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Single and double storey rear and side extensions across Clapham SW4, SW9, and SW11. Open-plan rear kitchen extensions are by far the most popular project in Clapham's Victorian terraces.
Find a builder →Velux, dormer, hip-to-gable, and mansard loft conversions. Clapham terraces regularly benefit from a dormer loft conversion adding a master bedroom suite with en suite bathroom.
Find a builder →Full house refurbishments and internal remodelling. Clapham's strong resale market rewards quality refurbishments — buyers in SW4 expect high-specification kitchens and bathrooms.
Find a builder →Office refurbishments and shopfits along Clapham High Street, Clapham Manor Street, and the surrounding commercial district.
Find a builder →RSJ steel beam installations, load-bearing wall removals, and underpinning. Ground-floor open-plan remodelling is the most requested structural project in Clapham.
Find a builder →Garden studios and outbuildings for larger Clapham properties. Garage conversions to additional living space also popular across SW4 and SW11.
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 Clapham 2026. Actual costs vary by job complexity, specification, and location. Always get multiple quotes.
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Clapham — covering SW4, SW9, and parts of SW11 — is one of south London's most popular areas for young professionals and families. The housing stock is dominated by Victorian terraces with two to four bedrooms, long rear gardens, and relatively standard footprints. The combination of good property values and significant demand for family-sized homes makes Clapham one of London's most active markets for rear extensions. Creating an open-plan kitchen-dining-living space by extending into the rear garden is by far the most requested project type, typically adding one large room on the ground floor and opening onto the garden with bi-fold or sliding glass doors.
Party wall agreements are required in virtually all Clapham extension projects. The party wall boundary runs along the shared walls with neighbouring terraced properties, and any extension that touches or works within three metres of a neighbour's structure requires a formal party wall notice. Your builder should be able to advise you on this process and recommend a surveyor if needed. Failure to serve party wall notices before starting work can result in disputes and delays, so it's important to address this early in the planning process.
Loft conversions are also extremely popular in Clapham. Most Victorian terraces in SW4 have a rear back-addition return that limits the usable roof space, but a well-designed dormer loft conversion can still deliver a master bedroom, en suite bathroom, and storage — adding significant value in Clapham's competitive resale market. When hiring a builder, check references from recent local projects, confirm insurance, and use a payment schedule tied to clear milestones.
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