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 Antrim?
In Antrim, a rooflight loft conversion typically costs £26,000–£38,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Building costs in Northern Ireland run about 14% below the UK average, and the figures for Antrim are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rooflight conversion | £26,000–£38,500 |
| Higher specification | £38,500–£48,000 |
The main things that change the cost:
- Number of roof windows
- Bathroom or not
- Staircase position
- 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 Antrim?
The approval route for Antrim is set by planning law in Northern Ireland. In Northern Ireland roof windows that project no more than 15 centimetres from a road-facing roof slope are permitted development outside conservation areas; listed buildings need consent.
In Northern Ireland building control approval comes from the council, usually through a full plans application or a building notice, with inspections during the work and a completion certificate at the end.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
Handled as part of most rooflight loft conversions:
- Electrics, heating and plastering
- Roof windows installed
- Staircase and fire-safe escape route
- Building control sign-off
- Head-height survey
- Insulation between and under rafters
How long does it take?
Expect 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 Antrim
Northern Ireland has many detached and semi-detached homes on generous plots, which suits single-storey rear extensions and garage conversions.
Our Antrim coverage includes postcode districts BT41, and we also work in nearby places such as Ballymena, Newtownabbey and Belfast.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about rooflight loft conversions in Antrim
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 Antrim?
Yes. We build rooflight loft conversions across Antrim, including postcodes BT41. Every project starts with a free home visit.
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.
How much does a rooflight loft conversion cost in Antrim?
In Antrim, a rooflight loft conversion typically costs £26,000–£38,500 for a typical rooflight conversion, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Do I need planning permission for a rooflight loft conversion in Antrim?
In Northern Ireland roof windows that project no more than 15 centimetres from a road-facing roof slope are permitted development outside conservation areas; listed buildings need consent.
How long does it take?
Usually 4 to 6 weeks on site.