20+
Years Experience
200+
Verified Reviews
4.7/5
Average Rating
1 Team
Design, Build & Guarantee
350+
Projects
House Extensions and Loft Conversions in London — Design & Build From One Team
Architecture, planning, construction and finishing — all under one roof. Based in Finchley N3, covering London and Hertfordshire. NFB Membership
About LCCL Construction
LCCL Construction is a design and build company based in Finchley, North London. We specialise in house extensions, loft conversions, home renovations, new builds, and full architectural services.
With over 20 years of experience and more than 200 reviews rated 4.7 out of 5, we handle every stage of your project — from initial design and planning through to construction and final handover. One team, one point of contact, one company accountable for the result.
We won the LABC Building Excellence Award for Best Residential Extension in London 2024. We are members of the National Federation of Builders and LABC Registered Partners.
What Our Clients Say
Extremely professional and personable company - highly recommended
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, 7 February
Very happy with the services provided…
In just over 6 months LCCL they managed to transform my damp, musky, 1900s mid-terrace house in dire need for repair into a clean and modern living space - loft conversion, full rear extension, patio, outside rendering fixes, new doors and windows and complete electrics and plumbing rehaul - ...
Matt EL, 01 July
LCCL Did An Excellent Job
Reliable, fast, trustworthy and very organised we had many people on site working at the same time and the work progressed very quickly. Our extension and loft conversion look great and we would recommend.
Alex Gray, 24 May
Accreditation, partnerships and planning
Our Services
Everything from architectural design and planning through to construction and finishing — all under one roof.
Add a bedroom, bathroom, and significant value without losing garden space. Dormer, hip-to-gable, L-shaped, and mansard conversions. From £18,000
Open-plan kitchens, extra bedrooms, wraparound living spaces. Rear, side return, double-storey, and wraparound extensions designed and built by one team. From £35,000
One company from first sketch to final finish. Architecture, planning, construction, and project management — all under one roof. From £750
In-house architects and structural engineers. Measured surveys, planning drawings, 3D visualisations, building regulations, and party wall agreements. From £750
Full house refurbishments, kitchen and bathroom renovations, structural alterations, rewiring, replumbing, and complete interior fit-outs. From £25,000
Complete new build and knock-down-rebuild projects. Architecture, planning, construction, and finishing from foundation to handover. From £250,000
How it works
From first call to moving in — here’s what to expect.
Step 1: Free Consultation
We listen to your ideas, and give honest advice on what’s achievable. No obligation, no hard sell.
Step 3: Planning & Approvals
We handle planning applications, building regulations, structural engineering, and party wall agreements. You approve the designs — we do the paperwork.
Step 5: Handover
Final inspections, building control sign-off, and your Optional 10-year LABC warranty. We don’t leave until you’re completely satisfied.
Step 2: Design & Estimate
Our architects produce detailed drawings. You receive an estimate — architecture, planning, construction, and warranty.
Step 3: Construction
We build it. Your dedicated project manager coordinates every trade on site. Regular updates keep you informed at every stage. Typical builds take 10–20 weeks depending on scope.
Our Work
A selection of recent projects across London and Hertfordshire.
Areas We Cover
Based in Finchley N3, serving London and Hertfordshire.
North London & Hertfordshire
Barnet | Finchley | Hendon | Muswell Hill | Edgware | Enfield | Borehamwood | Potters Bar | Watford | St Albans
Across London
Hampstead | St Johns Wood | Islington | Kensington & Chelsea | Fulham | Clapham | Richmond | Putney & Wandsworth | Crouch End | Stoke Newington | Highgate | Ealing | Notting Hill | Camden | Queens Park
Regional
London | North London | East London | South East London | Hertfordshire
Why LCCL Construction
One Team, Every Service
Architecture, structural engineering, planning, construction, and finishing — all in-house. No subcontractors you’ve never met.
Award-Winning Quality
LABC Building Excellence Award winners 2024 for Best Residential Extension in London.
Estimated Detailed Costs
Architecture, planning, building control, construction and optional warranty included.
20+ Years Experience
Architecture, structural engineering, planning, construction, and finishing — all in-house. No subcontractors you’ve never met.
200+ Verified Reviews
4.7 out of 5 across Trustpilot, Reviews.io, and Houzz. Read what our clients say.
LABC 10-Year Warranty
Optional warranty underwritten by the UK’s largest network of building control professionals.
Frequently Asked Questions
Q: How much does a house extension cost?
Costs depend on size and specification. Single-storey rear extensions typically start from £35,000, double-storey from £100,000, and wraparound extensions from £85,000. We can include architecture, planning, construction and a optional 10-year LABC warranty or entirly bespoke tailored design and build package.
Q: How long does a loft conversion take?
Most loft conversions take 8 to 12 weeks on site. Allow 8 to 12 weeks before that for design, planning, and building regulation drawings. Total timeline from first contact to completion is usually 4 to 6 months.
Q: What’s included in your price?
Depends on what level services you need, can be everything, partial or just shell finish. Architectural design, structural engineering, planning applications, building control, project management, all construction, and a optional 10-year LABC warranty. No hidden extras. Subject final designs.
Q: Do you handle planning permission?
Yes — completely. Our in-house architects prepare all drawings and submit directly to your local council. This includes full planning applications, Lawful Development Certificates, and heritage statements for conservation areas.
Q: How do I get started?
Call 020 8037 7332 or book a free consultation online. We’ll visit your property, discuss your ideas, and give you honest advice with no obligation. Most consultations are arranged within a few days.
