Loft Conversion Cost Calculator UK

Get an indicative cost range for your loft conversion project. Choose the conversion type, size, specification and location for a UK market estimate.

Box dormer to rear, adds full head height.

Additional Options

Estimated Loft Conversion Cost

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Indicative range. Not a quote. Includes a 10% contingency.

Cost Breakdown

Structural Works
Staircase
Plumbing & Electrical
Admin & Permissions
Contingency (10%)
Estimated Total
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How We Estimate

  • Estimates assume a standard UK semi-detached or terraced property. Flats and end-terrace properties may have different structural requirements.
  • Prices include design, structural engineer, building control and all trades.
  • Loft conversions typically require Building Regulations approval even under Permitted Development.
  • This is an indicative estimate, not a quote.
  • Last updated: Q2 2026.