Flat roof extensions across Antrim
Antrim homeowners can use us for the whole flat roof extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in AntrimFrom £18,000 inc VAT
- PlanningNI permitted development (rear 3–4 m) or planning
- Build time10–16 weeks on site
- Postcode districtsBT41
Included in a typical project
- Lanterns or rooflights with upstands
- Warm-roof design with insulation above the deck
- Falls and outlets designed to drain properly
- Membrane choice: single-ply, EPDM or GRP
Do I need planning permission in Antrim?
In Northern Ireland the Planning (General Permitted Development) Order 2015 lets some single-storey rear extensions go ahead without planning permission, up to 3 m on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Larger, side and two-storey extensions normally need planning permission from the council, and building control approval is separate.
Homes in conservation areas, areas of townscape character and listed buildings have tighter rules, so we always check the property's status and planning history before design starts.
In Northern Ireland building control is run by the councils under the Building Regulations (Northern Ireland). We submit full plans or a building notice and book the inspections through to completion.
Applications are decided by your council, which handles local planning in Northern Ireland.
Local to Antrim
Our survey diary covers Antrim, including BT41. Nearby, we also take on projects in Ballymena (10 miles), Newtownabbey (13 miles), Belfast (14 miles), Lisburn (15 miles).
In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Guide prices for Antrim
Labour and material costs vary across the UK, so for Antrim we use our Northern Ireland factor (×0.86). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Antrim: £1,500 to £2,880 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £18,000 – £21,500 | £21,000 – £27,000 | £26,500 – £35,000 |
| 4 m × 5 m 20 m² | £30,000 – £35,500 | £35,000 – £45,000 | £44,500 – £58,000 |
| 5 m × 6 m 30 m² | £45,000 – £53,000 | £52,500 – £67,500 | £67,000 – £86,500 |
Try the guide-price tool to see a range for your own size and finish.
How the project works
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Your questions about a flat roof extension in Antrim
Do I need building regulations approval in Antrim?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Antrim, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do you cover all of Antrim?
Yes. We cover Antrim and the surrounding parts of County Antrim. Site visits are free and there is no obligation.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,500 to £2,880 per m² including VAT.
Book a free site visit in Antrim
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.