealing: Ensure tight-fitting joints with no gaps; seal edges as required by specification.
- Residual cavity: Maintain up to 10mm air space where design requires.
- Protection: Keep boards dry and covered until fully installed.
Compliance & Performance
- Material specification: Rigid PIR insulation with low emissivity foil facing.
- Thermal conductivity: 0.021 W/m·K (to BS EN 13165).
- Fire performance: Euroclass E reaction to fire to BS EN 13501-1.
- Compressive strength: ≥120 kPa at 10% compression.
- Water vapour resistance: High resistance due to foil facing.
- Certification: BBA certified (No. 16/5343) for full fill cavity wall systems.
- Environmental compliance: Manufactured under ISO 14001:2015 Environmental Management System.
- Standards compliance: UKCA marked to BS EN 13165 for factory-made rigid polyurethane (PU) insulation.
- Important note: Install and maintain in accordance with Celotex guidance and BBA certification details.