Loft conversion cost in the UK (2026 guide)
Published guides put a typical UK loft conversion at roughly £30,000 to £85,000 in 2026. The type of conversion matters most. A simple rooflight conversion costs far less than a mansard, and London is dearer than most of the country.
The guides disagree, so use the figures as a benchmark. Get itemised quotes for your own home, because roofs differ.
Loft conversion cost at a glance
| Type | Rough cost per m² | Typical total |
|---|---|---|
| Velux (rooflight) | £1,000 to £1,500 | About £22,500 to £30,000 |
| Dormer | £1,500 to £2,000 | About £40,000 to £60,000 |
| Hip-to-gable | £1,750 to £2,500 | About £50,000 to £70,000 |
| Mansard | £1,750 to £3,000 | About £60,000 to £85,000 or more |
The per-square-metre figures come from MyJobQuote’s national table. The totals are for a standard 30 m² loft in a 2026 summary of UK costs. Checkatrade’s average is around £50,000, with a rooflight conversion averaging about £27,500.
Cost by type
Velux or rooflight conversion
This is the cheapest type, because it keeps the roof shape and adds windows. It suits lofts with enough headroom. It adds less space than a dormer.
Dormer conversion
A dormer adds a box to the roof, which gives more headroom and floor space. It is the most common type, although it costs more than a rooflight. Many dormers need no planning permission in England, but check with your council.
Hip-to-gable conversion
This replaces a sloping side of the roof with a vertical wall. Since it needs a side wall, it suits semi-detached and end-of-terrace homes, and it often combines with a dormer.
Mansard conversion
A mansard changes the whole roof shape and gives the most space. It costs the most, because it almost always needs planning permission.
What a quote should include
A good quote lists structural work, insulation, stairs, windows, electrics, heating and plastering. Ask whether it includes fees, VAT and Building Regulations sign-off. An en-suite bathroom is often priced separately, at about £5,000 to £12,000 in one guide.
What changes the price
- Location. London runs roughly 20% to 25% above many other areas.
- Access. Poor access makes labour dearer.
- Roof condition. Repairs before the conversion add cost.
- Finish. Fitted storage and high-end fittings add up.
- Size. Bigger lofts cost more in total, yet less per square metre.
Rules to check
Many conversions need Building Regulations approval, even though they may need no planning permission. Where the loft shares a wall with a neighbour, the Party Wall Act may apply in England and Wales. In Scotland you may need a building warrant. Ask your builder to confirm what applies, and get it in writing.
How to save
Compare at least three itemised quotes. Choose the simplest type that gives the space you need. Settle your design early, because changes during the job cost more. Our list of questions to ask a builder helps you compare.
Getting quotes
To compare, send us your job and we will pass it to local builders. We do not vet them, so check each one with our guide to finding a tradesman you can trust. You can also read about builders near you.
Where these figures come from
We checked MyJobQuote, Checkatrade (through the Hackney HOA guide), Trade2base, PlanWatch and a 2026 summary of UK loft costs in October 2026. They disagree widely, and many quote per-square-metre rates before VAT and fees. We show overlapping ranges.
Frequently asked questions
How much does a loft conversion cost in 2026?
Guides suggest roughly £30,000 to £85,000, depending on type, size and location, so check your own.
How much is a dormer loft conversion?
About £40,000 to £60,000 for a standard loft in one 2026 summary, and about £1,500 to £2,000 per square metre in MyJobQuote’s national table.
Do I need planning permission for a loft conversion?
Often not for rooflight and many dormer conversions in England, but mansards usually need it. Check with your council before you start.
How long does a loft conversion take?
It depends on the type and the builder. Ask for a written programme and what happens if the job overruns.