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 Colwyn Bay?
In Colwyn Bay, 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. The guide for Colwyn Bay reflects typical costs in Wales, roughly 8% below the UK-wide figure. 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 biggest cost drivers are:
- Cladding material
- Access for large glass panels
- Glazing size, specification and lead time
- Lighting and finishes
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 Colwyn Bay?
The approval route for Colwyn Bay is set by planning law 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
On a typical glazed extension we handle:
- Structural design for steel frames and glass supports
- Building control sign-off
- Foundations, walls and insulated roof
- Contemporary design and planning drawings
- Electrics, heating and finishes
- Energy and overheating calculations where needed
How long does it take?
The build itself usually takes 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 Colwyn Bay
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
If your home is in Colwyn Bay or close by in Llandudno, Rhyl and Prestatyn, a free home visit is the first step.
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 pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about glazed extensions in Colwyn Bay
How long does a glazed extension take in Colwyn Bay?
Typically 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Design and approvals beforehand usually take 3 to 4 months.
Is triple glazing necessary?
Not always. High-performance double glazing can meet the standards; triple glazing helps in exposed locations.
How much does a glazed extension cost in Colwyn Bay?
In Colwyn Bay, 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.
Is VAT charged?
Yes, VAT at the standard 20% rate applies to extensions. Our guide prices include it.
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 Colwyn Bay?
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.
