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 Kensington?
In Kensington, a rooflight loft conversion typically costs £39,000–£58,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Building costs in London run about 30% above the UK average, and the figures for Kensington are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rooflight conversion | £39,000–£58,500 |
| Higher specification | £58,500–£73,000 |
The biggest cost drivers are:
- Floor and roof strengthening
- Fire safety upgrades
- Number of roof windows
- Staircase position
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a rooflight loft conversion in Kensington?
Before anything is built in Kensington, we confirm which approvals apply 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.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
We check this for your address before design work starts, so there are no surprises later.
What we handle
From survey to sign-off, the job normally involves:
- Roof windows installed
- Head-height survey
- Staircase and fire-safe escape route
- Drawings and structural calculations
- Floor joists and any steel beams
- Building control sign-off
How long does it take?
Expect 4 to 6 weeks on site. Before that, surveys, drawings and approvals usually take 6 to 12 weeks, longer if the council asks for changes.
Building in Kensington
Victorian and Edwardian terraces dominate many London streets, which is why side return, wraparound and mansard projects are so common here.
If your home is in Kensington or close by in Chelsea, Fulham and Hammersmith, a free home visit is the first step.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about rooflight loft conversions in Kensington
Can I have a bathroom?
Yes, where there is enough head height at the shower or bath position.
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 a rooflight loft conversion take in Kensington?
Typically 4 to 6 weeks on site. Design and approvals beforehand usually take 6 to 12 weeks.
How much does a rooflight loft conversion cost in Kensington?
In Kensington, a rooflight loft conversion typically costs £39,000–£58,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
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.