How Much Does Loft Conversion Cost in 2025?
Last updated: February 2026
Average cost in United Kingdom
Typical average: £35,000
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Loft Conversion Cost by Country
| Country | Low | Average | High |
|---|---|---|---|
| 🇬🇧United Kingdom | £20,000 | £35,000 | £50,000 |
| 🇺🇸United States | $40,000 | $60,000 | $80,000 |
| 🇦🇺Australia | A$50,000 | A$75,000 | A$100,000 |
| 🇨🇦Canada | C$50,000 | C$70,000 | C$90,000 |
Loft Conversion Cost Breakdown
| Item | 🇬🇧 UK | 🇺🇸 US |
|---|---|---|
| Velux/rooflight conversion | £20,000-30,000 | $35,000-50,000 |
| Dormer conversion | £35,000-50,000 | $50,000-75,000 |
| Hip-to-gable | £45,000-60,000 | $60,000-85,000 |
| Mansard conversion | £50,000-75,000 | $70,000-100,000 |
| En-suite bathroom | +£4,000-8,000 | +$8,000-15,000 |
What Affects Loft Conversion Cost?
Prices vary significantly by region and provider. For more information about typical general contractor pricing, see our General Contractor invoice auditing page, or browse all cost guides.
Frequently Asked Questions
Many loft conversions fall under permitted development (no planning needed). Dormers to the front, mansard conversions, and conservation areas typically require planning permission.
Velux conversions take 4-6 weeks. Dormers take 6-8 weeks. Complex conversions (mansard, hip-to-gable) take 8-12 weeks.
A well-designed loft conversion can add 15-20% to your home value. In expensive areas, this can mean a significant return on investment.
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