Two-Storey Extension Cost 2026: UK Guide Prices

Updated 9 November 2026 · Written by the Two Storey Extensions team

Short answer: A two-storey extension typically costs £2,000–£2,700 per m² of new floor area in 2026, including VAT, which puts a 28 m² rear extension at about £56,000–£75,500. These guide prices assume a Standard specification at West Midlands prices; side, wraparound and front extensions cost more per m², and London and the South East cost more overall. Professional fees, planning fees and a contingency of around 10% come on top.

How much does each type of two-storey extension cost per m²?

Our guide prices are per m² of new floor area, counting both storeys. For example, a typical rear extension has a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). All figures include VAT at 20% and assume a Standard specification at West Midlands prices, built to a finish ready for decoration.

Type	Guide price per m²	Typical size	Typical total
Two-storey rear extension	£2,000–£2,700 per m²	28 m²	£56,000–£75,500
Two-storey side extension	£2,050–£2,750 per m²	42 m²	£86,000–£115,500
Two-storey wraparound extension	£2,150–£2,950 per m²	56 m²	£120,500–£165,000
Part single, part two-storey	£2,000–£2,750 per m²	36 m²	£72,000–£99,000
Extension over a garage	£1,750–£2,550 per m²	18 m²	£31,500–£46,000
First-floor extension over an existing single storey	£1,800–£2,600 per m²	14 m²	£25,000–£36,500
Two-storey front extension	£2,200–£3,000 per m²	12 m²	£26,500–£36,000

Smaller extensions tend to cost more per m², because scaffolding, the roof and the connection to the house are spread over less floor area. Building over a garage or an existing single storey costs less per m² because part of the structure already exists.

How much does a two-storey extension cost in my region?

Building costs vary across the UK with labour rates, material deliveries and demand for trades. The table applies our regional factors to the same 28 m² two-storey rear extension at Standard specification, including VAT.

Region	Guide price per m²	Typical total (28 m²)
London	£2,400–£3,240 per m²	£67,000–£90,500
South East England	£2,200–£2,970 per m²	£61,500–£83,000
East of England	£2,060–£2,780 per m²	£57,500–£78,000
South West England	£2,060–£2,780 per m²	£57,500–£78,000
West Midlands	£2,000–£2,700 per m²	£56,000–£75,500
East Midlands	£1,960–£2,650 per m²	£55,000–£74,000
North West England	£1,900–£2,560 per m²	£53,000–£72,000
Yorkshire and the Humber	£1,840–£2,480 per m²	£51,500–£69,500
North East England	£1,800–£2,430 per m²	£50,500–£68,000
Wales	£1,840–£2,480 per m²	£51,500–£69,500
Scotland	£1,880–£2,540 per m²	£52,500–£71,000
Northern Ireland	£1,760–£2,380 per m²	£49,500–£66,500

Prices also vary within each region, between city centres and rural areas, and with access, parking and how busy local builders are. Use the range for budgeting, not as a quote.

How does the specification change the price?

The specification you choose moves the price almost as much as the size. We use three tiers. The totals below are for the same rear extension at West Midlands prices, including VAT.

Specification	What it usually means	Typical total (rear)
Essential	Good-quality standard finishes, matching brick or render, uPVC windows.	£51,500–£69,500
Standard	Our usual spec: matching materials, aluminium or high-grade uPVC glazing, upgraded insulation.	£56,000–£75,500
Premium	Larger glazing, architectural finishes, more structural steel and higher-spec fittings.	£67,000–£90,500

Large areas of glazing, vaulted ceilings, render or cladding systems and open-plan layouts that need extra steel all push a project towards Premium. Kitchens, bathroom sanitaryware and flooring sit outside these figures whichever tier you choose, so budget for them separately.

What extras should I budget for?

Some items are common on two-storey extensions but vary so much that we price them as extras. Guide ranges, including VAT:

En-suite shower room upstairs: £5,500–£11,000
Large sliding or bi-fold doors: £4,000–£9,000
Juliet balcony: £1,200–£2,500
Underfloor heating (ground floor): £1,500–£3,500
Wide open-plan opening into the house: £3,000–£7,000

Other costs that sometimes appear are moving a drain or manhole, a larger boiler to serve extra radiators, moving a gas or electricity meter, and deeper foundations if trial holes find clay, tree roots or made-up ground. Ask for each to be listed separately in any quote so you can compare like with like.

What professional fees should I allow for?

Professional fees sit on top of the build price. Most two-storey extensions need planning drawings, building regulations drawings, a structural engineer and building control. Guide ranges, including VAT unless marked otherwise:

Service	Guide range
Planning drawings (survey and design)	£2,000–£3,500
Building regulations drawings and specification	£1,500–£4,000
Structural engineer (calculations and beam design)	£750–£2,200
Building control or building warrant fee	£800–£1,900
Party wall surveyor, one agreed surveyor (England and Wales only)	£1,300–£1,500 plus VAT

Party wall costs only arise in England and Wales, where the Party Wall etc. Act 1996 applies, and only if your work affects a shared wall or involves digging near a neighbour's foundations. If you and your neighbour each appoint a surveyor, the cost is higher. Check whether a quote already includes any of these fees so you do not count them twice.

How much are planning fees in England, Wales, Scotland and Northern Ireland?

Planning application fees are set nationally and differ in each part of the UK. These are the householder fees for an extension to one house:

Nation	Householder application fee	Usual decision period
England	£548 (or £575 for applications made from 8 December 2026)	8 weeks from validation
Wales	£585	Normally 8 weeks
Scotland	£371	Two months
Northern Ireland	£347	Councils target an average of 15 weeks

If your extension falls within permitted development, there is no planning application fee, but a certificate confirming it is lawful is worth having. In England, a lawful development certificate for a proposed extension costs £274 (about £288 for applications from 8 December 2026). Building control fees are separate and are set by each council or approver.

What does the guide price include, and how much contingency should I keep?

Our guide prices cover the build to a finish ready for decoration: foundations and structure, the roof, windows and external doors, electrics, plumbing first and second fix, plastering, and making good where the extension meets the house. They include VAT at 20%.

They do not include kitchens, bathroom sanitaryware (except the en-suite extra), flooring, decorating, professional fees, or planning and building control fees. Keep a contingency of around 10% of the build cost for things nobody can see until work starts, such as poor ground, hidden drains or defects in the existing structure. These are guide prices, not quotes: a firm price needs a site visit and an agreed design.

Questions about this topic

Is a two-storey extension cheaper per m² than a single-storey one?

It often is. The foundations and roof are among the most expensive parts of any extension, and on a two-storey extension they serve twice the floor area. The total cost is higher, but each m² of new space tends to cost less than the same space built on one floor. We do not publish single-storey prices on this site.

Do the guide prices include VAT?

Yes. All our guide prices include VAT at 20%, which applies to most building work on an existing home. The only figure shown without VAT is the party wall surveyor's fee, which is listed plus VAT. When you compare quotes, ask each builder to confirm in writing whether VAT is included.

Why does a two-storey extension cost more in London?

Labour, deliveries, parking, skip permits and restricted access all cost more in London, so our London figures are about 20% above the West Midlands baseline. A 28 m² rear extension at Standard specification has a London guide price of £67,000–£90,500, including VAT at 20%.

How accurate is a guide price for a two-storey extension?

A guide price helps you decide whether a project is affordable, but it cannot allow for your ground conditions, access, drainage, the condition of the existing house or your exact design. Treat it as a budgeting range. A firm price needs a site visit, a measured survey and agreed drawings.

Sources

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