How Much Does a Loft Conversion Cost? 2026 Prices by Type
A loft conversion costs anywhere from around £20,000 to £90,000 depending on type. Here's what each type involves and where your house is likely to sit.
The price of a loft conversion depends mostly on which type your roof allows. The cheapest keeps the existing roofline and adds rooflights; the dearest rebuilds the roof shape to gain headroom. Published 2026 UK guides put the range at roughly £20,000 to £90,000, with most family homes landing somewhere in the middle.
| Type | What it involves | Typical 2026 range |
|---|---|---|
| Rooflight (Velux) | Keeps the existing roof; adds windows, floor, stairs, insulation | £20,000 – £40,000 |
| Dormer | A box extension out of the roof slope for full-height space | £40,000 – £60,000 |
| Hip-to-gable | Rebuilds a sloping side roof into a vertical gable; common on semis | £50,000 – £70,000 |
| Hip-to-gable + dormer | Both of the above, the usual route to a bedroom and en-suite | £50,000 – £90,000 |
| Mansard | Rebuilds the whole roof slope to near-vertical; the most space, the most work | £65,000+ |
Usually included in the price
- Structure
- Steel beams, new floor joists, roof alterations
- Access
- New staircase, fire-rated doors, escape window
- Finish
- Insulation, plasterboard, skim, electrics, heating extension
- Not usually included
- Bathroom fit-out, decorating, planning and building control fees
Before any of that matters, the roof has to be tall enough. The working test is around 2.2 metres from the top of the ceiling joists to the underside of the ridge. Many Victorian terraces along the coast pass easily; some 1960s and later houses with shallow trussed roofs don't, and those need a more involved (and more expensive) structural solution or a different plan altogether.
Building regulations approval is always needed for a loft conversion, even where planning permission isn't. Fees for drawings, structural calculations and building control typically add £2,000 to £4,000 on top of the figures above.
We survey the loft, the roof structure and where the stair can land before quoting, so the figure you get is for your house, not a national average. See our loft conversions page for what's involved.
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