What affects the cost?
The roof form, usable floor area, staircase position, structural steel, dormers and bathrooms have the biggest impact on a loft conversion budget.
- Conversion type
- Roof structure and head height
- New staircase
- Dormer size
- Bathroom or ensuite
- Fire-safety and insulation work
Typical cost breakdown
Regional planning examples
The examples below apply our published modelling factor to the same national benchmark. They are not claimed as observed city-wide average quotes.
Sources used for this guide
Loft Conversion Cost: 2026 UK Price Guide & Breakdown
Published / checked: August 2026
Used for: Loft conversion type benchmarks
Construction output price indices
Published / checked: 13 August 2026
Used for: Construction price trend and update checks
Frequently asked questions
Which loft conversion is usually cheapest?
A simple rooflight conversion is normally less expensive than dormer, hip-to-gable or mansard work because it changes less of the roof structure.
Related costs
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