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 Chiswick?
In Chiswick, 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 Chiswick 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 main things that change the cost:
- Fire safety upgrades
- Storage and finishes
- Floor and roof strengthening
- Number of roof windows
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a rooflight loft conversion in Chiswick?
Approvals for a rooflight loft conversion in Chiswick follow the rules for 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.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
The work we manage on a rooflight loft conversion:
- Building control sign-off
- Insulation between and under rafters
- Electrics, heating and plastering
- Head-height survey
- Drawings and structural calculations
- Floor joists and any steel beams
How long does it take?
The build itself usually takes 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 Chiswick
Many London boroughs have conservation areas and detailed design guides, so early design advice saves time at the planning stage.
From W4 outwards, we take on projects throughout Chiswick and the surrounding parts of Greater London.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 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 Chiswick
Who approves a rooflight loft conversion in Chiswick?
Planning matters in Chiswick go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.
What about fire safety?
The same escape rules apply as for any loft conversion, so a protected stairway and smoke alarms are typically needed.
How long does it take?
Usually 4 to 6 weeks on site.
How much does a rooflight loft conversion cost in Chiswick?
In Chiswick, 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.