What is a Dormer Loft Conversion?
A dormer is a structural extension that projects vertically from the plane of a sloping roof. It creates additional headroom and floor space in the loft area, making it more comfortable and functional.
Types of Dormer Conversions
- Flat Roof Dormer – Most common, offers the most space.
- Shed Dormer – Sloped roof in the same direction as the main roof.
- Gable Fronted (Doghouse) Dormer – Pitched roof, traditional look.
- Hip Roof Dormer – Slopes on three sides, more complex and expensive.
- L-Shaped Dormer – Ideal for mid-terrace houses; combines two dormers.
Pros
- Increases internal space significantly
- Adds natural light via windows
- Improves property value
- Usually falls under Permitted Development (but check local rules)
Cons
- Aesthetic impact (some find it bulky)
- Flat roofs can require more maintenance>
- Cost varies depending on size and complexity
Estimated Cost (UK 2025)
Basic dormer: £30,000–£50,000
Larger or L-shaped dormers: £45,000–£70,000+
Planning Permission
Often not required if it falls under Permitted Development.
You will need planning permission if:
- It extends beyond the existing roof plane facing a road.
- It exceeds the height of the existing roof.
- You’re in a conservation area.
Building Regulations
Regardless of planning permission, building regs approval is required, covering:
- Structural integrity
- Fire safety
- Insulation
- Staircase access