London is where the headline quote and the true cost diverge most — restricted access, party walls, conservation areas. Here's what a modular extension really costs across the capital, and why the fixed price matters most here.
The short answer: Vita Modular's modular house extensions in London start from £34,000 inc. VAT, priced at around £3,000/m² (ground floor) and £2,750/m² (first floor) for a complete, weathertight, decorated shell. A 15m² side-return from £45,000; a 21m² wraparound from £63,000. No cranes — so tight terraced and side-return sites are viable — with party-wall and planning support in every borough. All figures are Vita Modular prices, inclusive of VAT.
London is where the true cost of an extension diverges most sharply from the headline quote. Restricted access, party-wall agreements with close neighbours, conservation areas, and the sheer disruption of a months-long wet-trade build on a terraced street all add cost, time and risk that a per-m² figure rarely captures.
A Vita Modular extension is priced differently: one fixed, all-inclusive shell rate, inclusive of VAT, for a complete weathertight and decorated build — the structural steel frame, external walls, silicone render, roof, installation, electrics and lighting, flooring, painted walls and ceilings, and glazing up to 3m. Ground-floor and single-storey work is around £3,000/m²; a first floor added above is £2,750/m² and includes the pitched roof and scaffolding.
| Extension | Size | From (inc. VAT) | Typical London use |
|---|---|---|---|
| Side-return / single-storey | 15m² | £45,000 | Victorian terrace kitchen widening |
| Single-storey rear | 18m² | £54,000 | Open-plan kitchen-diner |
| Wraparound (rear + side) | 21m² | £63,000 | L-shape transforming the ground floor |
| Single-storey rear | 28m² | £95,420 | Large family living space (real project) |
| Two-storey rear | 40m² | £117,750 | Bedroom & en-suite above a new kitchen |
| Large bespoke | 60m²+ | from £197,000 | Whole-rear reconfiguration (real project) |
Prices inclusive of VAT for the complete shell. Kitchens, bathrooms, demolition, ground preparation, structural openings, professional fees and landscaping are quoted separately at fixed prices — never a mid-build surprise. See the full national pricing guide →
The sizes above are common examples, not a fixed menu: every Vita Modular extension is bespoke — any size and any shape, manufactured to suit your property. Pricing is pro rata per square metre on the same shell rate (£3,000/m² ground floor, £2,750/m² first floor), so you can scale the figures above to your own dimensions and get a consistent, predictable price whatever the footprint.
If you own a Victorian or Edwardian terrace, the side return is almost certainly the best-value space you can add — the narrow, usually wasted strip alongside your kitchen. It's the most requested extension in London, and Vita's off-site method is ideally suited to it: because the panels are hand-assembled with no crane and no heavy plant, the tight alley that rules out crane-lifted modular is no obstacle. Site access doesn't affect the price, either — there's no access surcharge for a constrained terraced plot.
London extensions almost always involve the Party Wall etc. Act 1996, because you're building right up to a shared boundary with close neighbours. Vita provides planning and party-wall support across every London borough. Where planning permission is needed, we build exactly to your pre-approved drawings, or we can produce and manage the application for you — often more cost-effective than instructing an architect separately. Either way, our designers complete the technical building-control drawings the build is made from.
Our system also has a practical structural advantage on constrained London plots: because the panels are precision-made off-site and hand-assembled, we can efficiently build tight up to party boundaries — maximising every centimetre of a narrow terraced or side-return site — where a conventional wet-trade build needs working room for scaffolding, cavity access and bricklaying that a shared boundary rarely allows.
Much of London sits within conservation areas or comprises period terraces with strict material requirements. A common assumption is that a modular system can't meet them — it can. Vita matches effectively any external finish a conservation area or planning condition requires, from brick slip and timber to render, with the steel frame and panels sitting behind a compliant façade. And complex, hand-laid brickwork detailing is well within scope.
On headline £/m², a local builder's quote can look competitive — but a traditional London builder typically quotes £2,500–£3,500/m² for a basic shell, rising to £4,000–£4,500+/m² once you add VAT, glazing, electrics, flooring and the inevitable variations. Vita's fixed, all-inclusive price covers the lot from the start. And London builds are especially prone to overrun once variation orders, access issues and party-wall delays compound. A Vita extension is a single fixed price under one JCT contract, with a single clear source of responsibility from design to handover, finished far faster than a comparable traditional build. Full head-to-head comparison →
We price-test ourselves regularly against other London extension providers, including Simply Extend and Plusrooms. On average, we come out at least 15% more cost-effective than them on a like-for-like basis. A large part of the difference is how the work is delivered: those providers typically subcontract the build out to other local builders, whereas Vita uses our own directly employed, skilled installers on every project. That keeps quality consistent, accountability clear and cost down — you deal with one team, under one contract, from first quote to handover. And we back our pricing with a Price Beat Guarantee: find a genuine like-for-like quote for less and we'll beat it.
In a city where a builder's overrun can run into tens of thousands and a party-wall dispute can stall a site for weeks, price and timeline certainty are worth more than anywhere else in the country. Vita's fixed shell price, written completion date and single point of responsibility are designed precisely for that context — you know the number, you know the date, and one party is accountable for the result.
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