House Extensions & Loft Conversions across West London

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

West London for us means Ealing, Chiswick and Acton: Edwardian and inter-war family houses with generous rear gardens, so kitchen extensions with rooflights and rear dormers are the common projects. Chiswick's Bedford Park and Ealing's conservation areas need a lighter touch on the street elevation but rarely block a well-designed rear extension.

What it costs across West London

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 West London

Second Avenue, Queen's Park W10 — side return extension

A side return extension to a Victorian terrace in Queen's Park: the narrow side passage brought inside to make a full-width open-plan kitchen.

See the project

Also nearby: Chipstead Street, Fulham SW6 (basement, loft conversion, rear extension, renovation, 2024) · Victoria Road, Maida Vale W9 (kitchen extension, 2025).

Planning across West London

Ealing and Hounslow use standard householder and permitted-development routes with prior approval for larger rear extensions; conservation areas (Bedford Park, Ealing Common, Hanwell) remove some permitted-development rights. Chiswick terraces usually need two party wall awards.

Permitted development in West London: what goes ahead without a planning application

Usually permitted development outside the garden estates. Ealing’s Article 4 directions cover the Brentham Garden Estate, Bedford Park, Hanger Hill and a few others; Hounslow’s cover Bedford Park and Gunnersbury Park; Hammersmith & Fulham’s borough-wide direction covers basements only. 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

Borough by borough

Ealing decides under its 2013 Development Management DPD and 2004 extensions guidance (3 m single-storey rear depth, first-floor side extensions set back 1 m, hip-to-gable normally refused), with 30 conservation areas and Article 4 directions in Brentham, Bedford Park and the Hanger Hill estates. Hounslow applies its December 2017 Residential Extension Guidelines (3.05 m, 3.65 m and 4.25 m rear depths by house type, dormers 0.3 m below the ridge) with Article 4 directions only in Bedford Park and Gunnersbury Park. Hammersmith & Fulham guides rear extensions to 3.5 m, applies a 45-degree test and requires planning permission for every basement. See our Ealing, Chiswick and Fulham pages.

Anderson's advice: put the rooflights over the island

Rooflights over kitchen islands transform natural light more than any other single design decision. We position them on the plan before the kitchen layout is fixed, not after.

What our clients say

“Alex is super professional and on the ball at all times. He always thinks ahead and won't let you down. All his teams, from bricklayers, carpentry to electrics, roofing, tiling, painting, flooring and plumbing are excellent and hard working. They are all friendly yet professional. They are conscientious and want the job to be well done.”

— Ludovic, Reviews.io

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.

Areas we cover

Dedicated pages for the areas we work in most:

• Ealing
• Chiswick

We also work across Acton, Hanwell, Hammersmith, Shepherd's Bush, Brentford and Northfields — the same team, the same contract and the same prices apply, and we survey every project in person before quoting.

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.