House Extensions & Loft Conversions across East London

LCCL Construction is a design and build company based in Finchley N3, working across East 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.

East London projects are mainly Victorian terraces in Hackney, Walthamstow and Leyton — rear and side-return kitchen extensions and rear dormers — with warehouse conversions and mansion flats closer to the City. Plots are narrow, so getting light in (rooflights, glazed rear elevations) matters as much as floor area.

What it costs across East 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).

A recent LCCL project near East 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 East London

Hackney has wide conservation-area coverage and is careful about roof extensions on terraces; Waltham Forest and Newham are generally straightforward for permitted development. Party wall agreements on both sides are standard on terraces.

Borough by borough

Hackney approved a new Residential Extensions and Alterations SPD in December 2025 (in effect from January 2026) with clear numbers — 3 m, 3.5 m and 4 m single-storey rear depths by house type, rear dormers 0.5 m below the ridge, a codified 45-degree daylight test — and generally refuses roof extensions on unaltered conservation-area rooflines. Waltham Forest adopted its Residential Alterations and Retrofit SPD in June 2026: first-floor rear extensions no more than 2 m on a terrace or semi and 3 m on a detached house, single-storey extensions over 3 m long kept to 2.4 m at the boundary, dormers set in 0.25 m from the ridge and eaves, and codified 25-degree and 45-degree tests; ten of its fifteen conservation areas carry Article 4 directions (Walthamstow Village’s dates from 1977). Tower Hamlets has no extensions SPD and no householder Article 4 directions — its 58 conservation areas are managed through their appraisals and Local Plan policies S.DH1, D.DH3 and D.DH8, with terrace rooflines protected and mansards only to the prescribed design sheets; its written pre-application advice is the cheapest in London at £119. Newham decides under its 2018 Altering and Extending Your Home SPD, which is qualitative outside the Woodgrange Estate (ground-floor rear extensions only, 3 m from the main house, no dormers), with Article 4 directions in Woodgrange, Durham Road and Romford Road and a borough-wide small-HMO direction since 31 July 2013. All four run their own building control. See our Stoke Newington page for the Hackney detail.

Anderson's advice: budget for the steelwork, not just the kitchen

Clients budget for kitchen units but forget the structural steelwork when opening up ground-floor walls. On a Victorian terrace that is typically £4,800 – £19,200 inc. VAT (£4,000 – £16,000 + VAT) for the load-bearing opening, depending on its width — we price it on every proposal so there is no surprise.

What our clients say

“LCCL Construction were professional from start to finish. The team were trustworthy, reliable and delivered work to the highest standard.”

— KashImaging, Trustpilot

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:

• Stoke Newington

We also work across Hackney, Dalston, Clapton, Walthamstow, Leyton, Leytonstone, Wanstead, Stratford, Bow, Bethnal Green and Chingford — 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.