Loft conversion costs in London in 2026
A loft conversion in London will typically cost between £60,000 and £130,000 in 2026, depending on the type of conversion, size of the loft, specification level, and your location within Greater London.
The London premium over equivalent work elsewhere in the UK is typically 20–40%, driven by higher trade labour rates, ULEZ and Congestion Charge logistics costs, and longer lead times for specialist subcontractors.
Cost by conversion type (London, 2026)
| Conversion type | Typical London cost |
|---|---|
| Rooflight conversion | £25,000–£45,000 |
| Dormer (rear) | £55,000–£90,000 |
| Dormer (rear) with en-suite | £65,000–£105,000 |
| Hip-to-gable conversion | £60,000–£95,000 |
| Hip-to-gable with rear dormer | £75,000–£120,000 |
| Mansard conversion | £85,000–£130,000+ |
All figures include structural floor, staircase, insulation, windows, basic finishes, and Building Regulations compliance. En-suite bathroom costs are included where stated. Second-fix materials vary.
What drives the cost up in London
Labour rates
London carpenters, electricians, plumbers, and plasterers earn 20–40% more than equivalent trades in the Midlands or North. A specialist loft conversion carpenter in South East London may charge £300–£450 per day.
Structural complexity
Most London lofts are Victorian or Edwardian terraced houses with traditional cut-roof structures. Converting these properly requires careful removal of purlins and ceiling joists, insertion of steel beams, and often temporary propping. On a party wall structure, this adds cost and Party Wall Agreement requirements.
The staircase
A new staircase is one of the highest cost items. A straight flight in a simple position costs £2,500–£4,500 installed. An alternating tread staircase (for tight spaces) costs £4,000–£6,500. A bespoke helical or open-tread design can reach £15,000–£25,000.
Planning and heritage
London has a higher concentration of Conservation Areas, Article 4 Directions, and listed buildings than most UK cities. In Conservation Areas, front-facing dormers typically require planning permission. Mansard conversions in Article 4 areas always need consent.
London borough cost comparison
- Inner London (Westminster, Kensington & Chelsea, Islington): Add 20–30% to mid-range figures
- East London (Hackney, Tower Hamlets, Newham): Within 10% of mid-range figures
- South London (Lambeth, Lewisham, Southwark): Within 5–12% of mid-range
- West London (Ealing, Hammersmith, Richmond): Mid-range; Richmond adds heritage premium
- North London (Barnet, Enfield, Haringey): Generally mid-range for terraced work
What is included (and what is not)
Typically included: structural works (new floor, steels, propping), roof alterations (dormer construction or rooflight openings), Velux or equivalent roof windows, staircase supply and fit, insulation to current Part L standards, plasterboard and skim, electrics (lighting, sockets, fuse spur), heating (extension of existing system), basic decoration.
Not typically included: en-suite unless specified, joinery and fitted storage, flooring, high-specification bathroom, structural engineer fees (£1,500–£4,000), architect or designer fees if used, Building Control fees (£2,000–£4,000), Party Wall Surveyor fees (£1,200–£2,500 per adjoining neighbour).
Getting an accurate quote
Any quote generated without a site visit and survey of the existing loft is indicative only. A properly prepared quote requires the contractor or their representative to: measure the loft, assess the existing roof structure, check head height at different points, identify the best staircase position, and assess the feasibility of the en-suite plumbing route.
Get at least 3 written quotes on the same specification. Check each contractor Builder Score on Dwellinger before inviting them to site.