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
FLFlorida Building Code
References & Sources
Standards Cited
- IECC — International Energy Conservation Code
Sets minimum insulation R-value requirements by climate zone that determine insulation thickness choices - ASTM C578 — ASTM C578: Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation
Defines standard rigid foam insulation board specifications and thermal performance
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 vary by manufacturer (e.g., Owens Corning, Dow, Rockwool); common sizes include 2x8 ft and 4x8 ft — ASTM C578 / manufacturer catalogues
- Common thickness range: 1"-2" for walls, 2"-6" for attics depending on climate zone — IECC
- Typical wastage allowance of 5-10% for cutting and fitting — Industry standard practice