Estiquote

Local costs · South East · September 2026

How much does an extension cost in Winchester?

A mid-range 25 m² single-storey extension in Winchester costs about £72,500 to £89,500 including VAT, or £2,900 to £3,600 per m² at South East prices. Winchester charges £1,085 for building control on a 10 to 40 m² extension (building notice, including VAT). With design, a structural engineer, building control and a 15% contingency, budget £89,500 to £115,000.

By Estiquote · Prices reviewed · Council fees from Winchester's published schedule · How we calculate

Work out your project in Winchester

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Typical prices in Winchester

Mid-range finish, South East prices, including VAT. The budget adds design and engineering fees, Winchester's building control charge and a 15% contingency.
ProjectBuilding workBudget to plan for
Single-storey extension, 25 m²£72,500 to £89,500£89,500 to £115,000
Double-storey extension, 40 m²£105,000 to £132,000£128,000 to £167,000
Dormer loft conversion, 30 m²£65,000 to £80,000£80,000 to £102,000
Kitchen, medium£9,700 to £17,200£11,100 to £19,800
Bathroom refit£6,500 to £9,800£7,500 to £11,300

Building prices in South East run about 15% above the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.

Building control fees in Winchester

Winchester council charges including VAT (plan and inspection combined)
WorkCharge
Extension up to 10 m² (full plans)Not published
Extension 10 to 40 m² (full plans)Not published
Larger extension, over 40 m² (full plans)Not published
Extension 10 to 40 m² (building notice)£1,085
Loft conversion up to 40 m²£1,020
Garage conversion£615

Winchester charges £1,085 for building control on a 10 to 40 m² extension (building notice, including VAT). Source: Winchester's building control charges, 2026/27. Inc VAT ("Fees include VAT if applicable").

Check before relying on it: the council publishes building notice charges only.

Private approved inspectors set their own prices and are often competitive, so it is worth asking one or two for a quote as well. See how Winchester compares with every council we checked.

Notes on Winchester's schedule

Own schedule. Only building-notice charges are published; full plans = GBP250 deposit plus balance invoiced, total not stated. Loft (with dormer; 885 without) and garage figures are building-notice charges.

Planning

If your extension needs planning permission, a householder application in England costs £548. Many single-storey rear extensions are permitted development and need no application, and a lawful development certificate (£274) confirms it.

Other councils in South East

Building control for a 10 to 40 m² extension:

Questions people ask

How much does an extension cost in Winchester?

A mid-range 25 m² single-storey extension in Winchester costs about £72,500 to £89,500 including VAT for the building work, or £2,900 to £3,600 per m², based on South East prices reviewed in September 2026. With fees and a 15% contingency, budget £89,500 to £115,000.

How much is building control in Winchester?

Winchester charges £1,085 (including VAT) for a 10 to 40 m² extension (building notice), according to its published schedule (2026/27).

How much does a loft conversion cost in Winchester?

A mid-range 30 m² dormer loft conversion in Winchester costs about £65,000 to £80,000 including VAT for the building work, and about £80,000 to £102,000 with fees and a 15% contingency.

Before you get quotes