Didcot, Oxfordshire
Semi-detached rear extension in Didcot
We plan and build rear extensions for semi-detached houses for homeowners in Didcot. Single or two-storey extensions for semi-detached houses, with side access and one party wall. Start with a free site visit, then a written price once the design is agreed.
Didcot and its postcode districts OX11 are part of our Oxfordshire coverage. In Didcot 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 Didcot?
In Didcot, our guide for a semi-detached rear extension is £2,130–£3,470 per square metre including VAT for a standard specification. 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 Didcot?
Planning for a semi-detached rear extension in Didcot follows the English householder rules.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres 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. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Didcot like to extend?
Commuter semis and detached houses make up much of Didcot, and longer gardens make England's prior approval route for deeper rear extensions worth considering.
How a semi-detached rear extension in Didcot comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Semi-detached rear extensions near Didcot
Neighbouring places we cover include Abingdon (4.6 miles) and Wallingford (5.1 miles).
- Semi-detached rear extension in Abingdon
- Semi-detached rear extension in Wallingford
- Semi-detached rear extension in Wantage
- Semi-detached rear extension in Cowley
- Semi-detached rear extension in Oxford
Other work in Didcot:
FAQ
Semi-detached rear extension questions in Didcot
Do you handle building control in Didcot?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
How far can I extend a semi without planning?
3 metres under permitted development in England, or up to 6 metres with prior approval, outside designated land.
How long does a rear extension take to build in Didcot?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
What postcode areas do you cover around Didcot?
Including OX11, and the surrounding Oxfordshire area.
Is the site visit in Didcot free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.