Side return extensions in Thame: design, approvals and build
A side return extension in Thame starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in ThameFrom £20,000 inc VAT
- PlanningOften permitted development; party wall notice usual
- Build time10–14 weeks on site
- Postcode districtsOX9
Do I need planning permission in Thame?
In England a single-storey side return infill is often permitted development if it stays within the height limits and is no wider than half the width of the original house. Conservation areas, listed buildings and flats always need an application, and the boundary wall usually brings in the Party Wall Act.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
Guide prices for Thame
Labour and material costs vary across the UK, so for Thame we use our South East England factor (×1.12). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Thame: £2,350 to £4,260 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £20,000 – £24,000 | £21,500 – £27,000 | £26,500 – £34,500 |
| 2 m × 5.5 m 11 m² | £25,500 – £31,000 | £29,500 – £37,000 | £36,500 – £47,000 |
| 2.2 m × 7 m 15 m² | £35,000 – £42,500 | £40,000 – £50,500 | £50,000 – £64,000 |
Try the guide-price tool to see a range for your own size and finish.
Covering Thame
Site visits are available across Thame (OX9). Nearby, we also take on projects in Oxford (12 miles), Bicester (13 miles), Henley-on-Thames (14 miles), Abingdon (14 miles).
In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
What is included
- New boundary wall or raised party wall
- Survey of the outrigger, boundary wall and drainage
- Design to keep daylight in the middle of the house
- Glazed, sloping or flat roof with rooflights
- Party wall notice support (England and Wales)
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 draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Questions people ask about side return extensions
Do I need building regulations approval in Thame?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Do you cover all of Thame?
Yes. We cover Thame and the surrounding parts of Oxfordshire. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Thame, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
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 £2,350 to £4,260 per m² including VAT, so a typical 2 m × 5.5 m infill lands around £29,500 to £37,000 at standard spec in Thame, more in London.
Book a free site visit in Thame
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.