House extension prices for 2026
Our national guide rates run from about £1,750 to £3,400 per m² for a single-storey rear extension and £1,550 to £3,000 per m² for two-storey work, including VAT at 20%. A standard 4 m × 5 m single-storey extension is around £41,000 to £52,000. Regional factors adjust these for your area.
These are guide ranges for planning a budget, set against published 2026 cost guides, not quotes. They cover the build itself unless a table says otherwise; design, structural calculations, council fees, kitchens and decoration are extra. Your written price follows a survey and agreed drawings. Prices were last reviewed in October 2026.
The three specification tiers
- Essential: Simple shape, standard brick or render, flat roof with rooflights, standard doors and windows.
- Standard: Matched brickwork, roof lantern or several rooflights, wide sliding or bifold doors, quality finishes.
- Premium: Complex shape or structure, large-format glazing, cladding details, high-end finishes throughout.
Regional factors
| Region | Factor applied |
|---|---|
| London | ×1.3 |
| South East England | ×1.12 |
| East of England | ×1.06 |
| South West England | ×1.02 |
| West Midlands | ×0.97 |
| East Midlands | ×0.95 |
| North West England | ×0.95 |
| Yorkshire and the Humber | ×0.94 |
| North East England | ×0.91 |
| Wales | ×0.93 |
| Scotland | ×0.98 |
| Northern Ireland | ×0.86 |
Common extras
| Extra | Guide (national, inc VAT) |
|---|---|
| Wide sliding or bifold doors (3–4 m) | £4,500 – £9,500 |
| Roof lantern or extra rooflights | £2,000 – £5,500 |
| Mid-range kitchen, supplied and fitted | £9,000 – £20,000 |
| Wet underfloor heating to the new floor | £1,800 – £4,000 |
| Design pack: survey, planning and building regs drawings | £2,200 – £3,800 |
Council fees in England (from 1 April 2026)
- Householder planning application: £548
- Lawful development certificate (proposed extension): £274
- Larger home extension prior approval: £249
Fees in Wales, Scotland and Northern Ireland are set by each government. Building control charges are set by your council or building control approver.
Guide prices by extension type
National figures, before the regional factor. The middle column is our Standard specification.
Single-storey rear extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £21,000 – £25,000 | £24,500 – £31,500 | £31,000 – £41,000 |
| 4 m × 5 m 20 m² | £35,000 – £41,000 | £41,000 – £52,000 | £52,000 – £68,000 |
| 5 m × 6 m 30 m² | £52,500 – £61,500 | £61,500 – £78,000 | £78,000 – £102,000 |
Double-storey extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £38,000 – £45,500 | £43,000 – £56,500 | £55,000 – £72,000 |
| 4 m × 4 m, two floors 32 m² | £49,500 – £59,500 | £57,500 – £75,500 | £73,500 – £96,000 |
| 4 m × 6 m, two floors 48 m² | £74,000 – £89,000 | £86,000 – £113,000 | £110,000 – £144,000 |
Side return extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £18,000 – £21,500 | £19,000 – £24,000 | £24,000 – £30,500 |
| 2 m × 5.5 m 11 m² | £23,000 – £27,500 | £26,000 – £33,000 | £33,000 – £42,000 |
| 2.2 m × 7 m 15 m² | £31,500 – £37,500 | £36,000 – £45,000 | £45,000 – £57,000 |
Wraparound extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Compact L-shape 18 m² | £36,000 – £43,500 | £41,000 – £52,500 | £52,000 – £67,000 |
| Medium L-shape 25 m² | £50,000 – £60,000 | £57,500 – £72,500 | £72,500 – £92,500 |
| Large L-shape 32 m² | £64,000 – £77,000 | £73,500 – £93,000 | £92,500 – £118,500 |
Side extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £22,000 – £26,500 | £24,500 – £32,000 | £31,000 – £41,000 |
| 3 m × 6 m 18 m² | £31,500 – £38,000 | £36,500 – £48,000 | £46,500 – £61,500 |
| 3 m × 8 m 24 m² | £42,000 – £50,500 | £49,000 – £64,000 | £62,000 – £82,000 |
Extensions over a garage
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £24,000 – £29,500 | £25,000 – £32,500 | £32,000 – £41,000 |
| Over a large single garage 16 m² | £28,500 – £35,500 | £33,500 – £43,500 | £43,000 – £54,500 |
| Over a double garage 24 m² | £43,000 – £53,000 | £50,000 – £65,000 | £64,500 – £82,000 |
Kitchen extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 5 m 15 m² | £27,000 – £31,500 | £31,500 – £40,000 | £39,500 – £52,500 |
| 4 m × 5 m 20 m² | £36,000 – £42,000 | £42,000 – £53,000 | £53,000 – £70,000 |
| 4 m × 7 m 28 m² | £50,000 – £59,000 | £58,500 – £74,500 | £74,000 – £98,000 |
Build cost only. A mid-range kitchen, supplied and fitted, typically adds £9,000 to £20,000.
Bedroom extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| One bedroom 12 m² | £26,000 – £32,000 | £26,000 – £34,000 | £28,500 – £38,500 |
| Bedroom and en-suite 18 m² | £28,500 – £35,500 | £34,000 – £44,500 | £43,000 – £58,000 |
| Two rooms 30 m² | £48,000 – £58,500 | £57,000 – £73,500 | £72,000 – £96,000 |
Utility and boot room extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2 m × 2.5 m 5 m² | £14,000 – £17,000 | £14,000 – £17,500 | £14,000 – £17,500 |
| 2.5 m × 3.2 m 8 m² | £15,000 – £18,000 | £18,000 – £22,500 | £22,000 – £28,000 |
| 3 m × 3.6 m 11 m² | £20,500 – £25,000 | £24,500 – £31,000 | £30,500 – £38,500 |
Home office extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 3.2 m 8 m² | £16,000 – £19,500 | £17,000 – £22,000 | £21,500 – £27,500 |
| 3 m × 3.6 m 11 m² | £20,000 – £24,500 | £23,500 – £30,000 | £29,500 – £37,500 |
| 3 m × 5 m 15 m² | £27,500 – £33,000 | £32,000 – £40,500 | £40,500 – £51,000 |
Annexe extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £55,000 – £69,000 | £60,000 – £75,000 | £75,000 – £95,000 |
| One-bedroom annexe 35 m² | £70,000 – £87,500 | £84,000 – £105,000 | £105,000 – £133,000 |
| Larger annexe 45 m² | £90,000 – £112,500 | £108,000 – £135,000 | £135,000 – £171,000 |
Porch extensions
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Small brick or glazed porch, up to 3 m² | £4,000 – £6,500 |
| Standard | Brick porch with tiled roof and composite door | £6,000 – £9,500 |
| Premium | Larger porch with WC or oak frame and premium glazing | £9,000 – £15,000 |
Orangery extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £30,000 – £36,500 | £33,500 – £42,000 | £40,500 – £54,000 |
| 4 m × 4 m 16 m² | £38,000 – £46,500 | £44,500 – £56,000 | £54,000 – £72,000 |
| 4 m × 6 m 24 m² | £57,500 – £70,000 | £67,000 – £84,000 | £81,500 – £108,000 |
Glass box extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2 m × 4 m 8 m² | £30,000 – £36,000 | £30,000 – £38,000 | £34,000 – £46,500 |
| 3 m × 4 m 12 m² | £36,000 – £43,500 | £42,000 – £53,000 | £51,500 – £70,000 |
| 3 m × 6 m 18 m² | £54,000 – £65,000 | £63,000 – £79,500 | £77,000 – £104,500 |
Flat roof extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £21,000 – £25,000 | £24,500 – £31,500 | £31,000 – £40,500 |
| 4 m × 5 m 20 m² | £35,000 – £41,000 | £41,000 – £52,000 | £52,000 – £67,000 |
| 5 m × 6 m 30 m² | £52,500 – £61,500 | £61,500 – £78,000 | £78,000 – £100,500 |
Pitched roof extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £22,000 – £26,000 | £25,500 – £33,000 | £33,000 – £42,000 |
| 4 m × 5 m 20 m² | £37,000 – £43,000 | £43,000 – £55,000 | £55,000 – £70,000 |
| 5 m × 6 m 30 m² | £55,500 – £64,500 | £64,500 – £82,500 | £82,500 – £105,000 |
Timber frame extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £21,000 – £25,500 | £24,500 – £32,000 | £31,000 – £41,000 |
| 4 m × 5 m 20 m² | £35,000 – £42,000 | £41,000 – £53,000 | £52,000 – £68,000 |
| 5 m × 6 m 30 m² | £52,500 – £63,000 | £61,500 – £79,500 | £78,000 – £102,000 |
Bungalow extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 5 m 15 m² | £26,000 – £31,500 | £30,500 – £40,000 | £39,000 – £51,000 |
| 4 m × 6 m 24 m² | £42,000 – £50,500 | £49,000 – £64,000 | £62,000 – £82,000 |
| L-shape 35 m² | £61,000 – £73,500 | £71,500 – £93,000 | £91,000 – £119,000 |
Conservatory replacement extensions
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 3.3 m 10 m² | £20,000 – £24,000 | £21,500 – £27,500 | £27,500 – £35,000 |
| 3.5 m × 4 m 14 m² | £25,500 – £31,000 | £30,000 – £38,500 | £38,500 – £49,000 |
| 4 m × 5 m 20 m² | £37,000 – £44,000 | £43,000 – £55,000 | £55,000 – £70,000 |
Includes removal of the old conservatory. Reusing existing foundations is only possible after investigation.
Extension plans and drawings
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Measured survey and planning drawings | £1,200 – £2,200 |
| Standard | Planning drawings plus building regulations drawings | £2,200 – £3,800 |
| Premium | Full pack with structural calculations and 3D visuals | £3,400 – £5,500 |
Planning permission for extensions
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Permitted development confirmed in writing (certificate or notification) | £350 – £650 |
| Standard | Householder planning application handled | £600 – £1,100 |
| Premium | Application with heritage or design statements, and responses to the council | £900 – £1,600 |
Our handling fee only. Council fees are extra: in England from 1 April 2026 a householder application is £548, a lawful development certificate for a proposed extension £274 and a larger home extension prior approval £249. Drawings are priced separately.
Building regulations for extensions
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Building regulations drawings for a simple single-storey extension | £900 – £1,800 |
| Standard | Drawings plus structural calculations | £1,300 – £2,600 |
| Premium | Complex or two-storey pack with energy calculations | £2,200 – £3,800 |
Our design fee only. Building control charges are set by your council (or, in England and Wales, a registered building control approver) and quoted separately.