Rigid Insulation Board
Rigid insulation boards (PIR/PUR foam boards such as Celotex or Kingspan) are high-performance panels fitted between and below the rafters in loft conversions. They offer excellent thermal resistance per unit thickness and provide a flat, stable surface for plasterboard to be fixed to. Rigid board is the industry standard for insulating the sloping ceiling of a converted loft and is straightforward to cut and fit around structural timbers.
Why Choose Rigid Insulation Board?
- High thermal performance — meets Building Regulations at 100–120mm thickness
- Creates a flat surface ready for plasterboard fixing
- Lightweight and easy to handle during installation
- Moisture-resistant closed-cell structure
- Compatible with all loft conversion types
Frequently Asked Questions
What thickness of rigid board do I need?
For a loft conversion meeting current Building Regulations (U-value of 0.18 W/m²K or better), you typically need 100–120mm of PIR board between the rafters, plus a continuous layer below. The exact specification depends on your rafter depth and chosen product. We calculate the correct build-up for your property.
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