Insulation Calculator
Enter the surface area and the board size to get boards, packs and cubic metres.
The formula
Boards = area × (1 + waste) ÷ area of one board. A 5% allowance covers cuts at corners, windows and rafters.
Worked example
A 90 m² facade with 1000 × 600 mm boards (0.6 m² each) and 5% waste: 94.5 ÷ 0.6 = 158 boards. At 6 boards per pack that is 27 packs.
Board sizes
| Material | Typical size, mm |
|---|---|
| Mineral wool boards | 1000 × 600, 1200 × 600 |
| EPS (expanded polystyrene) | 1000 × 1000, 1000 × 500 |
| XPS (extruded) | 1200 × 600 |
| Mineral wool rolls | 1200 wide, 5000–9000 long |
Two layers instead of one
Two layers with staggered joints work better than one thick layer, because the joints do not line up. Calculate each layer separately — just run the calculator twice.
What else you will need
For a facade: 5–8 plate fixings per m² (the fixing pattern sets the exact number), 5–6 kg/m² of adhesive for bonding plus 4–5 kg/m² for the reinforcing coat, and mesh with 10 cm overlaps. For a roof: vapour and windproof membranes over the same area plus overlaps.
The insulation thickness comes from a thermal calculation for your climate and wall build-up, not from what the neighbours used.
Construction Material Calculators
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