Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Call 020 8037 7332 or get an instant estimate online.
FAQs · Costs, planning, building regulations, how we work
Loft conversion and house extension FAQs
The questions we are asked most, answered by the team that designs and builds the work. Prices are 2026 design and build figures for London; every project is priced from a measured survey, so treat them as a starting point. For a figure for your postcode in thirty seconds, use the instant estimate.
A free 30-minute phone call with our team, no obligation.
Answers
Written by the team
Prices
2026 · design & build
Updated
September 2026
Awards
LABC 2024 & 2026
Who we are
Built in Finchley, working across London and Hertfordshire
LCCL Construction was founded in 2004 by Aleksandar Madari (Anderson) and incorporated in December 2018 as Loft Conversion Company London Limited (Companies House 11713461, VAT no. GB404461526) — LCCL are its initials. The company has had the same director, the same team and the same office at Hathaway House, Popes Drive, Finchley, London N3 1QF since incorporation. We design and build loft conversions, house extensions, whole-house renovations, basements and new homes.
The idea has not changed in twenty years: the people who draw the project are the people who build it. No hand-off between an architect who has never built and a builder who has never designed, no gap in responsibility when the steel arrives, and one project manager from the first sketch to the completion certificate.
We are an LABC Registered Partner and a member of the National Federation of Builders. Our Bohun Grove EN4 project won the LABC Building Excellence Award 2024 for Best Residential Extension in London, and Weech Road NW6 won the 2026 London regional award for Best Conversion or Alteration to an Existing Home.
2004
Founded in Finchley, North London — 20+ years of design and build
2
LABC Building Excellence Awards — 2024 (Best Residential Extension, London) and 2026 (Best Conversion or Alteration, London regional)
4.7/5
200+ verified reviews across Google, Trustpilot, Houzz, Yell and Reviews.io
7 yrs
Best of Houzz Service 2020–2024 and 2026 — six awards
Go deeper
The full guides behind these answers
Costs
Every extension and loft type priced for London in 2026, with what the price includes and how postcode changes it. House extension cost →
Planning permission
Permitted development, prior approval and full applications — which route your project takes, fees and timescales. Planning permission explained →
Building regulations
What LABC checks, full plans versus building notice, party walls and the completion certificate. Building regulations explained →
How a project runs
From the free call to the completion certificate: survey, design, approvals, the build and handover. Our construction process →
The team
The people who design and build your project
%2C%20founder%20of%20LCCL%20Construction%2C%20Finchley%20N3.jpeg)
Aleksandar Madari (Anderson)
FOUNDER · ARCHITECTURE & PROJECT MANAGEMENT · 20+ YEARS
Aleksandar Madari — Anderson to everyone he works with — founded LCCL Construction in 2004 and brings over 20 years of hands-on experience in architecture, construction and project management.
He oversees every project from initial design through to completion. His background spans architectural design, planning applications, structural engineering and on-site construction management, with particular expertise in loft conversions, house extensions and new builds across London and Hertfordshire.
Amelia Taylor
ARCHITECTURE & PROJECT MANAGEMENT · 16 YEARS
Amelia Taylor has over 16 years of experience in architecture, project management and construction.
She manages the design and delivery of projects from initial consultation through to handover, coordinating with architects, engineers and construction teams throughout. Amelia specialises in residential projects including loft conversions, house extensions, renovations and new builds, with a strong track record of delivering work on time and to a high standard.
%2C%20LCCL%20Construction.png)
Sarah
ARCHITECT · ARB · RIBA
Sarah handles architectural design, concept development, planning permission applications and building regulation submissions.
Her detailed knowledge of local authority planning guidelines across London and Hertfordshire enables her to achieve a high rate of planning approvals. Sarah produces technical drawings for loft conversions, house extensions, new builds, basements, renovations and outbuildings.
%2C%20LCCL%20Construction.png)
Steven
ARCHITECTURE & SURVEY · MCIOB · FPWS
Steven handles architectural design, concept design, planning applications, building regulations approvals and technical drawings.
He works across loft conversions, house extensions, new builds, basements, renovations and outbuildings. Steven is a member of the CIOB and the Faculty of Party Wall Surveyors (FPWS), and his knowledge of London and Hertfordshire councils helps us achieve a high rate of planning approvals.
Hip-to-gable loft, full-width rear extension, two new bathrooms, whole-house renovation, landscaping and a regulated outbuilding. LABC Building Excellence Award 2024 — Best Residential Extension in London. Read the case study →
Top-floor flat converted into a penthouse duplex: kitchen and living space moved into the new loft, two bathrooms, an extra bedroom. LABC Building Excellence Award 2026 — London Regional Winner, Best Conversion or Alteration to an Existing Home. Read the case study →
“We are very happy with the services from Lccl, Alex has done a great job on design and construction. 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.”
Mia M · Google Reviews
“The Lccl construction team built my extension with a quick and clean service, they worked non stop through the winter weather.. I would highly recommend this company!”
Chris Dunn · Google Reviews
“LCCL Construction was the right company to help with my loft conversion. I heard of other people's challenging experiences with building works so I was very careful which company I chose. LCCL Constructions was professional, trustworthy and worked to the…”
KashImaging · Trustpilot
Costs · Planning · Building regulations · Working with LCCL
Sixteen questions, answered
In 2026, design and build inclusive: a single-storey rear or side return extension £42,000 – £93,600 inc. VAT (£35,000 – £78,000 + VAT), a wraparound £72,000 – £153,600 inc. VAT (£60,000 – £128,000 + VAT), a two storey extension £90,000 – £198,000 inc. VAT (£75,000 – £165,000 + VAT). Inner London adds 10–15%, Central London 20–25%, Hertfordshire is about 5% less. The kitchen and bathroom fit-out is priced on top. The instant estimator gives you a figure for your postcode in thirty seconds.
£56,400 – £80,400 inc. VAT (£47,000 – £67,000 + VAT) for a rear dormer with a bedroom and en-suite, and £58,800 – £98,400 inc. VAT (£49,000 – £82,000 + VAT) for an L-shaped dormer that adds a second room over the outrigger on a terrace. Both are usually permitted development.
Yes. Every figure on this site is shown inclusive of VAT at 20%, with the ex-VAT figure in brackets — Loft Conversion Company London Limited is VAT-registered (GB404461526). New-build homes are zero-rated. The figure on your itemised estimate is the figure you pay — nothing is added afterwards.
A new kitchen unless you add it as a line in the instant estimate (supplied and fitted, typically £9,000 – £87,360 inc. VAT (£7,500 – £72,800 + VAT) by size and specification; appliances extra), flooring and second-fix items you choose, bespoke joinery, landscaping, council planning fees, and party wall surveyor fees if a neighbour dissents (from £750 per neighbour). Everything else — survey, design, approvals, structure, build, LABC sign-off and guarantees — is in the price.
Two steps. The instant estimator gives you a range for your postcode and project in thirty seconds. Then one measured survey gives you a detailed itemised estimate — design, planning, structure, construction and warranty priced line by line — with no obligation.
Usually not for a single-storey rear or side return extension — they are permitted development and we obtain a Lawful Development Certificate. Wraparounds, two storey extensions, flats and conservation-area houses need a full application with an eight-week decision. We check your address before the first drawing.
The permitted development volume allowance for roof extensions: 40 cubic metres on a terraced house, 50 on a semi-detached or detached house, measured on the original roof and including any earlier roof extension. A typical rear dormer uses 25–35 m³; an L-shaped dormer on a terrace can use all 40. We measure the volume at the survey before promising a route.
A certificate from the council confirming that your extension or loft is permitted development and does not need planning permission. It is optional in law but we obtain one on every permitted-development project: it costs half the householder fee, takes up to 8 weeks, and it is the document your buyer's solicitor will ask for when you sell.
A council order that removes permitted development rights in a defined area, usually a conservation area. In an Article 4 area even a small rear extension or a rear dormer needs a planning application. We check the council's Article 4 schedule for your address before the first drawing — it changes the route, the fee and the timescale.
Not if it is permitted development within the limits — there is no consultation. On a prior-approval (6 m / 8 m) extension the council notifies the adjoining neighbours and only an objection triggers an assessment. On a full planning application neighbours can comment and the officer weighs daylight, outlook and privacy. Talk to them first; we will show them the drawings with you.
Yes. Planning and building regulations are separate: permitted development removes the need for planning permission, never the need for building regulations. Every extension, loft conversion, basement and structural alteration needs building-control approval and a completion certificate.
On a terrace or semi, whenever the work cuts into, builds on or excavates near a shared wall — which is nearly every extension and loft. Notices 2 months before (1 month for excavation); most neighbours consent; a surveyor only if one dissents. We serve the notices and manage the process.
Typically 8–16 weeks of design and approvals, then 4–24 weeks on site depending on the project — a rear extension is on site 10–14 weeks, a loft 4–16, a two-storey extension 18–26, a new build 30–50.
A booking fee on signing reserves your start window. The build is then paid in stages set out in the Schedule of Works: each stage is invoiced when the previous one is complete and paid, by bank transfer, before that stage starts. The stage sums are fixed in the signed schedule, so there are no surprises.
Often, for an extension or loft — much of the work is outside or above the existing rooms. A whole-house renovation or basement is different. We tell you at the survey what is realistic for your project.
A 12-month workmanship guarantee from LCCL on every project, plus a 10-year LABC structural warranty available on every project — issued by LABC Warranty in your name, so it does not depend on the builder still trading. Building control sign-off is through LABC — we are an LABC Registered Partner and LABC Building Excellence Award winners in 2024 and 2026.
%2C%20founder%20of%20LCCL%20Construction.jpeg)