What is a rooflight loft conversion?
A rooflight loft conversion (sometimes called a roof window conversion) keeps the existing roof shape and adds roof windows that sit flush with the slope. The floor is strengthened, a staircase is added and the space is insulated and finished.
It is the least disruptive loft conversion and usually does not need planning permission, but it only works where there is already enough head height under the ridge.
What we handle
- Head-height survey
- Drawings and structural calculations
- Floor joists and any steel beams
- Roof windows installed
- Staircase and fire-safe escape route
- Insulation between and under rafters
- Electrics, heating and plastering
- Building control sign-off
Options to consider
Bedroom or study
Ideal for a bedroom, office or playroom with sloping ceilings.
Eaves storage
Low spaces behind short walls become built-in storage.
Shower room
Possible where there is enough height over the shower.
Conservation-style roof windows
Low-profile windows designed for older roofs.
How much does a rooflight loft conversion cost?
A rooflight loft conversion typically costs £30,000–£45,000 for a typical rooflight conversion across the UK, including VAT at 20% (standard rate). Build time is usually 4 to 6 weeks on site. Design, structural calculations and council fees are extra.
| Region | Guide range (for a typical rooflight conversion) |
|---|---|
| London | £39,000–£58,500 |
| South East | £33,500–£50,500 |
| East of England | £32,000–£47,500 |
| South West | £30,500–£46,000 |
| West Midlands | £29,000–£43,500 |
| East Midlands | £28,500–£43,000 |
| North West | £28,000–£42,500 |
| Yorkshire and the Humber | £28,000–£42,000 |
| North East | £27,000–£40,500 |
| Wales | £27,500–£41,500 |
| Scotland | £29,000–£43,500 |
| Northern Ireland | £26,000–£38,500 |
What changes the price:
- Number of roof windows
- Floor and roof strengthening
- Staircase position
- Bathroom or not
- Fire safety upgrades
- Storage and finishes
Use the guide price tool for a figure based on your measurements, or see all guide prices.
Do I need planning permission?
England
In England roof windows are permitted development if they project no more than 15 centimetres from the roof slope and side-facing windows are obscure-glazed. Listed buildings need consent.
Wales
In Wales roof windows that sit close to the roof slope are generally permitted development outside protected areas.
Scotland
In Scotland rooflights that project no more than 1 metre from the roof are often permitted development, though conservation areas and listed buildings need consent. A building warrant is needed for the conversion itself.
Northern Ireland
In Northern Ireland roof windows that project no more than 15 centimetres from a road-facing roof slope are permitted development outside conservation areas; listed buildings need consent.
Even when planning permission is not needed, building regulations approval (a building warrant in Scotland) usually is. We make the applications and book the inspections.
How long does it take?
Typically 4 to 6 weeks on site. Surveys, design and approvals usually take 6 to 12 weeks beforehand.
How it works
- 01
Free visit
We look at the property, discuss what you want and measure up.
- 02
Design and fixed quote
Drawings, calculations and an itemised price for the agreed specification.
- 03
Approvals
Planning or permitted development, building regulations and neighbour matters.
- 04
Build and sign-off
Built to a written programme, with a completion certificate at the end.
Rooflight loft conversions: questions and answers
Does a rooflight loft conversion need planning permission?
Usually not. In England roof windows are permitted development if they project no more than 15 centimetres from the roof slope, sit no higher than the ridge and any side-facing windows are obscure-glazed. Listed buildings and houses whose rights have been removed need consent. Building regulations approval is always needed.
How much head height do I need?
Around 2.2 metres or more from the top of the ceiling joists to the ridge is a good starting point. Insulation and new floor joists reduce the height.
Is it cheaper than a dormer?
Yes, usually, because the roof shape stays the same. But you gain less full-height floor space.
How long does it take?
Usually 4 to 6 weeks on site.
What about fire safety?
The same escape rules apply as for any loft conversion, so a protected stairway and smoke alarms are typically needed.
Can I have a bathroom?
Yes, where there is enough head height at the shower or bath position.