What a House Renovation Costs in Prime London
Published 19 August 2026. Figures are current published 2026 market ranges; we review this page every six months. Last reviewed 19 August 2026.
Most builders in this part of London will not put a number on a website. That makes it hard to plan, and it means the first honest conversation about money happens after you have already spent a month getting quotes.
Here is what the published 2026 figures say, where they come from, and what actually moves the number on a Kensington or Chelsea property. Everything below excludes VAT, professional fees and local authority charges unless stated.
The 2026 ranges at a glance
| Project type | Typical 2026 range | Includes | Excludes |
|---|---|---|---|
| Full house renovation | £800–£3,500 per m² (high specification from about £3,000, luxury above £4,000) | Labour and materials | VAT, professional fees, council charges |
| Rear or side-return extension | £1,800–£2,800 per m² | Shell and basic finish, VAT included in this source | Kitchen, joinery, glazing upgrades |
| Loft conversion (London) | Rear dormer £50,000–£90,000; mansard £80,000–£120,000 | Fitted conversion | Party wall fees, finish upgrades |
| Basement (~40 m², excavated) | £100,000–£160,000 | Excavation, underpinning | High-end fit-out, borough policy constraints |
All figures are published 2026 market ranges; the sources are named beside each section below. Everything excludes VAT, professional fees and local authority charges unless stated.
Full house renovation costs in London (2026)
Published London guides for 2026 put a full renovation anywhere from roughly £900 per square metre for cosmetic work to beyond £4,000 per square metre at the top of the market, with the spread explained almost entirely by specification and by what is found behind the walls. High specification work in prime west London starts around £3,000 per square metre, and luxury work with bespoke joinery, full replumbing and rewiring, and complex services runs above £4,000.
For a whole property, take a typical three or four bedroom London terrace at 120 to 180 square metres: full renovation lands somewhere between £150,000 and £500,000 depending on specification. A cosmetic refresh, meaning decoration, flooring and one or two rooms replaced, sits far lower.
Sources: 2026 London renovation cost guides published by Bradley Van Der Straeten Architects and NU Projects.
House extension costs
The Homeowners Alliance puts a ground floor rear extension at £1,800 to £2,800 per square metre (that figure includes VAT, unlike the rest of this page). A typical side return of 15 to 20 square metres therefore falls between about £27,000 and £56,000 including VAT for the shell and basic finish, before kitchen, joinery and glazing. In a conservation area, expect the design and consent stage to add both time and cost before any building starts.
Source: Homeowners Alliance, house extension costs.
Loft conversion costs
The 2026 UK midpoint for a rear dormer loft conversion is around £55,000, with a typical range of £40,000 to £75,000. London runs 25 to 40 per cent above the Midlands and the north, so a rear dormer in the capital is more commonly £50,000 to £90,000. Mansard conversions, which is what most prime London terraces need, routinely exceed £80,000 and reach £120,000 inside inner London. A rooflight conversion, where the roof structure allows one, is the cheapest route at £20,000 to £40,000.
Source: Checkatrade loft conversion cost guide, 2026.
Basement costs
Published 2026 guides put a basement of around 40 square metres requiring excavation and underpinning at £100,000 to £160,000. In Kensington and Chelsea the borough’s basement policy limits most schemes to a single storey under no more than half the garden, which caps what is possible before cost even enters the conversation. Check the constraint before budgeting the space.
Source: houseUP 2026 conversion cost guides.
The costs people forget
Checkatrade’s 2026 guide puts party wall surveyor fees at £700 to £2,000 for each neighbouring property, and in a terrace you may have two. The same guide finds finishing items, meaning flooring, decoration, bathroom fit-out and specialist surveys, add 10 to 15 per cent on top of a quoted build. Scaffolding, parking bay suspensions and skip permits are real money in central London and belong in the budget from the start rather than as variations later.
What moves the number most
Condition. Behind the plaster of a Victorian terrace you find sound brick or you find a rebuild. A proper survey before quoting narrows this, but some of it cannot be known until opening up, which is why a stated contingency belongs in the quotation rather than in a conversation at the end.
Finish. The same extension shell carries a fitted kitchen at £15,000 or one at £60,000. Most of the difference between two quotes for the same house is finish level, not builder margin.
Planning. Around 70 per cent of Kensington and Chelsea is conservation area and the borough has more than 3,800 listed buildings. Westminster has 56 conservation areas. Listed building consent adds design time and sometimes specialist materials. None of that is a reason not to build. All of it belongs in the budget on day one.
Questions we get asked about cost
Why are prime London renovation quotes so different from each other?
Because they are rarely quoting the same job. Check what each one includes: VAT, contingency, professional fees, making good, decoration. A low headline number with the essentials missing is the most expensive quote on the table.
Is a per square metre figure reliable?
It is a planning tool, not a price. It works for early budgeting and it breaks down on small areas, complex structures and heavily serviced rooms. Kitchens, bathrooms and plant rooms cost several times the average square metre in the same house.
Does a conservation area make renovation more expensive?
Usually yes, in design time, materials and sometimes in method. Sash windows, lime mortar and slate have to match, and consent conditions can specify them.
When can a builder give a fixed price?
After a survey and a defined specification. Anyone who fixes a price on a prime London period property without seeing it is either guessing or pricing the variations they expect to charge later.
A worked example: 150 square metre period property
Take a full renovation of a 150 square metre Victorian terrace at a mid specification of £1,800 to £2,200 per square metre from the published ranges above. The build cost comes to £270,000 to £330,000. On top of that, stated separately rather than hidden: VAT at 20 per cent adds £54,000 to £66,000; professional fees (architect, structural engineer, party wall surveyors) at 10 to 15 per cent add roughly £27,000 to £50,000; and a sensible 10 per cent contingency holds £27,000 to £33,000 against what the walls hide. The realistic all-in planning figure is therefore £378,000 to £479,000, not the £270,000 headline. This is an illustration built from the published ranges, not a quotation; the four-storey Victorian renovation in Highbury shows what a project of this type looks like in practice.
How these figures were put together
The ranges on this page come from cost guides published in 2026 by London construction firms, architects and consumer bodies, including the Homeowners Alliance and Checkatrade, cross-checked against each other and against what specialist firms publish for prime central London. Where sources disagree, the range shown covers the credible spread rather than the single most quotable number. Figures are checked every six months and the review date below changes only when that check has actually been done.
Talk to us about your project
We renovate houses across Kensington, Chelsea, Westminster, Camden, Paddington and Notting Hill, and we have been doing it since 2014. If you want the figures above turned into a number for your property, send us the address and what you want to do with it, or call +44 (0)20 7126 8150.
