A typical UK loft conversion costs around £50,000 in 2026, but the type sets the price. A roof-light loft costs far less, while a mansard costs far more. This guide gives typical ranges, extra fees and the factors that move a quote.
Loft conversion cost by type
Guide prices vary a lot because each type of loft needs different building work. A roof-light conversion leaves the roof shape alone, while a mansard rebuilds it. Therefore the ranges below climb with the amount of structure involved.
| Type | Typical guide price |
|---|---|
| Roof-light (Velux) | typically £25,000–£40,000 |
| Dormer | typically £45,000–£65,000 |
| Hip-to-gable | typically £55,000–£70,000 |
| Mansard | typically £65,000–£85,000, and more on complex or high-specification jobs |
| Bungalow | typically £45,000–£80,000 depending on the roof and layout |
These ranges come from several 2026 cost guides, rounded to the nearest £5,000. They are guide prices, not quotes from any firm. Cost guides also differ on whether VAT is included, so ask every contractor to state it clearly.
You can read more about each style in our comparison of loft conversion types. If you are still choosing, our overview of loft conversions explains how we arrange them.
Why the type changes the price
A roof-light conversion is the cheapest because the roof stays in place. The work is mainly a new floor, stairs, insulation and windows set into the slope. Because there is less structure to build, the job also moves faster.
A dormer loft conversion adds a box to the roof, which creates floor area and head height. The extra structure costs more, yet you gain the most usable space for the money. Large or L-shaped dormers cost more again.
A mansard loft conversion is usually the dearest type. The whole roof slope is rebuilt to a steep angle, and the job usually needs planning permission. In return, the result is a full extra storey.
Cost per square metre
Guides also quote a rule of thumb of roughly £1,250–£2,500 per m². This helps you sense-check a quote against the floor area you gain. However, it hides big differences, because stairs and a bathroom cost the same whether the room is small or large.
For example, a small room with an en-suite can cost more per m² than a larger bedroom without one. Adding an en-suite typically adds £5,000–£10,000, and more if a new soil stack is needed. The biggest variable is how the waste pipe leaves the house.
Fees on top of the build
Professional fees sit alongside the building contract. One 2026 guide gives these typical ranges.
- Architectural drawings: £1,500–£4,000
- Structural engineer: £750–£2,500
- Building Regulations: £600–£1,500
- Party wall surveyor: £1,000–£2,500+
This is a single-source guide, so treat the numbers as a prompt for questions rather than a budget. Our guide to party wall agreements for loft conversions explains when the surveyor fee applies. It only matters if you share a wall with a neighbour.
What pushes a quote up
Several factors change the final number, and most of them are visible before work starts.
- Roof structure. Old cut roofs with purlins and braced timbers need more steelwork than modern trusses.
- Stairs. Losing space on the floor below to fit a stair can force other layout changes.
- Head height. A low ridge may need the roof raised, which adds cost.
- Access. Tight streets and no parking slow deliveries and raise labour costs.
- Specification. Bespoke windows, built-in storage and underfloor heating all add up.
London and the South East are dearer. Guides put the premium at typically 15–25% more than elsewhere in the UK. Our pages on loft conversions in London and loft conversions in Manchester cover the local picture, and the same applies to loft conversions in Birmingham and loft conversions in Bristol.
Planning, regulations and timing
Cost is only part of the picture, since time on site also affects what you pay. Our guide to how long a loft conversion takes breaks down each stage. Meanwhile, a longer build can mean more scaffold hire and more time living with the disruption.
Most budgets also forget the value side of the sum. Our article on whether a loft conversion adds value looks at what the finished room may be worth. That helps you decide how much to spend.
Ways to keep the cost sensible
You can control some of the price without cutting corners on structure. Choose the simplest conversion your roof allows, because every extra change to the roof shape adds steel, labour and scaffold time. Similarly, stack the new bathroom above an existing one so the waste pipe stays short.
Decide on the layout before the build begins. Changing a door, a window or a stair position after the structure is in costs far more than choosing it on paper. As a result, a clear brief and early drawings are often the cheapest decisions you make.
Finally, keep the finishes in proportion to the rest of the house. A loft that is fitted out far above the standard of the floors below rarely earns its extra cost back. Meanwhile, spend where it counts, on insulation, sound insulation and a well-built stair.
What to ask before you sign
Ask every contractor the same questions so the answers line up. Does the price include VAT? Who pays for the structural engineer, the drawings and the Building Regulations fees? What happens if hidden defects appear once the roof is opened up?
Ask also for a programme in weeks, a payment schedule tied to stages, and a list of exclusions. Clear answers up front protect both sides. Vague answers are a warning sign, because they leave room for extra charges later.
Paying for the work
Many owners fund a loft from savings, a remortgage or a further advance. Each route has a different cost over time. We cover the options in our guide to how to pay for a loft conversion.
Keep a contingency for surprises such as hidden timber defects or old wiring. Setting aside a sensible margin up front is cheaper than stopping mid-build to find money.
Getting a reliable price
A good quote lists the structure, stairs, windows, insulation, electrics, plastering and finishing separately. Therefore you can compare two quotes line by line instead of by total. If one price looks far lower, check what has been left out.
Tell us about your roof, your house type and the room you want, and we will arrange a price for your own loft. Send your details through our contact form to start.
