Extensions in Caernarfon: design, planning and build
More space without moving: we plan and build extensions across Caernarfon, with one team for the drawings, the council and the build.
- Postcode districtsLL55
- Price regionWales (×0.93)
- Planning rulesWales
- Site visitFree, no obligation
Areas we cover around Caernarfon
We cover Caernarfon and the postcode districts LL55. The same team covers Bangor, Gwynedd (7 miles), Llangefni (10 miles), Holyhead (19 miles), all within easy reach. Llandudno, in Clwyd, is roughly 20 miles from Caernarfon and also on our list.
What works best for Caernarfon houses?
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.
Depending on the plot, single-storey rear extensions and pitched roof extensions are often the strongest options, with side return extensions worth considering where there is room.
Planning and building control in Caernarfon
In Wales a single-storey rear extension can usually project up to 4 m beyond the rear wall without a planning application, if it is no more than 4 m high, keeps eaves to 3 m and overall height to 4 m within 2 m of a boundary, and covers no more than half the land around the original house. Wales has no larger home extension prior approval scheme.
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).
What extensions cost in Caernarfon
We publish guide prices so you can budget before anyone visits. For Caernarfon they are adjusted by ×0.93, the factor we use across Wales.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Orangery extensions | 16 m² | £41,500 – £52,500 |
| Single-storey rear extensions | 20 m² | £38,000 – £48,500 |
| Double-storey extensions | 32 m² | £53,500 – £70,000 |
| Conservatory replacement extensions | 14 m² | £27,500 – £36,000 |
| Wraparound extensions | 25 m² | £53,000 – £67,500 |
Extension types and starting prices
- Kitchen extensions · from £25,000
- Bungalow extensions · from £24,000
- Flat roof extensions · from £19,500
- Planning permission for extensions · from £300
- Conservatory replacement extensions · from £18,500
- Orangery extensions · from £27,500
- Bedroom extensions · from £24,000
- Side extensions · from £20,000
- Side return extensions · from £16,500
- Timber frame extensions · from £19,500
- Single-storey rear extensions · from £19,500
- Extensions over a garage · from £22,000
- Annexe extensions · from £51,000
- Porch extensions · from £3,700
- Building regulations for extensions · from £800
- Utility and boot room extensions · from £13,000
- Wraparound extensions · from £33,000
- Double-storey extensions · from £35,000
- Pitched roof extensions · from £20,500
- Glass box extensions · from £27,500
- Extension plans and drawings · from £1,100
- Home office extensions · from £14,500
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
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
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Caernarfon
How much does an extension cost in Caernarfon?
Using our Wales factor (×0.93), a standard-spec single-storey extension of 20 m² is a guide £38,000 to £48,500 including VAT, and a 32 m² two-storey extension £53,500 to £70,000. Your written price follows the survey.
Do I need planning permission for an extension in Caernarfon?
Not always. It depends on the size, position and your property's history. In Wales many single-storey rear extensions up to 4 m are permitted development.
Do you cover all of Caernarfon?
Yes, including the surrounding parts of Gwynedd. Site visits are free and there is no obligation.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Caernarfon, and the guide-price tool gives a range for your own size and finish in about a minute.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
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.