Caernarfon bedroom extensions, designed and built
Thinking about a bedroom extension for your Caernarfon home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.
- Guide price in CaernarfonFrom £24,000 inc VAT
- PlanningUsually a planning application
- Build time14–22 weeks on site
- Postcode districtsLL55
What should I budget for a bedroom extension in Caernarfon?
Prices below are for Caernarfon, using the Wales factor of ×0.93. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Caernarfon: £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 |
For a figure based on your own dimensions, use our guide-price tool.
Working in Caernarfon
Across LL55, we can visit, measure and advise. Neighbouring towns we cover include Bangor, Gwynedd (7 miles), Llangefni (10 miles), Holyhead (19 miles).
Llandudno, in Clwyd, is roughly 20 miles from Caernarfon and also on our list. 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.
Planning rules that apply in Caernarfon
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.
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.
The Party Wall etc. Act 1996 applies in Wales as in England: notice must be served before work to a shared wall, building on the boundary, or excavating close to a neighbour's foundations.
Applications are decided by the local planning authority (your county or county borough council, or the national park authority).
What is included
- Fire safety: escape windows and smoke alarms to building regulations
- Structure, roof, insulation and finish
- Heating extended to the new rooms
- Layout options: two-storey, over-garage or ground floor
- En-suite drainage and ventilation design
- Planning drawings and application
What happens next
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
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 bedroom extensions
Do you cover all of Caernarfon?
Yes. We cover Caernarfon and the surrounding parts of Gwynedd. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Caernarfon, 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 Caernarfon?
On site, typically 14 to 22 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Can I add a ground-floor bedroom for a relative?
Yes. A ground-floor bedroom with an accessible shower room is a common request. If it will be lived in as a self-contained home, planning treats it differently, so tell us how it will be used.
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 Caernarfon
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.