Cost guide
How much does a loft conversion cost?
Published industry ranges by conversion type, so you can budget sensibly before getting a quote.
UK loft conversion costs vary sharply by type: a rooflight (Velux) conversion typically runs £22,500–£30,000, a dormer £40,000–£60,000, a hip-to-gable £50,000–£70,000 and a mansard £50,000–£80,000, according to Checkatrade and HomeOwners Alliance industry cost guides. These are general UK ranges for a typical loft, not a quote for your property.
Last updated 17 August 2026
| Range | ||
|---|---|---|
| Rooflight (Velux) conversion — typical 30m² loft | £22,500–£30,000 | Total project |
| Dormer conversion — typical 30m² loft | £40,000–£60,000 | Total project |
| Hip-to-gable conversion — typical 30m² loft | £50,000–£70,000 | Total project |
| Mansard conversion — typical 30m² loft | £50,000–£80,000 | Total project |
| Per m² rate (all types, general) | £1,250–£2,500 | Per m² |
Sources: Checkatrade (updated March 2026, figures verified by CIOB & RICS member estimators per Checkatrade), HomeOwners Alliance (2026 guide)
Key points
- The type of conversion your roof structure allows — a hip-to-gable or mansard involves more structural work than a rooflight conversion, and generally costs more as a result.
- Head height and whether the existing roof structure needs raising or restructuring to meet building regulations.
- Whether you're adding an en-suite bathroom, which brings in new plumbing runs.
- Roof window and dormer window specification.
- Structural work to strengthen the floor to take habitable-room loading.
These are general published ranges, not a quote. Get an estimate based on your own project.
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