How much does a loft conversion cost in the UK?
A loft conversion costs £22,000 to £75,000 in the UK, typically around £45,000 for the project. Prices reviewed June 2026.
A loft conversion is one of the best-value ways to add a bedroom and often a bathroom without losing garden space. What you pay depends mostly on the roof type you choose.
Price your loft conversion
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Loft conversion cost breakdown
What a loft conversion typically costs, by option:
| Type of conversion | Typical UK cost |
|---|---|
| Rooflight / Velux | £22,000 to £32,000 |
| Dormer (most common) | £40,000 to £58,000 |
| Mansard / hip-to-gable | £55,000 to £75,000 |
| + Add an en-suite bathroom | add £3,500 to £7,000 |
What's included in the price?
A typical loft conversion price includes:
- Structural work, new floor joists and staircase
- Insulation, plastering, electrics and heating
- Windows or dormer construction
- Building control sign-off
What changes the price?
The things that move a loft conversion price most:
Roof type: a rooflight (Velux) conversion is cheapest, a dormer is the common choice, a mansard is the most expensive
Whether you add an en-suite bathroom
Head height and whether the roof needs raising
Finish level and staircase position
Does where you live change the cost?
London and the South East run 15 to 30 percent above the national figures, mainly on labour.
Common questions
Many loft conversions fall under permitted development, but dormers facing a road, mansards, and homes in conservation areas usually need planning permission. Building control sign-off is always required.
A well-built loft conversion that adds a double bedroom and en-suite typically adds more to the property value than it costs, especially in higher-value areas, though that is never guaranteed.
A rooflight or Velux conversion is cheapest because it keeps the existing roof line. A dormer costs more but adds head height and floor space, which is why it is the most common choice.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing.