How much does a loft conversion cost in the UK?
This post may contain affiliate links. At no cost to you, we earn a commission from qualifying purchases.
Costs vary widely depending on the size of your loft, the complexity of the work, and your location. As a rough guide in 2025, most loft conversions in the UK fall between £30,000 and £60,000.
If your loft already has enough headroom, the most affordable option is a roof light (Velux) conversion. This involves adding skylight-style windows, insulation, and flooring without changing the roof shape. Costs typically start around £20,000–£30,000.
For a larger, more complex project such as a mansard conversion, you might be looking at £60,000–£80,000 or more.
Another way to measure is by floor area. Builders often quote around £1,200–£2,000 per square metre for a fully finished loft conversion.
Types of loft conversions and their costs
There’s no one-size-fits-all price, because different styles of loft conversion come with different levels of work.
| Type of conversion | National average cost | London & South East | North of England, Scotland & Wales |
|---|---|---|---|
| Roof light / Velux | £20,000–£30,000 | £25,000–£35,000 | £18,000–£25,000 |
| Dormer | £30,000–£50,000 | £40,000–£55,000 | £28,000–£40,000 |
| Hip-to-gable | £40,000–£65,000 | £50,000–£70,000 | £35,000–£55,000 |
| Mansard | £60,000–£80,000+ | £70,000–£90,000+ | £55,000–£70,000+ |
- Roof light / Velux conversion: The cheapest option. It adds windows but doesn’t change the roof shape. Suitable for lofts with good head height already.
- Dormer conversion: A popular choice. It extends the roof outwards with a dormer box, giving more floor space and headroom.
- Hip-to-gable conversion: Involves changing a sloping end of the roof into a vertical wall, creating extra internal space. Often used in semi-detached houses.
- Mansard conversion: The most expensive, usually requiring major structural work. It creates a flat roof with steep sides, adding maximum usable space.
Additional costs to budget for
The basic build cost is only part of the story. Here are some extras that often catch people out:
| Item | Estimated cost range |
|---|---|
| Planning & building regs | £1,000–£2,000 |
| Structural work (beams, floor) | £2,000–£5,000 |
| Stairs & access | £2,000–£5,000 |
| Bathroom (plumbing & fittings) | £5,000–£10,000 |
| Electrics & lighting | £1,500–£3,000 |
| Insulation & soundproofing | £1,000–£3,000 |
| Finishing touches (flooring, plastering, decorating) | £3,000–£5,000 |
Regional cost differences
Where you live has a big impact on cost.
Labour rates and demand are higher in London and the South East, so expect to pay at the top end of the scale. In the North of England, Scotland, and Wales, costs are usually 15–25% lower.
For example, a dormer conversion that might cost £50,000 in London could come in closer to £35,000–£40,000 in Manchester or Leeds.
How to get an accurate quote
Because so many factors are at play, the only way to know the real cost is to get quotes. A good builder will start with a survey of your roof space to check things like head height, roof structure, and access.
When you compare quotes:
- Check what’s included. Some quotes cover only the shell, while others include finishing.
- Ask about timelines and potential extras.
- Make sure VAT is included so there are no surprises later.
Is a loft conversion worth it?
For many homeowners, yes.
A new bedroom and bathroom in the loft can turn a three-bed into a four-bed with two bathrooms, which is often the difference between staying put or moving.
From a financial point of view, adding a loft conversion can add tens of thousands to the value of your home. From a lifestyle point of view, it can be priceless – whether it’s a quiet home office, a teenager’s hideaway, or a master suite.
However, it’s not always the right move. If your roof space is too small, or if you live in a conservation area with strict planning rules, the costs and hassle might outweigh the benefits.
Final thoughts
A loft conversion is a major project, but one that can transform how you use your home. In 2025, most UK homeowners can expect to spend between £30,000 and £60,000, with costs rising for more complex designs.
The key is to plan carefully, set a realistic budget, and get professional advice early on. Done well, a loft conversion can give you the extra space you need and pay for itself in added value when you sell.
Photo by Curtis Adams
