How Much Does a Loft Conversion Cost in 2026?
A loft conversion is one of the best-value ways to add a bedroom and increase your home’s value. Cost depends on the conversion type, size and finish.
Cost breakdown
| Rooflight / Velux conversion | £20,000–£35,000 |
| Dormer conversion | £35,000–£55,000 |
| Hip-to-gable conversion | £40,000–£60,000 |
| Mansard conversion | £50,000–£75,000 |
| En-suite addition | £3,000–£6,000 |
What affects the price
- •Conversion type and roof structure
- •Staircase position and building regs
- •Insulation, windows and finish
- •Plumbing for an en-suite
- •Planning permission if required
FAQs
Does a loft conversion add value?
A well-built loft conversion typically adds 15–20% to a property’s value, often more than it costs to build.
Do I need planning permission for a loft conversion?
Many fall under permitted development, but dormers and larger conversions may need planning permission. Building regulations always apply.
How long does a loft conversion take?
Most take 6–10 weeks depending on type and complexity.
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