What is a glazed extension?
A glazed or contemporary extension uses large panes of glass, slim aluminium frames and modern cladding to create a bright room that contrasts with the original house. Frameless corners, structural glass roofs and minimal sliding doors are typical features.
How much does a glazed extension cost in Antrim?
In Antrim, a glazed extension typically costs £2,400–£3,600 per m² of floor area, including VAT at 20% (standard rate). For a typical 18 m² project that is roughly £43,000–£65,000. That range is adjusted for Northern Ireland, where domestic building work typically costs around 14% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (13 m²) | £31,000–£47,000 |
| Typical project (18 m²) | £43,000–£65,000 |
| Larger project (25 m²) | £60,000–£90,000 |
| Rate per m² | £2,400–£3,600 |
The biggest cost drivers are:
- Lighting and finishes
- Cladding material
- Steel framing
- Glazing size, specification and lead time
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a glazed extension in Antrim?
The approval route for Antrim is set by planning law in Northern Ireland. In Northern Ireland the Planning (General Permitted Development) Order (Northern Ireland) 2015 allows single-storey rear extensions of up to 3 metres on attached houses and 4 metres on detached houses, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary. Houses with removed rights need planning permission, listed buildings need consent, and in conservation areas extensions must stay single-storey and must not come forward of the front or side walls.
Northern Ireland has no Party Wall Act. Work on shared walls relies on agreement with the neighbour and common law, so we agree the arrangements in writing before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
On a typical glazed extension we handle:
- Cladding or render finish
- Foundations, walls and insulated roof
- Large-format sliding doors and fixed glazing
- Energy and overheating calculations where needed
- Structural design for steel frames and glass supports
- Contemporary design and planning drawings
How long does it take?
Allow 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Antrim
Northern Ireland has many detached and semi-detached homes on generous plots, which suits single-storey rear extensions and garage conversions.
We work across Antrim and neighbouring areas such as Ballymena, Newtownabbey and Belfast. Postcodes we cover in Antrim include BT41.
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
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about glazed extensions in Antrim
How long do large glass panels take to arrive?
Often 6 to 10 weeks after final measurements, so we order them as soon as the structure is built.
Can large glass panels be lifted in?
Some need a crane or glass-lifting robot. We plan access during design.
Will a glass extension be too hot in summer?
It can be if poorly designed. Solar-control glass, roof overhangs and opening vents reduce overheating, and building regulations may require calculations to show the design works.
Do I need planning permission for a glazed extension in Antrim?
In Northern Ireland the Planning (General Permitted Development) Order (Northern Ireland) 2015 allows single-storey rear extensions of up to 3 metres on attached houses and 4 metres on detached houses, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary. Houses with removed rights need planning permission, listed buildings need consent, and in conservation areas extensions must stay single-storey and must not come forward of the front or side walls.
How much does a glazed extension cost in Antrim?
In Antrim, a glazed extension typically costs £2,400–£3,600 per m² of floor area, including VAT at 20% (standard rate). A typical 18 m² project comes to roughly £43,000–£65,000. Your fixed price depends on the survey and drawings.
Do you build glazed extensions in Antrim?
Yes. We build glazed extensions across Antrim, including postcodes BT41. Every project starts with a free home visit.