Price guide

How much does an extension cost in the Cotswolds?

Short answer

A Gloucester builder publishes £1,700 to £2,500 per square metre for a standard extension, with Stroud at the lower end. An Oxford firm gives £2,800 to £3,500 for single-storey work. A national guide gives £2,200 to £3,300 plus VAT. Add fees for drawings, planning and building control. Get three written quotes.

Updated 15 October 2026 · 3 min read · 7 sources

What local builders publish

Local published prices for a standard extension run from about £1,700 to £2,500 per square metre. Most Cotswold builders do not publish prices. They quote after they see the drawings.

We found two firms near the Cotswolds that publish extension prices on their own websites. A square metre price usually covers the shell and a standard finish, not a kitchen.

Extension prices published by firms near the Cotswolds
Firm (base)	Job or area	Published price
Gloucester Building (Gloucester)	Standard extension, Stroud and Forest of Dean	£1,700 to £2,100 per m²
Gloucester Building (Gloucester)	Standard extension, Tewkesbury	£1,800 to £2,200 per m²
Gloucester Building (Gloucester)	Standard extension, Cheltenham	£2,000 to £2,500 per m²
Gloucester Building (Gloucester)	Single-storey rear, 4 m by 6 m (24 m²)	£43,200 to £60,000
Gloucester Building (Gloucester)	Two-storey, 4 m by 6 m (48 m² in total)	£86,400 to £120,000
Crawford Construction (Oxford)	Single-storey extension in Oxford	£2,800 to £3,500 per m²

Prices that each firm publishes on its own website, checked on 15 October 2026. Gloucester Building's page is dated 22 January 2026. Neither page says if VAT is included. These are guide prices, not quotes for your home. Sources: Gloucester Building (Gloucester): house extension costs, 2026 (22 January 2026), Crawford Construction (Oxford): loft conversion cost calculator, 2026.

National prices per square metre

A national guide gives a similar range for a standard finish, and more for a high finish. These are national figures, not Cotswold quotes. Use them to see if a quote is in a normal range.

National extension costs per square metre, excluding VAT
Type	Standard	Good	Excellent
Single-storey	£2,200 to £2,500	£2,500 to £2,900	£2,900 to £3,300
Two-storey	£2,000 to £2,400	£2,400 to £2,800	£2,800 to £3,200

National figures from Homebuilding & Renovating (updated 19 February 2026), excluding VAT, checked on 15 October 2026. They are not local prices. Sources: Homebuilding & Renovating: how much does an extension cost? (national, updated 19 February 2026).

Fees to add

Fees are not in the build price. These are the official fees, and one local firm’s figures for professional fees.

Fees for an extension
Fee	Amount	Source
Householder planning application, England	£548	Planning Portal, from 1 April 2026
Listed building consent application	No fee	Planning Portal
Building control, extension up to 20 m² (full plans)	£595 including VAT	Cotswold District Council, 2026/27
Building control, extension 20 to 60 m² (full plans)	£900 including VAT	Cotswold District Council, 2026/27
Architectural design	£1,500 to £4,000	Gloucester Building
Structural engineer	£500 to £1,200	Gloucester Building
Party wall agreement, per neighbour	£700 to £1,500	Gloucester Building

Official fees from the Planning Portal fee schedule and the Cotswold District Council fee schedule (20 March 2026). Professional fees published by Gloucester Building. All checked on 15 October 2026. Other councils and private approvers set their own building control fees. Sources: Planning Portal: Application fees, England, from 1 April 2026 (PDF), Cotswold District Council: Building control fees 2026/27 (PDF, 20 March 2026), Gloucester Building (Gloucester): house extension costs, 2026 (22 January 2026).

What makes an extension cost more in the Cotswolds

Natural Cotswold stone walls cost more than block and render. In a conservation area, the council often expects stone to match the house.

Planning rules can add cost. On designated land, a side extension or a two-storey rear extension needs planning permission, and drawings take longer.

A listed house needs listed building consent. The council may ask for traditional materials and details.

Ground conditions matter. Gloucester Building adds £2,000 to £5,000 for deeper foundations on clay soil.

Kitchens, flooring and glazing are often extra. Gloucester Building says a kitchen is not usually in a builder’s price.

How to get a fair price

Get written quotes from at least three builders, based on the same drawings.

Ask what the square metre price includes and leaves out.
Ask if VAT is included.
Ask for a fixed price, not a day rate.
Agree payment stages linked to work done.
Ask who deals with building control and party wall notices.

Questions

How much does a 4 by 6 metre extension cost?

One Gloucester builder publishes £43,200 to £60,000 for a 24 m² single-storey rear extension. Natural stone, a listed house or a high finish will cost more. Get written quotes.

Is a two-storey extension cheaper per square metre?

Usually, yes. The foundations and roof serve two floors. A national guide gives £2,000 to £2,400 per m² for a standard two-storey build, against £2,200 to £2,500 for single-storey.

Do extension prices include VAT?

Often not. The national figures above exclude VAT, and the local firms do not say. Ask each builder.