Annexe extensions in Abingdon
Our design and build teams take on annexe extensions in Abingdon, from the first measured survey through planning and building control to the finished room.
- Guide price in AbingdonFrom £61,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsOX14

Is an annexe extension right for your house?
- Multi-generational families
- Relatives who need support close by
- Homes with a large side or rear garden
Accessibility is cheaper to design in than to retrofit. Level access, a 900 mm door width, a level-access shower and space to turn a wheelchair can all be planned into the footprint for little extra cost.
What should I budget for an annexe extension in Abingdon?
These guide figures apply our South East England adjustment (×1.12) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Abingdon: £2,240 to £4,260 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £61,500 – £77,500 | £67,000 – £84,500 | £84,000 – £106,500 |
| One-bedroom annexe 35 m² | £78,000 – £98,500 | £94,000 – £118,000 | £117,500 – £149,000 |
| Larger annexe 45 m² | £100,500 – £126,500 | £120,500 – £151,500 | £151,000 – £192,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
Planning and approvals in Abingdon
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
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 over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
Local to Abingdon
We cover Abingdon and the postcode districts OX14. We also work in nearby Didcot (5 miles), Oxford (6 miles), Wantage (8 miles), Witney (12 miles).
The South East has a broad mix of 1930s semis, post-war estates, newer developments and period cottages, and many houses have enough garden for a generous rear extension.
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 Abingdon home, measure up, talk through what you want and check the planning position.
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
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Your questions about an annexe extension in Abingdon
Do I need building regulations approval in Abingdon?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
How long does an annexe extension take to build in Abingdon?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
Do you cover all of Abingdon?
Yes. We cover Abingdon and the surrounding parts of Oxfordshire. Site visits are free and there is no obligation.
Can the annexe have its own front door?
Yes, many do, but it should still connect to the main house to stay clearly part of it.
Will an annexe affect council tax?
It can. Some annexes are assessed separately for council tax, with discounts or exemptions in some cases when occupied by a relative. Check with the Valuation Office Agency (England and Wales), your local assessor (Scotland) or Land & Property Services (Northern Ireland).
Book a free site visit in Abingdon
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.