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 Gwynedd?
In Gwynedd, a rooflight loft conversion typically costs £27,500–£41,500 for a typical rooflight conversion, including VAT at 20% (standard rate). That range is adjusted for Wales, where domestic building work typically costs around 8% below the national average. 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 |
What moves the price most:
- Floor and roof strengthening
- Staircase position
- Number of roof windows
- Fire safety upgrades
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 Gwynedd?
Here is how the rules work for a rooflight loft conversion in Wales. In Wales roof windows that sit close to the roof slope are generally permitted development outside protected areas.
Building regulations in Wales are set by the Welsh Government. Approval comes from the council’s building control service or a registered building control approver, with inspections during the work and a completion certificate at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
What we take care of:
- Staircase and fire-safe escape route
- Insulation between and under rafters
- Floor joists and any steel beams
- Building control sign-off
- Head-height survey
- Drawings and structural calculations
How long does it take?
Build time is typically 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 Gwynedd
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Towns we cover in Gwynedd include Bangor, Llandudno, Holyhead and Caernarfon.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 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
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about rooflight loft conversions in Gwynedd
How much does a rooflight loft conversion cost in Gwynedd?
In Gwynedd, 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.
How long does it take?
Usually 4 to 6 weeks on site.
Can I have a bathroom?
Yes, where there is enough head height at the shower or bath position.
Do I need planning permission for a rooflight loft conversion in Gwynedd?
In Wales roof windows that sit close to the roof slope are generally permitted development outside protected areas.
Is it cheaper than a dormer?
Yes, usually, because the roof shape stays the same. But you gain less full-height floor space.
Do you build rooflight loft conversions in Gwynedd?
Yes. We build rooflight loft conversions across Gwynedd, including postcodes LL21, LL23, LL24, LL25 and LL26. Every project starts with a free home visit.