What a loft conversion costs
How Much Does a Loft Conversion Cost? UK Prices by Type
The price of a loft conversion rises with the structural work its type needs, so a Velux conversion is usually the most affordable and a mansard tends to cost the most. Here are the UK prices by type, per m² and by house, what each job on a 30m² dormer costs, and the hidden costs and contingency to add to the quote.
Loft conversion cost by type and per m²
Checkatrade’s loft conversion cost guide, in a table last updated in March 2026, prices each type of conversion for a 30m² loft, except the bungalow row, which is for 50m². The per m² prices come from the same guide.
| Type | Average | Range | Per m² |
|---|---|---|---|
| Velux (rooflight) | £27,500 | £22,500 to £30,000 | £920 |
| Shell | £30,000 | £22,500 to £37,500 | £1,000 |
| Modular | £45,000 | £30,000 to £60,000 | £1,500 |
| Dormer | £50,000 | £40,000 to £60,000 | £1,670 |
| Hip-to-gable | £60,000 | £50,000 to £70,000 | £2,000 |
| Mansard | £65,000 | £50,000 to £80,000 | £2,170 |
| Bungalow (50m²) | £75,000 | £62,500 to £87,500 |
On the same 30m² loft, the type of conversion you choose moves the average from £27,500 to £65,000 on Checkatrade’s figures. A Velux conversion is usually the most affordable, and a mansard tends to be the most expensive because of the major structural work it involves. Each per m² price is the type’s average divided across the 30m² floor, so a £50,000 dormer works out at £1,670 per m² in Checkatrade’s guide.
Shell and modular conversions
A shell conversion, at around £30,000 on Checkatrade’s figures, covers the main structural work only: the new floor structure, the roof alterations and a dormer if one is required. Plastering, flooring and decoration are done separately, so they need their own prices.
Describing a shell conversion on a quote
Do this
Shell conversion including the new floor structure, roof alterations and a rear dormer, with plastering, flooring and decoration excluded
Not this
Loft conversion to shell stage
A modular conversion costs around £45,000 on Checkatrade’s figures, which give it 2 to 3 weeks. Much of the construction is done in advance, so installation on site can be quicker, with less disruption.
Dormer loft conversion cost breakdown
Checkatrade’s breakdown of a 30m² dormer conversion, last updated in August 2026, splits the £50,000 average across 11 jobs. Two rows leave something out: the scaffolding excludes a temporary roof, and the joinery excludes the staircase, which has its own row.
| Job | Average |
|---|---|
| Project management | £4,000 |
| Scaffolding (excludes temporary roof) | £4,750 |
| Internal preparation | £7,000 |
| Alterations to roof structure | £5,000 |
| Steelwork to support structural changes | £6,000 |
| Roof coverings | £8,250 |
| Electrics and plumbing | £3,250 |
| Joinery (excludes staircase) | £4,500 |
| Staircase | £2,750 |
| Plastering | £2,750 |
| Decoration | £1,750 |
| Total | £50,000 |
A structural engineer usually calculates the steel beams needed to support the new floor and roof, Checkatrade’s cost guide says. Three rows of the breakdown are for the roof itself: the alterations to the roof structure, the steelwork to support the changes and the new roof coverings.
The roof work on a 30m² dormer conversion
| Alterations to the roof structure | £5,000 |
|---|---|
| Steelwork to support the structural changes | £6,000 |
| Roof coverings | £8,250 |
Total £19,250
Part of a 30m² dormer conversion on Checkatrade's figures, from a breakdown that totals £50,000. Checkatrade lists the structural engineer's calculations among the hidden costs.
Loft conversion cost by house type
Checkatrade’s cost guide gives these prices by house type.
| House | Around |
|---|---|
| Terraced house | £50,000 |
| Semi-detached house | £50,000 |
| Detached house | £62,500 |
| Bungalow | £75,000 |
The bungalow price matches the bungalow row in Checkatrade’s type table, which is for a 50m² loft rather than 30m². On a semi-detached house a Velux or dormer conversion is common, and a hip-to-gable conversion is often used to maximise the space, at £60,000 on average for a 30m² loft on Checkatrade’s figures. On a terraced house, a dormer is the most common option.
A well-designed loft conversion can add up to 20% to a property’s value, on Checkatrade’s cost guide.
Hidden costs and contingency
Checkatrade’s cost guide lists architect drawings at £1,000 to £2,000, structural engineer calculations, planning permission fees, party wall agreements and a bat survey at £400 to £750, if one is required, as hidden costs that can add 10 to 15%. Party wall costs depend on the number of surveyors, and one agreed surveyor for you and your neighbour costs £900 to £1,200 for a loft conversion, on Checkatrade’s party wall surveyor cost guide.
Do not budget for the build price alone
Checkatrade says hidden costs can add 10 to 15%, which on a £50,000 dormer conversion is another £5,000 to £7,500 before any contingency.
Checkatrade’s cost guide says many homeowners plan for a contingency of 10 to 15% on top of the quote. The same guide’s saving tips say most builders recommend around 10%.
As a worked example on Checkatrade’s figures, a dormer quoted at £50,000, with architect drawings at £1,000 to £2,000 and a 10% contingency of £5,000, needs a budget of £56,000 to £57,000. The structural engineer’s calculations, planning fees, any party wall costs and a bat survey, where one is required, come on top of that.
Comparing loft conversion quotes in Nottingham
Quotes for the same conversion can differ in what they leave out, so ask every company to show the same items before you compare the totals.
What a loft conversion quote should show
- The type of conversion and the floor area
- Scaffolding, and whether a temporary roof is included
- Steelwork to a structural engineer's calculations
- The staircase, plastering and decoration, or which of them you arrange yourself
- Architect drawings, planning fees and party wall costs, where they apply
- A bat survey, if one is required
- Whether the price includes VAT
Among the Nottingham loft conversion companies compared for dormers and guarantees, Premium Home Conversions in Long Eaton publishes starting prices of £15,000 for a Velux conversion and £30,000 for a dormer. Roof Rooms in Ilkeston gives a 10-year guarantee covering the structural work and all associated works.
Common questions
How much does a loft conversion cost in the UK?
Most loft conversions in the UK cost £27,500 to £75,000 or more, and many homeowners spend around £50,000, on Checkatrade's figures. A Velux conversion is usually the most affordable, and a mansard tends to be the most expensive because of its major structural work.
How much does a dormer loft conversion cost?
A dormer loft conversion costs £50,000 on average for a 30m² loft, with a range of £40,000 to £60,000, on Checkatrade's figures. That is £1,670 per m², and the biggest single job in Checkatrade's breakdown is the roof coverings at £8,250.
How much does a hip-to-gable loft conversion cost?
A hip-to-gable loft conversion costs £60,000 on average for a 30m² loft, with a range of £50,000 to £70,000, on Checkatrade's figures. That is £2,000 per m².
How much does a mansard loft conversion cost?
A mansard loft conversion costs £65,000 on average for a 30m² loft, with a range of £50,000 to £80,000, on Checkatrade's figures. That is £2,170 per m², the highest per m² price Checkatrade gives, because a mansard involves major structural work.
How much does a loft conversion cost per m²?
A loft conversion costs from £920 per m² for a Velux conversion to £2,170 per m² for a mansard, on Checkatrade's figures. In between, a shell conversion costs £1,000 per m², a modular conversion £1,500, a dormer £1,670 and a hip-to-gable £2,000.
How much does a loft conversion cost on a 3 bed semi?
A loft conversion on a semi-detached house costs around £50,000, on Checkatrade's figures. A Velux or dormer conversion is common on a semi, and a hip-to-gable conversion, often used to maximise the space, averages £60,000 on a 30m² loft.
How much contingency should you budget for a loft conversion?
Many homeowners plan a contingency of 10 to 15% on top of the quote, on Checkatrade's cost guide. The same guide's saving tips say most builders recommend around 10%.
Where the figures come from
- Checkatrade, loft conversion cost read 2026-09-17
- Checkatrade, party wall surveyor cost read 2026-09-17
Next
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