What does a loft conversion cost in London?
In London: £56,300 to £75,000 for a Dormer version and £30,000 to £40,000 for a Velux (rooflight) at mid-range, including 20% VAT, against £45,000 to £60,000 nationally. Budget starts around £25,500 (Velux (rooflight)), premium runs to £109,400 (Hip to gable). Set your finish level and region below, no email required.
- Dormer: £56,300 to £75,000 mid-range
- Velux (rooflight): £30,000 to £40,000 mid-range
- Hip to gable: £68,800 to £87,500 mid-range
Loft conversion (Dormer), mid-range, London
£56,300 to £75,000
Including 20% VAT. An indication, not a quote: prices vary per trade and property.
Take it further
Prices include 20% VAT. New builds and some energy-saving works can qualify for 0% or reduced VAT; ask your installer.
Got quotes in already? Check if they are fair. Want to know when the money leaves? See the phase-by-phase plan.
Extensions and loft conversions often fall under permitted development. Check before you budget.
What drives the price
- The type: a Velux conversion keeps the roof; a dormer or hip-to-gable rebuilds part of it.
- The stairs: fitting a compliant staircase is often the hardest puzzle of the project.
- Structure: new floor joists and steels are non-negotiable building regulations work.
- A bathroom up top: adds plumbing runs and a share of the boiler's capacity.
- Why no size input? UK guides price lofts per project: the type and the structure drive the bill far more than a metre of floor either way.
- Bats: they are strictly protected, and signs of a roost (droppings, sightings) mean a legally required bat survey before work starts; a few hundred pounds for the survey, and mitigation can run into thousands. Check early, not after the scaffolding is up.
All figures come from the same validated 2026 price data as the calculator above (sources: Checkatrade, MyJobQuote and comparable national 2026 cost guides, checked August 2026; see how we price), so this page and your estimate can never disagree. Outside London? See the national guide, or compare every region in the regional overview. Planning an extension or loft? Check permitted development first.
Frequently asked questions
Which loft conversion type should I price first?
Start with the cheapest that fits your headroom: a Velux conversion if the ridge is high enough, a rear dormer when you need the headroom, hip-to-gable only when the roof shape demands it. The calculator prices all three; a mansard, the fourth type, usually tops even the hip-to-gable range and is not covered here. The planning check tells you which types stay within permitted development.
Do these prices include VAT?
Yes, all ranges include 20% VAT. New builds and some energy-saving works can qualify for 0% or reduced VAT; ask your installer whether your project applies.
Why is London so much more expensive?
Labour is the driver: London trades charge roughly 25% above the national average, and parking, access and waste logistics add friction. Nationally this project runs £45,000 to £60,000; the calculator switches region in one click.
How accurate is this range?
It is a guide range from national 2026 cost guides, adjusted for finish level and region. Real quotes vary per trade, property and specification; treat it as a starting point, budget 10 to 15 percent contingency, and always get at least three itemised quotes.