Costs
How much does a loft conversion cost?
Indicative UK price ranges for a standard specification including VAT, with the factors that push a project up or down.
| Conversion type | Typical cost | Time on site |
|---|---|---|
| Velux / rooflight | £28,000 – £45,000 | 4 – 6 weeks |
| Dormer | £42,000 – £70,000 | 6 – 9 weeks |
| L-shaped dormer | £55,000 – £85,000 | 8 – 11 weeks |
| Hip-to-gable + dormer | £55,000 – £90,000 | 8 – 11 weeks |
| Mansard | £65,000 – £110,000 | 10 – 14 weeks |
| Modular | £50,000 – £85,000 | 5 – 8 weeks |
What drives the price
- Floor area
- Cost scales closely with usable square metres, so head height and roof shape matter as much as footprint.
- Structural work
- Steel beams, new floor joists and roof alterations are a significant share of the budget.
- Bathrooms
- An en-suite typically adds £6,000 to £12,000 once plumbing, tiling and ventilation are allowed for.
- Staircase
- A straightforward run over the existing stairwell is cheapest; borrowing space from a bedroom adds cost.
- Specification
- Glazing, joinery, flooring and built-in storage can move the total by tens of thousands.
- Region
- London and the South East typically run 15–25% above the UK average.
Costs people forget
- Planning or lawful development certificate fees
- Building control and structural calculations
- Party wall surveyor fees where a shared wall is affected
- Relocating water tanks or upgrading the heating system
- Redecoration of the floor below after the staircase is installed
- Flooring, blinds, lighting and furniture
All figures are indicative and are not a contractual offer. An accurate price can only be confirmed after a site survey.
See what your loft conversion may cost
Answer a few simple questions and get an indicative estimate in minutes, plus a copy by email. Free, with no obligation.
Get My Free Estimate