Llangefni glass extensions, designed and built
A glass extension in Llangefni starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in LlangefniFrom £27,500 inc VAT
- PlanningWelsh permitted development rules (rear up to 4 m)
- Build time10–16 weeks on site
- Postcode districtsLL77

Local to Llangefni
Across LL77, we can visit, measure and advise. Nearby, we also take on projects in Bangor, Gwynedd (8 miles), Caernarfon (10 miles), Holyhead (11 miles).
Welsh housing ranges from stone terraces in the valleys to render-and-slate houses and modern estates, and the Welsh planning rules differ from England's in several places.
Will the council need to approve it?
In Wales a glazed or orangery-style extension follows the normal single-storey limits (up to 4 m at the rear). Welsh building regulations also limit glazing and heat loss, so glass-heavy designs need calculations.
Homes in conservation areas, national parks, National Landscapes (AONBs) and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building regulations approval is separate from planning. Wales has its own building regulations and approved documents; the council or a registered building control approver checks the plans, inspects the work and issues a completion certificate.
Applications are decided by the local planning authority (your county or county borough council, or the national park authority).
Is a glass extension right for your house?
- Small infill spaces and side returns
- Garden-facing dining rooms
- Period and listed-style houses where a light touch is wanted
Solar gain is the risk. We specify solar-control glass, plan for opening vents or sliding panels, and avoid fully glazed roofs on south-facing extensions unless shading is included.
How much does a glass extension cost in Llangefni?
These guide figures apply our Wales adjustment (×0.93) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Llangefni: £2,790 to £5,390 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2 m × 4 m 8 m² | £27,500 – £33,500 | £27,500 – £35,500 | £31,500 – £43,500 |
| 3 m × 4 m 12 m² | £33,000 – £40,500 | £39,000 – £49,500 | £47,500 – £65,000 |
| 3 m × 6 m 18 m² | £50,000 – £60,500 | £58,500 – £74,000 | £71,500 – £97,500 |
For a figure based on your own dimensions, use our guide-price tool.
Our process, step by step
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
We visit your Llangefni home, measure up, talk through what you want and check the planning position.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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.
Questions people ask about glass extensions
How long does a glass extension take to build in Llangefni?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Will my neighbours in Llangefni be involved?
If a planning application is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Do I need building regulations approval in Llangefni?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Are glass extensions cold in winter?
Modern double or triple glazing with warm-edge spacers and underfloor heating keeps them comfortable. They are not as warm as a solid room, and we explain the trade-off honestly.
How much does a glass extension cost?
Our guide range is about £2,790 to £5,390 per m² including VAT, because structural glass is made to order. A 12 m² standard-spec glass extension is typically £39,000 to £49,500 in Llangefni.
Book a free site visit in Llangefni
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.