What does a loft conversion cost?
As a national mid-range guide: £45,000 to £60,000 for a Dormer version and £22,500 to £30,000 for a Velux (rooflight), including 20% VAT. Budget finishes start around £19,100 (Velux (rooflight)), premium runs to £87,500 (Hip to gable), and London adds a quarter. Set your finish level and region below for an instant estimate, no email required.
- Dormer: £45,000 to £60,000 mid-range
- Velux (rooflight): £22,500 to £30,000 mid-range
- Hip to gable: £55,000 to £70,000 mid-range
What the sources say
Checkatrade, Loft Conversion Cost: £22,500 to £75,000
per type (30 m2): Velux £22,500-30,000, dormer £40,000-60,000, hip-to-gable £50,000-80,000, mansard average £65,000. The guide does not state its VAT treatment. Guide dated 2026-03, opened and checked 2026-08-26.
MyJobQuote, Dormer Loft Conversion Cost: £30,000 to £60,000
average dormer £45,000; medium (20-30 m2) £30,000-45,000, large (30-40 m2+) £45,000-60,000. The guide does not state its VAT treatment. Guide dated 2026-04, opened and checked 2026-08-26.
MyBuilder, House Renovation Cost Guide: £20,000 to £70,000
loft conversion line in the renovation cost table. The guide does not state its VAT treatment. Guide dated undated, opened and checked 2026-08-26.
The national range at the top of this page is chosen inside the spread these guides publish, converted to include 20% VAT where a guide states its prices exclude it. Where guides disagree, both figures stay visible above so you can judge for yourself.
Loft conversion (Dormer), mid-range, Midlands
£45,000 to £60,000
Including 20% VAT. An indication, not a quote: prices vary per trade and property.
Take it further
Nothing here is saved unless you ask. With a free account you can keep this estimate and come back to it later.
Prices include 20% VAT. New builds and some energy-saving works can qualify for 0% or reduced VAT; ask your installer.
On top of whatever you agree with a builder, set aside a contingency of 20% for the unforeseen: structural work on the existing building carries the most unknowns; guidance puts these projects at the top of the contingency range or above. How much contingency you need explains the guidance.
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, built on the sources listed higher up on this page, each opened and checked on 26 August 2026 (see how we price), so this page and your estimate can never disagree. Planning this in London? See the London guide, or compare every region in the regional overview. How to pay for it (remortgage, loan or savings) is its own guide: paying for a renovation. Planning an extension or loft? Check permitted development first. Cannot picture it finished? Upload a photo and see your loft as a finished room, free and without an account.
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.
What should I do first?
Three steps, in this order. First, turn the guide range above into your own number: the calculator on this page adjusts for size, finish level and region in under a minute, free and without email. Second, if the layout matters, bathrooms and kitchens especially, draw the room to scale in the free planner; moving plumbing is usually the biggest hidden cost, and you want to know that before anyone quotes. Third, get at least three itemised quotes and compare them line by line against your range before you commit; the quote check on this site gives you an honest verdict per quote.
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.
How much does the region matter?
A lot: London typically runs 20 to 35 percent above the national average (this site plans with +25%, the quarter mentioned above), and the North of England, Scotland and Northern Ireland sit 10 to 20 percent below. The calculator adjusts for your region automatically, and the regional overview shows every factor.
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.