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 County Londonderry?
In County Londonderry, 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 |
Your quote will depend mainly on:
- Glazing size, specification and lead time
- Cladding material
- Overheating and energy design
- Lighting and finishes
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a glazed extension in County Londonderry?
The approval route for County Londonderry 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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
On a typical glazed extension we handle:
- Building control sign-off
- Energy and overheating calculations where needed
- Large-format sliding doors and fixed glazing
- Cladding or render finish
- Structural design for steel frames and glass supports
- Electrics, heating and finishes
How long does it take?
Allow 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in County Londonderry
Across Northern Ireland, bungalows and chalet bungalows are common, so loft conversions and rear extensions are popular projects.
Towns we cover in County Londonderry include Derry, Coleraine, Limavady and Magherafelt.
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
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about glazed extensions in County Londonderry
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.
How much does a glazed extension cost in County Londonderry?
In County Londonderry, 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.
Can large glass panels be lifted in?
Some need a crane or glass-lifting robot. We plan access during design.
Is VAT charged?
Yes, VAT at the standard 20% rate applies to extensions. Our guide prices include it.
Who approves a glazed extension in County Londonderry?
Planning matters in County Londonderry 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 glazed extension in County Londonderry?
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.