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.
How much does a rooflight loft conversion cost in Swanley?
In Swanley, a rooflight loft conversion typically costs £33,500–£50,500 for a typical rooflight conversion, including VAT at 20% (standard rate). That range is adjusted for the South East, where domestic building work typically costs around 12% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rooflight conversion | £33,500–£50,500 |
| Higher specification | £50,500–£63,000 |
What moves the price most:
- Fire safety upgrades
- Staircase position
- Bathroom or not
- Number of roof windows
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a rooflight loft conversion in Swanley?
Whether you need planning permission depends on your house and its location in 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
On a typical rooflight loft conversion we handle:
- Floor joists and any steel beams
- Head-height survey
- Roof windows installed
- Drawings and structural calculations
- Building control sign-off
- Staircase and fire-safe escape route
How long does it take?
Allow 4 to 6 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Swanley
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
If your home is in Swanley or close by in Orpington, Sidcup and Dartford, a free home visit is the first step.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about rooflight loft conversions in Swanley
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.
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.
Is it cheaper than a dormer?
Yes, usually, because the roof shape stays the same. But you gain less full-height floor space.
How much does a rooflight loft conversion cost in Swanley?
In Swanley, a rooflight loft conversion typically costs £33,500–£50,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
How long does a rooflight loft conversion take in Swanley?
Typically 4 to 6 weeks on site. Design and approvals beforehand usually take 6 to 12 weeks.