House Extensions & Loft Conversions across Central London

LCCL Construction is a design and build company based in Finchley N3, working across Central London for over 20 years. One team, one contract: architects, structural engineers, project managers and builders coordinated by LCCL take your project from first sketch to handover.

Central London work is mostly period property: Georgian and Victorian terraces in Islington and Camden, stucco villas and mansion flats in Kensington & Chelsea and Notting Hill, mews houses in Westminster. Space is tight, access is tighter, and the value of every square metre is high — which is why basements, loft conversions and full renovations dominate here rather than large footprints.

What it costs across Central London

Central London — typically +20–25% on base prices. 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: £32,500–£52,500
• Rear dormer loft: £56,500–£84,000
• L-shaped dormer: £59,000–£102,500
• Hip to gable: £60,000–£119,000
• Mansard: £77,000–£155,000
• Rear extension: £42,000–£94,000
• Side return: £42,000–£97,500
• Wraparound: £72,000–£160,000
• Double storey: £90,000–£206,000

Kitchen fit-out on top of the structure: +£15,000–£75,000. Basements: cellar refit £45k–£95k, lowering £95k–£180k, new dig £180k–£300k+. New build: £2,200–£4,500 per sqm.

A recent LCCL project near Central London

Weech Road, Hampstead NW6 — penthouse duplex loft conversion

A top-floor flat turned into a penthouse duplex: the kitchen and living space moved up into the new loft, two new bathrooms, an extra bedroom and views across to the Shard, the London Eye and Parliament. LABC Building Excellence Awards 2026 London Regional Winner — Best Conversion or Alteration to an Existing Home.

See the project

Planning across Central London

Expect conservation areas almost everywhere, Article 4 directions removing some permitted-development rights, and listed buildings in the older squares. Kensington & Chelsea and Westminster scrutinise basements closely (construction method statements, party wall awards, traffic management). Our architects prepare heritage statements and pre-application submissions as standard for these boroughs.

Borough by borough

Kensington & Chelsea protects nearly three quarters of the borough in 38 conservation areas, has more than 200 street-specific Article 4 directions and requires full planning permission for every basement (Article 4 in force 28 April 2016; policy CD11 limits basements to one storey, 50% of the garden and 1 m of soil cover). Westminster has 56 conservation areas, a city-wide basement Article 4 (31 July 2016) and City Plan policy 45 on similar lines. Camden adds a borough-wide basement Article 4 (1 June 2017) with audited Basement Impact Assessments and 2010 Article 4 directions across Hampstead and Belsize. Islington has Article 4 directions in 40 of its 42 conservation areas and conservation guidelines that rule out most visible roof extensions. Pre-application advice ranges from £456 (Westminster) to £559 (RBKC) for a written householder response. See our Kensington & Chelsea, Notting Hill, St John’s Wood, Camden and Islington pages.

Anderson's advice: start the party wall process early

Most clients underestimate the party wall timeline — it can add three months to a semi-detached or terraced project. We raise it at the first meeting so notices go out while the design is still being finalised, not after.

What our clients say

“Super professional and on the ball at all times. All his teams are excellent and hard working. 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 Warranty available to purchase.

Areas we cover

Dedicated pages for the areas we work in most:

• Islington
• Camden
• Kensington & Chelsea
• Notting Hill
• St John's Wood

We also work across Westminster, Marylebone, Maida Vale, Bayswater, Holland Park, Pimlico, Bloomsbury and Clerkenwell — the same team, the same contract and the same price bands 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.