House Extensions & Loft Conversions in Hendon

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

Hendon and Colindale mix 1930s semis with newer developments. Hip-to-gable lofts and rear dormers on the semis, kitchen extensions and full renovations on the older stock around Hendon Central and the Burroughs.

What it costs in Hendon

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 Hendon

Guardhouse Way, Millbrook Park, Mill Hill NW7 — kitchen extension

A large modern kitchen and dining space for a family home, with a separate utility room so the kitchen stays quieter and gains cupboard space.

See the project

Planning in Hendon

Barnet council; the Burroughs and Hendon Church End conservation areas need planning permission for roof extensions, everywhere else permitted development normally applies.

Conservation areas and Article 4 directions in Hendon

Two conservation areas cover the old village core. Hendon The Burroughs (Article 4 since 21 July 1987) takes in the civic buildings and houses around The Burroughs and Church Road, where front-facing alterations, windows, porches and roof changes need planning permission. Hendon Church End around St Mary's church is a conservation area without an Article 4 direction, so permitted development still applies but the council will scrutinise design and materials. The wider NW4 and NW9 streets — Brent Street, Hendon Central, West Hendon and the interwar semis towards Colindale — are outside any conservation area and most lofts, rear and side extensions go through on a Lawful Development Certificate. Since 29 May 2016 a borough-wide Article 4 direction has also required planning permission to convert a house into a small HMO.

Extension size rules Barnet applies (SPD adopted 15 June 2026)

Barnet adopted its Sustainable Design and Development Guidance SPD on 15 June 2026, replacing the 2016 Residential Design Guidance, and Part 4 of it sets the numbers officers use alongside Local Plan policy CDH05. Single-storey rear extensions can run the full width of the house to a maximum depth of 3 m on a terrace, 3.5 m on a semi and 4 m on a detached house (paras 4.37–4.39), no more than half the garden length (4.40), up to 4 m high with a pitched roof but with eaves no higher than 3 m (4.41–4.42). A larger home extension approved under prior approval (6 m on a semi or terrace, 8 m detached) is accepted as a fallback position (4.45). Two-storey rear extensions are limited to half the width of the house and 3 m deep, kept 2 m from an attached neighbour’s boundary or 1 m from a detached one, with a pitched roof matching the original (4.53–4.57). Side extensions should be no more than half the original width; at first floor they need a 1 m gap to the boundary, a 0.5 m set-back from the front wall and a ridge 0.5 m below the main roof (4.69–4.74). Rear dormers should sit at least 0.5 m in from the eaves, ridge and edges of the roof (4.87); L-shaped dormers over an outrigger are limited to half its depth (4.95); front dormers are generally not supported (4.85), while a hip-to-gable that re-balances a pair of semis is (4.84). Basements are single storey with 2.5 m head height, project no further than the rear-extension limits above, take up no more than half the garden length and have front lightwells of no more than 1 m (4.103–4.121). In the Green Belt the original house should not grow by more than 25% by volume (4.163).

Light to neighbours

The SPD does not set a numerical daylight test; it asks officers to weigh loss of light to main windows of neighbours’ habitable rooms (para 4.7) and to reduce depth or height, or set off the boundary, where levels or building lines differ (4.8). In practice we design every Barnet extension to clear a 45-degree line taken from the centre of the nearest neighbouring habitable-room window, on plan and on elevation — the rule of thumb most London officers use — so the scheme does not need a separate daylight and sunlight report.

Fees, timescales and building control

A householder planning application costs £548 from April 2026 (Planning Portal service charge on top); a Lawful Development Certificate for a proposed use is half that. Barnet has eight weeks from validation to decide a householder application; larger-home-extension prior approval is a 42-day route with a £249 fee. Party wall notices run alongside: two months for works to a shared wall, one month for excavations within 3 m or 6 m of a neighbour’s foundations. We use LABC Barnet on every project, so the inspector is the council’s own. Typical inspection points are commencement, foundation trenches, oversite and damp-proof course, drainage before backfill, structural steels and joists before they are covered, insulation and fire-stopping before plastering, then completion. We book each one and send you the completion certificate at handover.

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

“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 structural warranty.

Nearby areas

Hendon is part of our North London guide. Nearby areas: Barnet, Finchley, Enfield, Edgware, Muswell Hill, Highgate, Crouch End, Stoke Newington.

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.