Building Costs in London
London building costs are the highest in the UK, driven by premium trade labour rates, ULEZ and logistics costs, and longer supply chains for specialist materials and subcontractors.
Build costs in London (2026)
| Project type | Typical cost (2026) |
|---|---|
| New build (basic) | £2,200–£2,700/m² |
| New build (mid spec) | £2,700–£3,400/m² |
| New build (high spec) | £3,400–£4,500/m² |
| Rear extension | £1,900–£4,200/m² |
| Loft conversion | £60,000–£130,000 |
| Full refurbishment | £700–£2,500/m² |
Key factors affecting cost in London
Market context
London accounts for approximately 25% of all UK construction output by value. The market is highly active, with strong demand across residential extensions, loft conversions, and full refurbishments particularly in inner and south-east London.
High demand for loft conversions (particularly dormers and mansards) across inner London. Strong extension activity in south-east and east London boroughs.
Planning and Building Regulations
32 London Boroughs + City of London Corporation
Planning rules vary by borough. Inner London boroughs (Westminster, Kensington & Chelsea, Camden, Islington) have the most restrictive conservation area policies. Check borough-specific guidance before assuming permitted development applies.
Building Control applications can be made to your borough council or an Approved Inspector. Most London loft conversions require fire safety upgrades to the escape route.
Costs in nearby areas
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