Side extensions for homes in Caernarfon
Our design and build teams take on side extensions in Caernarfon, from the first measured survey through planning and building control to the finished room.
- Guide price in CaernarfonFrom £20,000 inc VAT
- PlanningSingle storey can be permitted development
- Build time10–18 weeks on site
- Postcode districtsLL55
What we take care of
- New openings through the side wall
- Survey, design and street-view drawings
- Foundations near boundaries and any drains
- Planning route checked or application made
- Structure, roof tied into the house
- Windows, doors and finishes to match
Do I need planning permission in Caernarfon?
In Wales a single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house, and it must not come closer to a highway than the existing side wall. Larger side extensions need planning permission.
The planning position for a specific Caernarfon address depends on its history and any designations, which is why we check it at the first visit.
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.
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).
Extensions in and around Caernarfon
Site visits are available across Caernarfon (LL55). Nearby, we also take on projects in Bangor, Gwynedd (7 miles), Llangefni (10 miles), Holyhead (19 miles).
For homes towards Clwyd, Llandudno is around 20 miles away. 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.
Side extension prices 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: £1,630 to £3,160 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £20,000 – £25,000 | £22,500 – £30,000 | £29,000 – £38,000 |
| 3 m × 6 m 18 m² | £29,000 – £35,500 | £34,000 – £44,500 | £43,500 – £57,000 |
| 3 m × 8 m 24 m² | £39,000 – £47,000 | £45,500 – £59,500 | £58,000 – £76,000 |
For a figure based on your own dimensions, use our guide-price tool.
How the project works
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 Caernarfon 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.
Your questions about a side extension in Caernarfon
How long does a side extension take to build in Caernarfon?
On site, typically 10 to 18 weeks once approvals are in place. Before that, allow 6–14 weeks design and approvals.
Do I need building regulations approval in Caernarfon?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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 build over my driveway?
Yes, if the foundations work and you keep any parking the council requires. Drains and services under drives are common, so we check before design.
How much does a side extension cost?
Our guide range is about £1,630 to £3,160 per m² including VAT, depending on specification, so a standard 18 m² single-storey side extension lands around £34,000 to £44,500 in Caernarfon.
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.