2026 Oxfordshire cost guide

How much does a house extension cost in Oxfordshire?

A useful first budget needs more than a price per square metre. Structure, access, kitchen work, glazing and how much of the existing house changes can move the total quickly.

Illustrative homeowner range

£76,000–£99,000

a 30 m² standard-finish rear extension, including VAT where charged.

Standard finishOX postcode basis14–27 weeks typical programme

This is a rounded early example from Proper Job pricing model v14, not a quotation or a promise of local availability. Your range should use the actual property, size, scope, access and choices.

Price my house extensionHow Proper Job works

What moves the price

  • Single-storey, two-storey, side-return or wraparound form
  • Ground conditions, drainage moves and structural steel
  • Kitchen, utility and knock-through work inside the existing house
  • Glazing, rooflights, doors and finish level
  • Restricted access, parking, neighbours and working-hour limits

What this example allows for

  • A ballpark-stage allowance for a rear extension shell and standard domestic finish
  • Typical Oxfordshire regional pricing pressure
  • A contractor margin and a wider range for early unknowns
  • VAT added for the homeowner-facing example where it is charged

Before you ask builders for quotes

  1. Confirm the extension footprint and whether the kitchen is part of the works
  2. Identify drainage, party-wall, access and planning constraints
  3. Separate supply items such as the kitchen, glazing and flooring
  4. Ask builders to price the same drawings, specification and exclusions

Questions homeowners ask

Is this a quotation?

No. It is an early budget example from Proper Job’s current pricing model. A builder still needs drawings, site information and a defined specification for a firm quotation.

Does the size alone decide the cost?

No. Size is only one driver. Structure, existing-house alterations, access, finish, services and supply items can matter just as much.

Should I include VAT in my budget?

Usually, yes. The example shown here includes 20% VAT, but the final treatment depends on the contractor and the work.

Use your project, not the example

Add the real size, finish, logistics and likely extras. Your first Proper Job guide is free.

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Other homeowner cost guides

Loft conversion£77,000–£100,000Kitchen renovation£25,000–£33,000Bathroom renovation£12,000–£16,000

Pricing example checked 17 July 2026.