Two-storey side extensions in Oxfordshire

What a two-storey side extension involves

A two-storey side extension suits a detached or semi-detached house with a side garden, driveway or garage wide enough to build on. You get a design that sits comfortably on the street, a planning application or permitted development check depending on your nation, structural design, building regulations approval and the build itself. We manage the whole process, and the work is carried out by vetted teams working under S&K.

Oxfordshire towns we list: Oxford (OX1), Banbury (OX15), Abingdon (OX13), Bicester (OX6), Didcot (OX11) and Witney (OX7). Every other address in Oxfordshire is covered as well.

Guide price in South East England

For budgeting in Oxfordshire, allow around £94,500–£127,000 for a two-storey side extension with a 3 m × 7 m footprint on two floors (42 m² of new floor space). That's based on £2,260–£3,030 per m² including VAT for South East England. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.

Rules in England

In England, a two-storey side extension always needs householder planning permission, because permitted development only allows single-storey extensions beyond a side wall. The fee is £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Expect them to look at set-back, roof height, gaps to the boundary and the effect on neighbours.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Avoiding a terracing effect

Where semi-detached houses sit close together, side extensions on neighbouring houses can join up and turn a row of pairs into a terrace. Many councils ask for a gap to the boundary at first floor to stop this, so we check local guidance before fixing the width.

Side windows, boundaries and gutters

Upstairs windows in the side wall face the neighbour, so they are usually obscure-glazed and fixed, or left out. Building close to the boundary also raises questions about foundations, overhanging gutters and access for maintenance, so we design the eaves and gutter to stay within your land.

How we work in Oxfordshire

1. Free site visit

   We visit your home in Oxfordshire, look at the structure, access and boundaries, and talk through what you want the new rooms to do.

2. Get it approved

   Once you're happy with the design we submit it to the council for Oxfordshire and deal with any questions from the planning officer.

3. Detail and price

   Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.

4. On site

   One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Towns we cover in Oxfordshire

• Oxford
• Banbury
• Abingdon
• Bicester
• Didcot
• Witney
• Cowley
• Carterton
• Kidlington
• Wantage
• Wallingford
• Henley-on-Thames
• Thame

Neighbouring areas

• Two-storey side extensions in Buckinghamshire
• Two-storey side extensions in Berkshire
• Two-storey side extensions in Bedfordshire
• Two-storey side extensions in Hertfordshire

All extension services in Oxfordshire · About two-storey side extensions