Two-storey side extensions in Gloucestershire

What a two-storey side extension involves

A two-storey side extension is a new two-floor addition built into the space beside your house, often over a driveway or side passage. It typically adds one or two bedrooms upstairs and a utility, study or larger kitchen below, without giving up rear garden.

The main places we list in Gloucestershire are Gloucester (GL1), Cheltenham (GL50), Stroud (GL5), Kingswood (BS15), Mangotsfield (BS16) and Yate (BS37). We cover the villages in between too.

Guide price in South West England

For budgeting in Gloucestershire, allow around £88,500–£119,000 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 £2,110–£2,830 per m² including VAT for South West England. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.

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 Gloucestershire

1. Free site visit

   We visit your home in Gloucestershire, 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 Gloucestershire and deal with any questions from the planning officer.

3. Engineer it

   Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.

4. Finish and certify

   Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Towns we cover in Gloucestershire

• Gloucester
• Cheltenham
• Stroud
• Kingswood
• Mangotsfield
• Yate
• Tewkesbury
• Cirencester
• Dursley
• Bishops Cleeve
• Stoke Gifford
• Churchdown
• Cinderford
• Charlton Kings
• Thornbury

Neighbouring areas

• Two-storey side extensions in Bristol
• Two-storey side extensions in Wiltshire
• Two-storey side extensions in Herefordshire
• Two-storey side extensions in Gwent

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