House Extensions & Loft Conversions in Clapham

LCCL Construction is a design and build company based in Finchley N3, working in Clapham. One team, one contract: architects, structural engineers, project managers and builders coordinated by LCCL take your project from first sketch to handover.

Clapham, Battersea and Balham terraces are the classic South West London extension houses: side-return kitchen extensions with rooflights, rear dormers and L-shaped dormer lofts. Abbeville Village and Clapham Old Town add larger period houses for full renovations.

What it costs in Clapham

The final figure depends on postcode, access and site conditions — the instant estimate applies your area. Guide ranges for 2026, design and build inclusive (architecture, structural engineering, planning or LDC, construction, project management and building control). Every project is surveyed and priced individually.

• Velux loft: £32,400 – £50,400 inc. VAT (£27,000 – £42,000 + VAT)
• Rear dormer loft: £56,400 – £80,400 inc. VAT (£47,000 – £67,000 + VAT)
• L-shaped dormer: £58,800 – £98,400 inc. VAT (£49,000 – £82,000 + VAT)
• Hip to gable: £60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT)
• Mansard: £76,800 – £148,800 inc. VAT (£64,000 – £124,000 + VAT)
• Rear extension: £42,000 – £90,000 inc. VAT (£35,000 – £75,000 + VAT)
• Side return: £42,000 – £93,600 inc. VAT (£35,000 – £78,000 + VAT)
• Wraparound: £72,000 – £153,600 inc. VAT (£60,000 – £128,000 + VAT)
• Double storey: £90,000 – £198,000 inc. VAT (£75,000 – £165,000 + VAT)

Kitchen on top of the structure, supplied and fitted: +£9,000 – £87,360 inc. VAT (£7,500 – £72,800 + VAT) depending on size and specification. Basements: cellar refit £54,000 – £114,000 inc. VAT (£45,000 – £95,000 + VAT), lowering £114,000 – £216,000 inc. VAT (£95,000 – £180,000 + VAT), new dig £216,000 – £360,000 inc. VAT (£180,000 – £300,000 + VAT)+. New build: £2,200 – £4,500 per sqm (zero-rated for VAT).

Recent LCCL projects near Clapham

Glendarvon Street, Putney SW15 — rear extension

A rear extension to a Victorian terrace in Putney: an open-plan kitchen-diner with skylights and bifold doors onto a landscaped garden, plus a new WC and pantry tucked into the old footprint.

See the project

Also nearby: Westleigh Avenue, Putney SW15 (dormer loft, 2024) · Chipstead Street, Fulham SW6 (basement, loft conversion, rear extension, renovation, 2024).

Planning in Clapham

Lambeth and Wandsworth share the area; Wandsworth engages well at pre-application, Lambeth runs standard routes. Clapham Common, Abbeville and Old Town conservation areas need planning permission for roof changes.

Permitted development in Clapham: what goes ahead without a planning application

Usually permitted development. Lambeth has no Article 4 direction on the Clapham, Abbeville Road or Brixton conservation areas (Lansdowne Gardens, Albert Square, Stockwell Park and Hyde Farm carry one), and Wandsworth’s directions are street-specific (Commondale, Westover Road, Wandsworth Common West Side, the Heaver Estate). On the ordinary streets, lofts and single-storey rear extensions go ahead without a planning application. Flats and maisonettes have no permitted development rights, whatever the street, and inside any conservation area a dormer or roof enlargement needs a planning application even where a single-storey rear extension within the limits does not.

On a house outside those streets, a rear dormer loft (40 m³ on a terrace, 50 m³ on a semi or detached house), a hip-to-gable, a single-storey rear extension of 3 m (4 m on a detached house) and a side-return infill are permitted development, and we apply for a Lawful Development Certificate on every one so the position is confirmed in writing. See our fixed-price permitted development projects — from £32,400 inc. VAT (£27,000 + VAT) for a Velux loft and £42,000 inc. VAT (£35,000 + VAT) for a 3 m rear extension, design and build inclusive, postcode dependent. Not sure whether your project needs a planning application?

Planning check

Conservation areas and Article 4 directions in Clapham

Clapham is split between Lambeth and Wandsworth along the Common. On the Lambeth side, the Clapham conservation area (CA1, designated 20 June 1968) is centred on the Common and the 18th- and 19th-century core, Abbeville Road (CA30) covers the tightly packed 1880s–90s yellow-stock terraces with decorative brickwork, and Clapham Park and Northbourne Road (CA17) lies to the south-east; none of the three has an Article 4 direction. On the Wandsworth side, Clapham Common (1969, appraisal 2007) covers the stock- and gault-brick terraces towards Clapham Junction, with Nightingale Lane and Clapham Junction conservation areas beyond. Front-facing replacement windows therefore remain permitted development across Clapham, but roof, side and two-storey rear extensions inside any of these areas need planning permission.

Lambeth’s rules (Clapham, Abbeville Road, Clapham Park)

Lambeth’s Design Guide SPD (adopted 8 August 2023) implements Local Plan policy Q11: extensions subordinate (para 4.45), closet-return upper floors ending half a storey below the eaves (4.49), infills single storey (4.55), side extensions at least 1 m from the boundary above ground (4.68), dormers on rear slopes only with a cill about 1 m up and head at least 2.1 m (4.90–4.91), rear mansards at 70 degrees to 2.3 m, not on hipped roofs and generally not in conservation areas (4.101–4.102). Basements under policy Q27 are one floor below ground (5.28), keep at least 70% of the rear garden free at its original level (5.30), have a floor-to-ceiling height of no more than 3 m (5.33) and need a Basement Impact Assessment screening by chartered professionals. Daylight is judged against BRE 209 (2022). Written householder pre-application advice is £491 (2026/27), £820.46 with a meeting or £984.88 in a conservation area; Lambeth Building Control is our own and an LABC partner.

Wandsworth’s rules (Clapham Common west side, Clapham Junction)

Wandsworth’s Local Plan (19 July 2023) policies LP5 and LP6 and the Housing SPD (2016) keep extensions subordinate and two-storey extensions away from the neighbour’s boundary, with daylight judged under the BRE guide; basements keep half the front and rear garden, 1 m of soil and a single level. Written pre-application advice is £146 (2026/27) with a free duty-planner email service, and building control is the shared Richmond and Wandsworth service.

Fees and timescales

Either council charges £548 for a householder application (from April 2026, plus the Planning Portal charge) and has eight weeks to decide it. Party wall notices run alongside planning: two months’ notice for works to a shared wall, one month for excavations within 3 m or 6 m of a neighbour’s foundations. We book every building control inspection from foundations to completion with whichever council the house falls in.

Anderson's advice: use pre-application advice where the council engages

Wandsworth planning is much more helpful on pre-application than Islington in our experience. Where a council engages, a pre-app saves weeks; where it does not, a well-argued application with precedent cases works better.

What our clients say

“We have used Lccl in the past for our rear house extension and have come back to instruct Lccl for our loft conversion too to our house in North London. As before we are very happy with the services from Lccl and we highly recommend their design and construction services for both home extension or loft conversion including both design and build services.”

— Mia M, Google Reviews

As LABC Building Excellence Award winners in 2024 (Best Residential Extension in London) and 2026 (Best Conversion or Alteration to an Existing Home, Weech Road NW6), every project is delivered by one team of architects, structural engineers, project managers and builders. Workmanship is guaranteed for 12 months from practical completion, with a 10-year LABC structural warranty.

Nearby areas

Clapham is part of our South West London guide. Nearby areas: Fulham, Richmond, Putney & Wandsworth, Wimbledon.

To book a free consultation call LCCL Construction on 020 8037 7332 or get an instant estimate online. Get an instant estimate or book a free consultation.

One team, one contract, one point of contact — from first sketch to handover.