Bedroom extensions across Gwynedd
Thinking about a bedroom extension for your Gwynedd 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 priceFrom £24,000 inc VAT
- PlanningUsually a planning application
- Towns covered4
- Site visitFree, no obligation

Towns in Gwynedd
What should I budget for a bedroom extension in Gwynedd?
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 Gwynedd: £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 |
Want a range for your exact size? The guide-price tool takes about a minute.
Who a bedroom extension suits
- Homeowners who want an en-suite master bedroom
- Growing families
- Multi-generational households
New bedrooms on an upper floor need an escape window or a protected route to the outside under the building regulations. We design the window sizes and stair route to meet that from the outset.
Planning and approvals in Gwynedd
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.
In a conservation area, national park, National Landscape or World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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).
Local to Gwynedd
Towns we cover in Gwynedd include Bangor, Gwynedd, Caernarfon, Holyhead, Llangefni. 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.
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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
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.
Common questions in Gwynedd
How long does a bedroom extension take to build in Gwynedd?
On site, typically 14 to 22 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Do I need building regulations approval in Gwynedd?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Who do I contract with for a bedroom extension in Gwynedd?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Will a new bedroom need planning permission?
Upstairs additions usually do. Ground-floor rooms may fall within permitted development, depending on size and position.
Does an en-suite need a window?
No, but it needs mechanical extraction that meets the building regulations. We design the duct route at the drawing stage.
Book a free site visit in Gwynedd
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.