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Single and double storey rear and side extensions across North West London. 1930s semis in Golders Green, Hendon, and HA postcodes have excellent Permitted Development scope.
Find a builder →Velux, dormer, hip-to-gable, and mansard loft conversions. NW London's mix of period terraces and 1930s semis suits a variety of conversion types.
Find a builder →Full house refurbishments and internal remodelling. Premium specifications in NW3 and NW8; value-focused refurbishments in Kilburn, Willesden, and Wembley.
Find a builder →Office refurbishments and shopfits across North West London including Wembley commercial zone, Edgware Road, and Brent Cross.
Find a builder →RSJ steel beam installations, load-bearing wall removals, and underpinning. Open-plan kitchen-diners are a popular structural project across NW London family homes.
Find a builder →Garden studios, new build projects, and garage conversions. Larger NW London plots in Hampstead Garden Suburb and Mill Hill suited to outbuildings and new builds.
Find a builder →| Job | Low estimate | High estimate |
|---|---|---|
| Single-storey extension | £25,000 | £50,000 |
| Double-storey extension | £45,000 | £90,000 |
| Loft conversion (Velux) | £20,000 | £35,000 |
| Loft conversion (dormer) | £35,000 | £65,000 |
| Full refurbishment (3-bed) | £40,000 | £100,000 |
| Kitchen extension | £30,000 | £60,000 |
| Garage conversion | £12,000 | £25,000 |
| Garden room / studio | £15,000 | £40,000 |
| Basement conversion | £40,000 | £80,000 |
| Party wall agreement | £700 | £2,000 |
| RSJ beam installation | £1,500 | £4,000 |
| New build (per m²) | £2,000 | £4,000 |
Prices are estimates for North West London 2026. Actual costs vary by job complexity, specification, and location. Always get multiple quotes.
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North West London spans a wide range of property types and price points. NW3 (Hampstead) and NW8 (St John's Wood) sit at the premium end — large Victorian and Edwardian detached and semi-detached homes where extensions and basement conversions regularly cost in excess of £100,000 due to high specification requirements, structural complexity, and the need for conservation area compliance in Hampstead. Hampstead Garden Suburb in NW11 is another high-value area with strict planning controls governing the appearance of all external building work.
Further out, Golders Green, Hendon, and Brent are dominated by 1930s semis — a property type particularly well suited to Permitted Development extensions. These homes typically have side access, a garage, or rear garden space that allows a double-storey side and rear wraparound extension within Permitted Development limits, adding significant living space and value. The HA postcode areas (Harrow) similarly have a large stock of 1930s and 1950s semis with good extension potential.
Kilburn and Willesden offer more affordable entry points where Victorian and Edwardian terraces are popular with first-time buyers who then invest in extending and upgrading. When hiring a builder in North West London, confirm they hold public liability insurance, check reviews and references for recent local projects, and ensure your contract specifies materials, timescales, and payment milestones clearly.
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