Loft Conversion Cost Summary
Most loft conversions in the UK cost between £40,000 and £60,000. A real dormer conversion we completed came to £55,000, including a bathroom and a good standard of finish. As a rough guide, loft conversion cost per m2 runs from £1,250 to £2,000.
The exact figure depends on the type of conversion, the structural work involved, whether you add a bathroom, and the level of finish. In other words, the loft above your head is a bit of a mystery box until someone measures it. The rest of this guide opens that box and breaks the £55,000 down line by line, with real numbers from a job we actually delivered, not a number we plucked from the rafters.
Loft Conversion Cost Per m2 and Pricing Basis
A loft conversion is priced as a whole project, not by the hour. The two figures most useful for planning are the total and the cost per square metre.
- Total project cost (this example): £55,000
- Typical UK range: £40,000 to £60,000
- Loft conversion cost per m2: £1,250 to £2,000
- Pre construction share of budget: around nine percent
The per m2 figure rises with the standard of finish and falls for simpler roof light conversions. We use it as a planning guide, not a fixed quote.
Pre Construction Costs
Before any building starts, your project needs drawings, structural calculations, and building control sign off. This stage is not optional and is easy to forget when budgeting.
- Architectural drawings: set out the new layout
- Structural engineer calculations: prove the design is safe
- Building control fees: formally approve the work
On this job these came to £5,000 combined, around nine percent of the total. It is the least exciting £5,000 you will ever spend, no one frames a structural calculation, but skip it and the build does not legally happen. Leaving it out of a quote also makes a price look lower than it really is, so we always itemise it for our loft conversion clients.
Loft Conversion Cost Breakdown by Item
The table below shows the full £55,000 broken down by item. These figures include labour and materials for each stage of the build we completed.
| Item | Cost |
|---|---|
| Drawings, calculations and building control fees | £5,000 |
| Structural works | £9,000 |
| Dormer construction | £15,000 |
| Windows and roof lights | £3,000 |
| Staircase installation | £2,000 |
| Plumbing and electrics | £7,000 |
| Insulation and fire upgrades | £6,000 |
| Internal finishing | £8,000 |
| Total | £55,000 |
The dormer construction is the single largest cost at £15,000, which is typical. It is the work that creates full height headroom and turns a cramped loft into a proper room, the difference between a space you stand up in and one you apologise to guests about. We cover this in more detail on our dormer loft conversion page.
Loft Conversion Cost by Type
The conversion type is the biggest single factor in your total. The table below shows typical UK ranges for each, based on the work we quote across South Yorkshire, Leeds, and Manchester.
| Conversion type | Typical cost range | Best for |
|---|---|---|
| Roof light (Velux) | £25,000 to £40,000 | Lofts with enough existing headroom |
| Dormer | £45,000 to £60,000 | Adding headroom and floor space |
| Hip to gable | £50,000 to £70,000 | Semi detached and end terrace homes |
| Mansard | £55,000 to £80,000 | Maximum space, often in conservation areas |
Our £55,000 example was a dormer with a bathroom, which sits in the middle of this range.
Loft Conversion Cost by Property Type
The shape and age of your home also moves the price. This table shows how property type tends to affect a dormer conversion budget.
| Property type | Typical dormer cost | Note |
|---|---|---|
| Terraced | £40,000 to £55,000 | Access can add to labour time |
| Semi detached | £45,000 to £60,000 | Often suits a hip to gable upgrade |
| Detached | £50,000 to £65,000 | More roof space, more options |
| Bungalow | £45,000 to £62,000 | Whole new floor, more structural work |
What Affects the Price
Several factors move the final cost up or down.
- Type of conversion: roof light costs least, dormer sits in the middle, hip to gable and mansard cost more.
- Adding a bathroom: pushes up plumbing, electrics, and finishing costs.
- Level of finish: premium flooring and fittings raise the internal finishing total.
- Structural work needed: more steel and reinforcement means higher cost.
- Property type: terraced, semi detached, and detached homes each present different challenges.
How to Avoid Overpaying
A little preparation keeps your budget predictable, and your future self grateful.
- Get an itemised quote so you can see each cost, like the breakdown above.
- Check that drawings, calculations, and building control are included.
- Confirm whether materials are part of the quoted price.
- Decide on your level of finish early, since it moves the budget most.
- Use a registered, insured builder so you are not paying twice to fix poor work. The cheapest quote and the most expensive lesson are often the same one.
Frequently Asked Questions
How much does a loft conversion cost in the UK?
A dormer loft conversion with a bathroom and a good standard of finish cost £55,000 on a recent project we completed. Most UK loft conversions fall between £40,000 and £60,000, depending on the type of conversion, whether you add a bathroom, and the level of finish.
What is the most expensive part of a loft conversion?
The dormer construction is usually the single largest cost. On this project it came to £15,000, reflecting the new structure, roofing, and weatherproofing needed to extend out from the existing roof slope.
What is the loft conversion cost per m2?
Loft conversion cost per m2 in the UK generally falls between £1,250 and £2,000, depending on the type of conversion and standard of finish. Higher specification fittings and added bathrooms push the figure toward the upper end.
About the Author
This guide was written by Sophian, co-owner of Designed to Build, drawing on real project figures from loft conversions we have delivered across South Yorkshire, Leeds, and Manchester. Designed to Build holds a 5.0 rating from 24 Google reviews. Read more on our about page or get in touch.
Get an Accurate Loft Conversion Quote
The only way to know your real loft conversion cost is to have your property and plans assessed. At Designed to Build we handle loft conversions across South Yorkshire, Leeds, and Manchester, and we give clear, itemised quotes so you can see exactly what you are paying for.
Get your loft conversion quote from Designed to Build
Cost ranges marked as UK typical (conversion type, property type, per m2, and the £40,000 to £60,000 average) are Designed to Build planning estimates based on jobs we quote in our service area. The £55,000 itemised breakdown is the actual cost of a completed project.