How much does a loft conversion cost? How long will it take?
Loft conversion costs depend on the type and the house: room (Velux) conversions start from around £20,000 (6-8 weeks), dormers from around £25,000 (12-14 weeks), and mansards from around £50,000.
The pricing of a loft conversion depends on multiple variables including the conversion type, your house structure, construction quality, features, skylights, bathrooms, glazing, dimensions, area, and roof type (traditional cut or truss).
There are also additional costs you should budget for separately:
- Drawings and structural calculations for planning and building regulations (£900-£3,000)
- Party wall agreement (around £1,000 if an agreed surveyor is used)
- Insurance
- Bat survey (around £400)
- New boiler and water tank removal, asbestos removal
- Roof repair, render/cladding (with scaffolding)
Adding a loft room / Velux loft conversion
This type requires a minimum of 2.2m headroom. The work includes floor reinforcement, skylights, insulation, the staircase, electrics, lighting, heating and fire safety measures.
Costs start from around £20,000. This typically takes 6 to 8 weeks.
Dormer loft conversion
This type needs a minimum of 2.2m headroom, or £6,000+ for a ceiling drop. Costs vary by size and complexity, and it typically takes 12 to 14 weeks. Indicative starting costs:
- General starting cost: around £25,000
- Mid-terrace: around £35,000
- Semi-detached: around £45,000
- Detached: around £55,000
Mansard loft conversion
This is the most expensive option as it replaces the entire roof. Costs start from around £50,000.
These figures are general market guidance from 2020 and should be treated as a starting point; get multiple quotes before you commit.