the North West cost guide

Extension costs in the North West (2026): prices by area

Updated October 2026Prices include VAT and fees

Quick answerA 20m² single storey rear extension in the North West typically costs £52,000 to £62,500 including VAT. South Manchester, Stockport and Cheshire price highest, Blackpool, Blackburn and Oldham lowest. Demand in the Cheshire commuter belt is the main reason prices vary so much within the region.

Typical prices in the North West

the North West the North West, North Westindex 0.99

Single storey rear extension20 m² (5m × 4m)£52,000 to £62,500£2,840/m²
Kitchen extension with bifolds24 m² (6m × 4m), mid spec£69,500 to £83,000£3,150/m²
Double storey rear extension40 m² over two floors£84,000 to £100,500£2,280/m²
Dormer loft conversion2 bedrooms + en-suite£47,000 to £57,000
Velux loft conversion2 rooms£33,500 to £41,000
Garage conversion15 m² single garage£19,000 to £23,000£1,390/m²

All prices include 20% VAT, professional fees and statutory planning fees. Kitchen extension includes a mid-range kitchen, bifolds and a roof lantern.

Price my exact project

Building in the North West

The North West stretches from Cheshire's large detached houses to the terraced streets of the Lancashire mill towns, and building costs vary with them. Manchester's southern suburbs, Stockport, Wilmslow and Knutsford attract strong demand and higher quotes, while Blackpool, Blackburn, Oldham and Wigan are some of the most affordable places in England to extend. Liverpool and Preston sit in between. Cumbria adds rural and lakeland sites with their own challenges.

What moves the price in the North West

Cheshire and south Manchester demand

Areas such as Didsbury, Bramhall, Wilmslow and Knutsford have larger homes and buyers willing to spend on big kitchen extensions. Builders there are busy and price accordingly, so expect quotes towards the top of the regional range.

Mill town terraces

Lancashire and Greater Manchester towns have long rows of stone and brick terraces with small back yards. Extensions are often compact and access can be through the house or a back alley, which keeps total costs down but adds labour per square metre.

Wet weather

The North West's rainfall affects build programmes. Builders allow for lost days and may tent the work or use faster-drying methods, and good drainage and damp detailing matter more than in drier parts of the country.

Planning and building control in the North West

Standard English rules apply. Many single storey rear extensions and lofts are permitted development within the usual limits. The Lake District National Park and conservation areas in town centres and villages restrict those rights, and some councils use Article 4 directions on stone terraces. Building Regulations approval is required for every extension. Check with your council before you commission drawings.

Prices across the North West

A 20m² single storey rear extension and a two-bedroom dormer loft with an en-suite, priced for each example postcode. All figures include VAT and fees.

Postcode	Area	Single storey, 20m²	Dormer loft	Index
M20	Manchester	£53,000 to £63,000	£47,500 to £58,000	1.00
CH2	Chester	£54,000 to £64,500	£48,500 to £59,000	1.02
L18	Liverpool	£50,000 to £60,000	£45,000 to £55,000	0.95

Cost index for every postcode area in the North West

Our index against the West Midlands base of 1.00. Higher means dearer. Enter a full postcode in the checker for district-level detail where we have it.

Area	Main town	Index
BB	Blackburn	0.93
BL	Bolton	0.95
CA	Carlisle	0.99
CH	Chester	1.02
CW	Crewe	0.98
FY	Blackpool	0.92
L	Liverpool	0.95
LA	Lancaster	0.97
M	Manchester	1.00
OL	Oldham	0.94
PR	Preston	0.96
SK	Stockport	1.02
WA	Warrington	1.00
WN	Wigan	0.94

the North West: common questions

How much does an extension cost in Manchester?

A 20m² single storey rear extension in Greater Manchester typically costs £52,000 to £62,500 including VAT, with south Manchester and Stockport at the upper end. A mid-spec 24m² kitchen extension with bifolds is around £69,500 to £83,000.

Is it cheaper to extend in Liverpool than Manchester?

Usually a little. Liverpool postcodes price slightly below Manchester on our index, although the most sought-after suburbs in both cities are closer together. Your own postcode gives a more accurate figure than the city average.

How much is a loft conversion in the North West?

A dormer loft conversion with two bedrooms and an en-suite typically costs £47,000 to £57,000 including VAT. On terraced houses, a rear dormer is the most common choice because it adds the most headroom within permitted development limits.

Do I need planning to extend a stone terrace?

Often not for a modest rear extension, but check first. Stone terraces are frequently in conservation areas, and some councils have removed permitted development rights with Article 4 directions. Your council's planning team or a lawful development certificate will confirm it.