Extensions over a garage in Caernarfon: design, approvals and build
From the first sketch to final sign-off, we plan and build over-garage extensions in Caernarfon and the surrounding Gwynedd area.
- Guide price in CaernarfonFrom £22,000 inc VAT
- PlanningAn application to the council is needed
- Build time12–18 weeks on site
- Postcode districtsLL55
Working in Caernarfon
Across LL55, we can visit, measure and advise. We also work in nearby Bangor, Gwynedd (7 miles), Llangefni (10 miles), Holyhead (19 miles).
Just over the Clwyd border, Llandudno is about 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.
Who an over-garage extension suits
- Homes where the landing can connect to the new room
- Detached and link-detached houses with an attached garage
- Families needing a bedroom without losing garden
How much does an over-garage extension cost in Caernarfon?
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 Caernarfon: £1,670 to £3,160 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £22,000 – £27,500 | £23,000 – £30,500 | £30,000 – £38,000 |
| Over a large single garage 16 m² | £26,500 – £33,000 | £31,000 – £40,500 | £40,000 – £51,000 |
| Over a double garage 24 m² | £40,000 – £49,500 | £46,500 – £60,500 | £60,000 – £76,000 |
Try the guide-price tool to see a range for your own size and finish.
Do I need planning permission in Caernarfon?
In Wales a two-storey side extension must be at least 10.5 m from the side boundary to be permitted development, which few houses can meet, so a planning application to the council is the usual route for a room over a garage.
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.
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).
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
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
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Your questions about an over-garage extension in Caernarfon
How long does an over-garage extension take to build in Caernarfon?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 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.
How much does a room over a garage cost?
Our guide range is about £1,670 to £3,160 per m² including VAT. A single-garage room of about 12 m² usually costs £23,000 to £30,500 at standard spec, more if the garage needs rebuilding.
Can I keep using the garage during the build?
Usually not for parking. The garage roof is removed and the space below is used for access and props for part of the 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.