Side return extensions in Gwynedd
Gwynedd homeowners can use us for the whole side return extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide priceFrom £16,500 inc VAT
- PlanningCan be permitted development; party wall notice usual
- Towns covered4
- Site visitFree, no obligation

Towns in Gwynedd
Side return extension prices in Gwynedd
Labour and material costs vary across the UK, so for Gwynedd we use our Wales factor (×0.93). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Gwynedd: £1,950 to £3,530 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £16,500 – £20,000 | £17,500 – £22,500 | £22,000 – £28,500 |
| 2 m × 5.5 m 11 m² | £21,000 – £26,000 | £24,500 – £31,000 | £30,500 – £39,000 |
| 2.2 m × 7 m 15 m² | £29,000 – £35,000 | £33,000 – £42,000 | £41,500 – £53,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Covering 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.
Planning and approvals in Gwynedd
In Wales a single-storey side return can fall within permitted development if it stays within the 4 m height limit and the width rules for side extensions. Conservation areas and listed buildings need consent, and the Party Wall Act applies to work on or near a shared wall.
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).
Is a side return extension right for your house?
- Narrow galley kitchens
- Homes where the garden is too small to lose much depth
- Victorian and Edwardian terraces with a rear outrigger
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
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Common questions in Gwynedd
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 side return 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 my neighbours in Gwynedd be involved?
If a planning application is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Will the kitchen be darker?
Not if the roof is designed well. A glazed roof or a line of rooflights along the boundary usually makes the room brighter than before.
How much does a side return extension cost?
Our guide range is about £1,950 to £3,530 per m² including VAT, so a typical 2 m × 5.5 m infill lands around £24,500 to £31,000 at standard spec in Gwynedd, more in London.
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.