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 Cardiff?
In Cardiff, a rooflight loft conversion typically costs £27,500–£41,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Prices across Wales are typically 8% below the UK average for this kind of work, which is reflected in the range for Cardiff. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rooflight conversion | £27,500–£41,500 |
| Higher specification | £41,500–£52,000 |
The main things that change the cost:
- Floor and roof strengthening
- Fire safety upgrades
- Bathroom or not
- Number of roof windows
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 Cardiff?
The approval route for Cardiff is set by planning law in Wales. In Wales roof windows that sit close to the roof slope are generally permitted development outside protected areas.
The Party Wall etc. Act 1996 applies in Wales, so notices must be served before work on a shared wall, on the boundary, or excavation close to a neighbour’s foundations.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
From survey to sign-off, the job normally involves:
- Floor joists and any steel beams
- Drawings and structural calculations
- Insulation between and under rafters
- Head-height survey
- Electrics, heating and plastering
- Staircase and fire-safe escape route
How long does it take?
Build time is typically 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 Cardiff
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
Our Cardiff coverage includes postcode districts CF10, CF11, CF14 and CF15, and we also work in nearby places such as Penarth, Caerphilly and Barry.
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
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 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 Cardiff
How much does a rooflight loft conversion cost in Cardiff?
In Cardiff, a rooflight loft conversion typically costs £27,500–£41,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
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.
Who approves a rooflight loft conversion in Cardiff?
Planning matters in Cardiff go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Do I need planning permission for a rooflight loft conversion in Cardiff?
In Wales roof windows that sit close to the roof slope are generally permitted development outside protected areas.
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.