Oxford, Oxfordshire
Semi-detached rear extension in Oxford
Single or two-storey extensions for semi-detached houses, with side access and one party wall. If you live in Oxford and want to know what a semi-detached rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Oxford sits in Oxfordshire, with postcode districts including OX1, OX2, OX3 and OX4. In Oxford we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Oxford?
A semi-detached rear extension in Oxford is priced at £2,130–£3,470 per square metre including VAT as a guide, before kitchen fit-out and fees. South East prices run above our West Midlands baseline, mainly on labour rates and clay-soil foundations.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £25,500–£41,500 |
| 4 m wide × 5 m deep (20 m²) | £42,500–£69,500 |
| 4 m wide × 6 m deep (24 m²) | £51,000–£83,500 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a semi-detached rear extension in Oxford?
Whether your semi-detached rear extension in Oxford needs a planning application depends on its size, your house and any local restrictions.
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Oxford like to extend?
Commuter semis and detached houses make up much of Oxford, and longer gardens make England's prior approval route for deeper rear extensions worth considering.
How a semi-detached rear extension in Oxford comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Semi-detached rear extensions near Oxford
Close by, we work in Cowley, about 2.5 miles away, and Kidlington, about 5.0 miles away.
- Semi-detached rear extension in Cowley
- Semi-detached rear extension in Kidlington
- Semi-detached rear extension in Abingdon
- Semi-detached rear extension in Didcot
- Semi-detached rear extension in Witney
Other work in Oxford:
FAQ
Semi-detached rear extension questions in Oxford
Can you match the brick or stone on my Oxford house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Is the site visit in Oxford free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do I need a party wall agreement?
Usually with the attached neighbour, in England and Wales.
Do you handle building control in Oxford?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
How long does a rear extension take to build in Oxford?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.