Insulation Board Calculator
Calculate how many insulation boards you need for your floor, wall, or loft project. Supports PIR boards (Celotex, Kingspan), mineral wool, and other common insulation types.
When to Use
- Loft insulation - between or over joists
- Floor insulation - solid or suspended floors
- Wall insulation - internal or external walls
- Roof insulation - warm or cold roof setups
Common Board Sizes
| Type | Size | Coverage |
|---|---|---|
| PIR (Celotex/Kingspan) | 1200mm × 2400mm | 2.88 m² |
| Mineral Wool (Rockwool) | 600mm × 1200mm | 0.72 m² |
| Earthwool (Knauf) | 600mm × 1200mm | 0.72 m² |
Tips
- Allow 5-10% extra for cutting wastage
- For lofts, measure between joists if fitting between
- PIR boards provide better insulation per mm thickness
- Check building regulations for minimum U-values
UKUK Building Regulations
References & Sources
Standards Cited
- Building Regulations Approved Document L — Conservation of fuel and power
Sets minimum U-value requirements that determine insulation thickness choices (50-200mm) View → - BS EN 13162 — Thermal insulation products for buildings — Factory made mineral wool (MW) products
Defines standard mineral wool board sizes and thermal performance specifications
Formulas Used
- Board area:
boardAreaM2 = (boardWidth / 1000) x (boardLength / 1000)
Source: Basic geometry — Common sizes: 600x1200mm (0.72 m2), 1200x2400mm (2.88 m2) - Boards required:
boardsRequired = ceil(area / boardAreaM2)
Source: Standard quantity calculation - Boards with wastage:
boardsWithWastage = ceil(boardsRequired x (1 + wastage/100))
Source: Industry standard practice
Key Assumptions
- Standard board sizes: 600x1200mm for lofts, 1200x2400mm for floors/walls — BS EN 13162 / manufacturer catalogues (Celotex, Kingspan, Knauf, Rockwool)
- Common thickness range: 50-100mm for internal walls, 100-200mm for lofts — Building Regulations Approved Document L
- Typical wastage allowance of 5-10% for cutting and fitting — Industry standard practice