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 Gwynedd?
In Gwynedd, a glazed extension typically costs £2,600–£3,850 per m² of floor area, including VAT at 20% (standard rate). For a typical 18 m² project that is roughly £47,000–£69,500. Building costs in Wales run about 8% below the UK average, and the figures for Gwynedd are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (13 m²) | £34,000–£50,000 |
| Typical project (18 m²) | £47,000–£69,500 |
| Larger project (25 m²) | £65,000–£96,000 |
| Rate per m² | £2,600–£3,850 |
The main things that change the cost:
- Glazing size, specification and lead time
- Lighting and finishes
- Steel framing
- Cladding material
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a glazed extension in Gwynedd?
Before anything is built in Gwynedd, we confirm which approvals apply in Wales. In Wales a single-storey rear extension is often permitted development: up to 4 metres beyond the rear wall and up to 4 metres high, with eaves no higher than 3 metres within 2 metres of a boundary and no more than half the land around the original house covered. Wales has no larger home extension prior approval route, so deeper extensions need a planning application, as do extensions to flats, listed buildings and houses whose rights have been removed.
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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
What we take care of:
- Building control sign-off
- Contemporary design and planning drawings
- Cladding or render finish
- Large-format sliding doors and fixed glazing
- Energy and overheating calculations where needed
- Foundations, walls and insulated roof
How long does it take?
Allow 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in Gwynedd
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
Towns we cover in Gwynedd include Bangor, Llandudno, Holyhead and Caernarfon.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about glazed extensions in Gwynedd
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.
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.
How much does a glazed extension cost in Gwynedd?
In Gwynedd, a glazed extension typically costs £2,600–£3,850 per m² of floor area, including VAT at 20% (standard rate). A typical 18 m² project comes to roughly £47,000–£69,500. Your fixed price depends on the survey and drawings.
Do you build glazed extensions in Gwynedd?
Yes. We build glazed extensions across Gwynedd, including postcodes LL21, LL23, LL24, LL25 and LL26. Every project starts with a free home visit.
Do I need planning permission for a glazed extension in Gwynedd?
In Wales a single-storey rear extension is often permitted development: up to 4 metres beyond the rear wall and up to 4 metres high, with eaves no higher than 3 metres within 2 metres of a boundary and no more than half the land around the original house covered. Wales has no larger home extension prior approval route, so deeper extensions need a planning application, as do extensions to flats, listed buildings and houses whose rights have been removed.
Is triple glazing necessary?
Not always. High-performance double glazing can meet the standards; triple glazing helps in exposed locations.