Free · Instant · No sign-up
Renovation cost calculator
Choose your project, size, finish and postcode. You get a UK price range with VAT, fees and a contingency, based on prices reviewed in September 2026.
Loading the calculator…
UK renovation prices at a glance
In September 2026 a 25 m² single-storey rear extension costs £63,500 to £78,000 including VAT for a home outside London, or £77,500 to £98,500 once design, building control and a 15% contingency are added. In London the same extension costs £86,000 to £105,000 to build.
Every figure below comes from the same cost model as the calculator above: a typical home outside London, mid-range finish, VAT included. The right-hand column adds design, building control and other fees that usually apply, plus a 15% contingency (10% for a boiler, unvented cylinder, heat pump or windows, which are usually fixed prices). Use the calculator for your own size, finish and postcode.
| Project and type | Building work | Budget to plan for, with fees and contingency |
|---|---|---|
| House extension: single-storey rear (25 m²) | £63,500 to £78,000 | £77,500 to £98,500 |
| House extension: double-storey (40 m²) | £91,000 to £115,000 | £110,000 to £143,000 |
| House extension: wraparound or side return (30 m²) | £83,000 to £104,000 | £100,000 to £129,000 |
| Loft conversion: rooflight (Velux), 30 m² | £27,000 to £35,000 | £35,000 to £49,000 |
| Loft conversion: rear dormer (30 m²) | £47,000 to £58,000 | £58,000 to £75,500 |
| Loft conversion: l-shaped dormer (30 m²) | £55,000 to £68,000 | £67,000 to £87,000 |
| Loft conversion: hip-to-gable (with rear dormer), 30 m² | £55,000 to £68,000 | £67,000 to £87,000 |
| Loft conversion: double hip-to-gable (with rear dormer), 30 m² | £63,000 to £78,000 | £76,500 to £98,500 |
| Loft conversion: mansard (30 m²) | £65,000 to £85,000 | £78,500 to £106,000 |
| New kitchen: supply and fit (medium) | £9,000 to £16,000 | £10,400 to £18,400 |
| Bathroom: full bathroom refit, same layout | £6,000 to £9,000 | £6,900 to £10,400 |
| Bathroom: new en-suite | £7,000 to £10,500 | £8,000 to £12,100 |
| Bathroom: wet room | £7,500 to £11,000 | £8,600 to £12,700 |
| Bathroom: downstairs toilet | £2,800 to £4,000 | £3,200 to £4,600 |
| Bathroom: new downstairs wet room (no bathroom now) | £10,000 to £15,500 | £11,500 to £17,800 |
| Garage conversion: integral or attached single garage | £14,400 to £20,500 | £18,200 to £27,000 |
| Garage conversion: detached single garage | £21,500 to £30,000 | £26,500 to £38,000 |
| Whole-house renovation: full renovation (rewire, heating, kitchen, bathroom, plaster), 90 m² | £86,500 to £130,000 | £99,500 to £149,000 |
| New build house: built by a main contractor (140 m²) | £322,000 to £406,000 no VAT on new homes | £370,000 to £467,000 |
| House rewire: 1-bed flat | £3,300 to £4,200 | £3,800 to £4,800 |
| House rewire: 2-bed house | £4,200 to £5,300 | £4,900 to £6,000 |
| House rewire: 3-bed house | £5,400 to £7,200 | £6,200 to £8,200 |
| House rewire: 4-bed house | £7,100 to £8,800 | £8,100 to £10,100 |
| New consumer unit (fuse board): dual RCD board (Basic) | £550 to £800 | £630 to £920 |
| New consumer unit (fuse board): rCBO board (Standard) | £650 to £1,000 | £750 to £1,100 |
| EV charger installation: 7 kW smart charger, standard installation | £850 to £1,300 | £980 to £1,500 |
| Electrical safety report (EICR): studio or 1-bed flat | £100 to £180 | £110 to £210 |
| Electrical safety report (EICR): 2 or 3-bed house | £150 to £250 | £170 to £290 |
| Electrical safety report (EICR): 4-bed house | £250 to £350 | £290 to £400 |
| New roof: pitched roof, terraced house | £7,500 to £10,000 | £8,600 to £11,500 |
| New roof: pitched roof, semi-detached house | £10,500 to £14,000 | £12,100 to £16,100 |
| New roof: pitched roof, detached house | £15,000 to £21,000 | £17,300 to £24,000 |
| New roof: flat roof (20 m²) | £1,800 to £2,800 | £2,100 to £3,200 |
| Knock-through with steel beam: up to 2 m | £1,800 to £3,000 | £2,100 to £3,500 |
| Knock-through with steel beam: 3 to 4 m | £3,000 to £5,400 | £3,500 to £6,200 |
| Knock-through with steel beam: wider than 4 m or complex | £5,400 to £8,400 | £6,200 to £9,700 |
| New boiler: combi boiler, like-for-like swap | £2,500 to £3,200 | £2,700 to £3,500 |
| New boiler: system boiler to a combi | £3,200 to £4,200 | £3,500 to £4,600 |
| New boiler: regular boiler to a combi | £3,700 to £5,000 | £4,100 to £5,500 |
| New boiler: system or regular boiler swap, keeping the cylinder | £2,700 to £3,500 | £3,000 to £3,900 |
| New boiler: oil boiler, regular or system, like-for-like | £3,000 to £4,500 | £3,300 to £5,000 |
| New boiler: oil combi boiler, like-for-like | £4,000 to £5,500 | £4,400 to £6,000 |
| Unvented cylinder replacement: unvented cylinder, like-for-like | £1,400 to £2,200 | £1,600 to £2,400 |
| Air source heat pump: 2-bed home | £10,000 to £12,000 0% VAT before £7,500 grant | £11,000 to £13,200 |
| Air source heat pump: 3-bed home | £12,000 to £15,000 0% VAT before £7,500 grant | £13,200 to £16,500 |
| Air source heat pump: 4-bed home or larger | £15,000 to £18,000 0% VAT before £7,500 grant | £16,500 to £19,800 |
| Replacement windows: 2-bed house (about 7 windows) | £3,900 to £5,300 | £4,200 to £5,800 |
| Replacement windows: 3-bed semi (about 10 windows) | £5,500 to £7,500 | £6,000 to £8,300 |
| Replacement windows: 4-bed house (about 13 windows) | £7,100 to £9,700 | £7,900 to £10,700 |
How prices change by region
Labour and materials cost more in London and the South East and less in the North, Wales and Northern Ireland. This is the same single-storey rear extension priced in each region.
| Region | Building work | Budget to plan for, with fees and 15% contingency |
|---|---|---|
| UK average (outside London) | £63,500 to £78,000 | £77,500 to £98,500 |
| London | £86,000 to £105,000 | £103,000 to £131,000 |
| South East | £73,000 to £89,500 | £88,500 to £113,000 |
| East of England | £68,000 to £83,500 | £82,500 to £105,000 |
| South West | £66,000 to £81,000 | £80,500 to £102,000 |
| West Midlands | £61,500 to £75,500 | £75,500 to £96,000 |
| East Midlands | £60,500 to £74,000 | £74,000 to £94,000 |
| Scotland | £60,500 to £74,000 | £74,000 to £93,500 |
| North West | £59,000 to £72,500 | £72,000 to £91,500 |
| Yorkshire and the Humber | £58,500 to £72,000 | £71,500 to £90,500 |
| Wales | £57,000 to £70,000 | £70,000 to £89,000 |
| North East | £56,000 to £68,500 | £68,500 to £87,000 |
| Northern Ireland | £52,000 to £64,000 | £63,500 to £81,000 |
Which region is my town in? Brighton, Oxford and Southampton are in the South East; Cambridge and Norwich in the East of England; Bristol, Bath and Exeter in the South West; Birmingham and Coventry in the West Midlands; Nottingham and Leicester in the East Midlands; Glasgow and Edinburgh in Scotland; Manchester and Liverpool in the North West; Leeds, Sheffield and Hull in Yorkshire and the Humber; Cardiff and Swansea in Wales; Newcastle and Sunderland in the North East; and Belfast in Northern Ireland. Somewhere else? Type your postcode into the calculator above and it says which region’s prices it uses.
Download every project, finish and region as the UK Renovation Cost Index 2026 Q3 (CSV), free to use with a link back to Estiquote.
Cost guides for every project
- House extension costs
- Loft conversion costs
- New kitchen costs
- Bathroom costs
- Garage conversion costs
- Whole-house renovation costs
- New build house costs
- House rewire costs
- New consumer unit (fuse board) costs
- EV charger installation costs
- Electrical safety report (EICR) costs
- New roof costs
- Knock-through with steel beam costs
- New boiler costs
- Unvented cylinder replacement costs
- Air source heat pump costs
- Replacement windows costs
How accurate is it?
The ranges come from published 2026 UK cost guides and our own council fee research, adjusted for your region and checked every quarter. They are budget ranges for planning and for challenging quotes. They are not a builder's price: site conditions, access and specification can move a real quote outside the range. Read the method.