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Nour Nagy Designs

Insulation Volume Calculator – Walls, Floors & Roofs

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Estimate how much insulation your project needs and how many packs to order. Enter the application, material, dimensions and number of layers, and the calculator returns area, volume, unit and pack counts, plus fixings and adhesive.

How to use

  1. Choose the application — wall, floor or roof.
  2. Select the material and board or roll thickness.
  3. Enter the dimensions of the area being insulated.
  4. Set the number of layers if you are cross-boarding.
  5. Add a wastage allowance and read the pack count.

Notes

  • Cross-boarding in two layers with staggered joints reduces thermal bridging at the joints compared with a single thick layer.
  • Rigid boards produce more offcut waste than rolls. Allow 10% on boards, 5% on rolls.
  • Mechanical fixing rates vary by substrate and board type. Treat the fixing count as indicative and check the manufacturer’s fixing pattern.
  • Full fill, partial fill and cavity clearance requirements differ — confirm which system you are using before ordering.

FAQs

How much insulation do I need for a loft?

Current UK guidance is around 270mm of mineral wool at ceiling level, usually laid in two crossed layers. If the loft is being converted to a habitable room, the insulation moves to the rafter line and a different build-up applies.

Rolls or rigid boards?

Rolls are cheaper and suit open joists and studwork. Rigid PIR boards give a better U-value per millimetre, so they win where depth is tight — floors, rafter lines and internal wall linings.

Does insulation thickness alone determine performance?

No. Thickness matters, but so does the material’s lambda value and, above all, the continuity of the layer. A well-installed thinner layer with no gaps often outperforms a thicker one full of gaps.

Need more than an estimate?

These tools give you a reliable starting figure. When you’re ready to turn it into a costed, fixed-scope proposal, our team works across London, Dubai and Cairo on architecture, interior design and turnkey delivery.

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