London's award-winning design and build company
LCCL Construction is an award-winning design and build company based in Finchley, London N3. We provide a complete design and build service for loft conversions, house extensions, home renovations and new builds across London and Hertfordshire — managing every stage of your project under one roof, from initial consultation and architectural design through to construction completion and final handover.
With over 20 years of experience, more than 200 verified reviews rated 4.7 out of 5, and LABC Awards Regional Winners 2024 for Best Residential Extension in London, LCCL Construction has the credentials, team and track record to deliver your project to the highest standard. We are members of the National Federation of Builders and LABC Registered Partners, working directly with Local Authority Building Control on every project.
Our design and build approach means you have a single point of contact throughout your entire project. One company. One contract. One team responsible from start to finish.
What is a design and build service?
A design and build service means one company manages both the architectural design and the construction of your project under a single contract. Rather than hiring a separate architect, structural engineer, party wall surveyor and builder — and managing the communication between them yourself — a design and build company handles everything as one coordinated team.
At LCCL Construction, our in-house team covers every stage: initial feasibility assessment, measured building survey, architectural drawings, planning permission applications, building regulation submissions, structural engineer calculations, party wall agreements, project management and the full construction from groundworks to final finishing.
Why choose a design and build company?
Single point of contact
One company responsible for design and construction, eliminating miscommunication between separate architects and builders
In-house team
LCCL Construction uses its own employed team for design and project management, not a network of subcontractors
Faster delivery
Design and construction phases can overlap, reducing overall project timelines
Fewer delays
One coordinated team means decisions are made faster and approvals managed proactively
Transparent cost estimates
Detailed cost breakdowns prepared during design phase so you understand estimated costs before construction begins
LABC partnership
As LABC Registered Partners, we work directly with local building control to streamline inspections and approvals
Costs provided during consultation are detailed estimates, not fixed prices. Final costs depend on project scope, specification and site conditions. LCCL Construction provides transparent cost breakdowns at design stage.
Our design and build services
LCCL Construction provides design and build services across all residential construction types:
Loft conversions
Dormer, hip-to-gable, L-shaped, mansard and Velux
From £30,000
House extensions
Rear, side return, wraparound, kitchen, ground floor
From £35,000
Home renovations
Full house renovations, flat refurbishments, partial renovations
Contact us
New
builds
Detached, terraced, townhouses, small apartment developments
From £100,000
Architecture
Architectural design, planning permission and building regulations
From £750
Our design and build process
Every LCCL Construction project follows a structured process from initial contact through to completion:
1 / Free consultation
Free 30-minute consultation call to discuss your requirements, budget, timescales and feasibility.
2 / Measured building survey
Full measured building survey producing accurate CAD drawings of the existing structure.
3 / Architectural design and cost estimate
Full proposed drawings and detailed cost estimate covering all elements of the construction.
4 / Planning permission
Full planning application prepared and submitted. All correspondence and amendments managed. Typically 8–12 weeks.
5 / Building regulations
Detailed building regulation drawings submitted to Local Authority Building Control for approval.
6 / Structural engineer calculations
All calculations and drawings for foundations, steelwork, beams, roof structures and load-bearing walls.
7 / Party wall agreements
All notices, condition surveys and party wall awards prepared and managed on your behalf.
8 / Construction
Dedicated project manager coordinates all trades. All structural work inspected by Local Authority Building Control at each stage.
9 / Completion and handover
Full snagging inspection, all guarantees, certificates and documentation provided at handover. Optional 10–12 year LABC or NHBC warranty.
Design and build timelines
Design phase
3–4 months
Full renovation
12–24 weeks on site
Planning permission
8–12 weeks
New build
9–18 months
Building regulations
4–6 weeks
Loft conversion
8–14 weeks on site
House extension
10–20 weeks on site
Timelines are estimated at design stage and depend on project complexity, site conditions and planning authority timescales.
Construction finish options
Shell only
Structural construction to weathertight shell. Foundations, structure, roof, windows and external doors. Internal finishes by others.
Plaster finish
All structural work plus internal plastering, first fix electrics and plumbing. Ready for second fix and decoration.
Full finish
Complete project including kitchens, bathrooms, flooring, tiling, decoration, electrics and plumbing. Move-in ready.
Areas we cover
LCCL Construction provides design and build services across all London boroughs and Hertfordshire, operating within an 85-mile radius of our offices in Finchley, London N3. Our most active areas include Barnet, Enfield, Haringey, Camden, Islington, Hampstead, Highgate, Muswell Hill, Finchley, Hendon, Edgware, Southgate, Crouch End, St Johns Wood and Ealing. In Hertfordshire we regularly work in St Albans, Watford, Borehamwood, Potters Bar, Radlett, Elstree and Hertford.
What our customers say
"Alex and his team have done a fantastic job on our loft conversion and were a pleasure to work with from start to finish. I am over the moon with the results and highly recommend them to anyone." — Katherine — Trustpilot
"LCCL Construction managed the entire process seamlessly. The team kept us informed at every stage and the quality of work was exceptional. We would recommend them to anyone." — Ludovic — Reviews.io
"We have used LCCL for our rear extension and came back for our loft conversion too. LCCL has done a great job on design and construction. Would recommend without hesitation." — Mia M — Google Reviews
Featured projects
Top floor flat roof demolish & rebuild · £250k–£300k · 2025
Extension + hip-to-gable + renovation · £395k–£475k · 2024
Frequently Asked Questions
What is the difference between design and build and traditional procurement?
With design and build, one company — LCCL Construction — is responsible for both design and construction under a single contract. The traditional approach requires hiring a separate architect, then going out to tender for a builder and managing communication between them yourself. Design and build reduces risk, speeds up the process and gives you one point of contact.
How much does a design and build project cost?
Loft conversions from £30,000, house extensions from £35,000, new builds from £100,000. Architectural design from £750. All costs are detailed estimates — not fixed prices. Final costs depend on site conditions and specification. We provide transparent breakdowns so you understand what is included before committing.
Do you use subcontractors or your own team?
LCCL Construction uses its own in-house team for architectural design, project management and the majority of construction trades. Where specialist subcontractors are needed, we manage and coordinate them directly. You deal with LCCL Construction throughout.
How long does a design and build project take?
For a loft conversion or house extension, the design phase typically takes 3–4 months followed by 8–14 weeks of construction. Larger projects such as full renovations or new builds typically take 12–24 months total. We provide a detailed programme at the start of your project.
Do I need planning permission?
Many loft conversions and smaller extensions can be built under permitted development without planning permission. Larger extensions, mansard lofts and new builds always require full planning permission. LCCL Construction assesses requirements at feasibility stage and manages the entire application process on your behalf.
Can I use my own architect's drawings and hire LCCL for construction only?
Yes. If you already have approved drawings and planning permission, LCCL Construction can provide construction-only services. Send your plans to info@lcclconstruction.co.uk for a detailed cost estimate.
What warranties do you provide?
All projects are fully insured throughout construction. On completion, optional LABC or NHBC structural warranties of 10–12 years are available for new builds and major structural works, accepted by mortgage lenders.