Bedroom extensions in Llangefni
From the first sketch to final sign-off, we plan and build bedroom extensions in Llangefni and the surrounding Gwynedd area.
- Guide price in LlangefniFrom £24,000 inc VAT
- PlanningUsually a planning application
- Build time14–22 weeks on site
- Postcode districtsLL77

Covering Llangefni
Postcode districts we cover around Llangefni include LL77. Neighbouring towns we cover include Bangor, Gwynedd (8 miles), Caernarfon (10 miles), Holyhead (11 miles).
For homes towards Clwyd, Llandudno is around 20 miles away. In Wales, terraced houses with rear offshoots are common in the towns, while detached houses and bungalows dominate in rural areas.
What we take care of
- En-suite drainage and ventilation design
- Fire safety: escape windows and smoke alarms to building regulations
- Planning drawings and application
- Structure, roof, insulation and finish
- Heating extended to the new rooms
Do I need planning permission in Llangefni?
In Wales a rear extension of more than one storey can be permitted development only if the ground floor projects no more than 4 m, the upper floor no more than 3 m, it stays at least 10.5 m from the rear boundary and it is not in a conservation area, national park, National Landscape or World Heritage Site. Anything larger needs a planning application to the council.
The planning position for a specific Llangefni address depends on its history and any designations, which is why we check it at the first visit.
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.
Building over or within 3 m of a public sewer needs the water company's consent before the foundations go in.
Applications are decided by the local planning authority (your county or county borough council, or the national park authority).
How much does a bedroom 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: £1,490 to £2,980 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| One bedroom 12 m² | £24,000 – £29,500 | £24,000 – £31,500 | £26,500 – £36,000 |
| Bedroom and en-suite 18 m² | £26,500 – £33,000 | £31,500 – £41,500 | £40,000 – £54,000 |
| Two rooms 30 m² | £44,500 – £54,500 | £53,000 – £68,500 | £66,500 – £89,500 |
Try the guide-price tool to see a range for your own size and finish.
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
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
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions people ask about bedroom extensions
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.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Llangefni, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How long does a bedroom extension take to build in Llangefni?
On site, typically 14 to 22 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Will a new bedroom need planning permission?
Upstairs additions usually do. Ground-floor rooms may fall within permitted development, depending on size and position.
How much does a bedroom extension cost?
Our guide range is about £1,490 to £2,980 per m² including VAT. A bedroom with an en-suite of about 18 m² is typically £31,500 to £41,500 at standard spec, depending on whether it is part of a larger two-storey build.
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.