Design and Build London 2026: Complete Guide to What It Is and How It Works

Design and build is the most efficient way to deliver a loft conversion, house extension, renovation or new build in London. Instead of separately appointing an architect and a builder — and managing the communication between them yourself — a design and build company handles every stage of your project under one roof. LCCL Construction is one of London's leading design and build companies, delivering loft conversions, house extensions, home renovations and new builds across London and Hertfordshire for over 20 years.

LCCL Construction — award-winning design and build company in London and Hertfordshire

What Is Design and Build and How Does It Work?

Design and build is a construction delivery method where a single company is responsible for both the architectural design and the construction of your project. At LCCL Construction our design and build service covers every stage: initial measured building survey, architectural design and drawings, planning permission application, building regulations application, structural engineer calculations, party wall agreements, project management and construction through to completion. You deal with one company and one dedicated project manager throughout.

Design and Build London: The Key Benefits

One point of contact: You deal with a single company throughout the entire project rather than coordinating between a separate architect, structural engineer and builder. This eliminates the communication gaps that cause the majority of construction disputes and delays.

One clear estimate: Because the same company is responsible for both design and construction, the estimate accurately reflects the cost of building the design. There are no surprises when a separately appointed builder prices up an architect's drawings.

Faster delivery: Design and build projects typically complete faster than traditionally procured projects because design and construction can overlap. There is no gap between completing the design and appointing a builder.

Single accountability: If anything goes wrong, there is one company responsible. This eliminates the situation where an architect blames the builder and a builder blames the architect.

What Does Design and Build Include at LCCL Construction?

Design phase: Measured building survey, existing and proposed architectural drawings, planning permission application, building regulations application, structural engineer calculations, party wall notices and agreements, project management and administration.

Construction phase: All groundworks, foundations, structure, roof, glazing, first fix electrics and plumbing, insulation, plastering, second fix electrics and plumbing, decoration and finishing. All projects are fully insured and eligible for the optional 10-year LABC structural warranty.

How Much Does Design and Build Cost in London in 2026?

Design and build costs in London vary by project type.

Loft conversion: £30,000 – £144,000 inc. VAT (£25,000 – £120,000 + VAT).

House extension: £42,000 – £180,000 inc. VAT (£35,000 – £150,000 + VAT).

Home renovation: £36,000 – £240,000 inc. VAT (£30,000 – £200,000 + VAT).

New build: £270,000 – £500,000 (zero-rated for VAT — new homes carry no VAT)+.

All costs include the full design and build service. See our detailed cost guides for loft conversions and house extensions.

Why Choose LCCL Construction as Your Design and Build Company in London?

LCCL Construction is an award-winning design and build company based in Finchley, London N3. Over 20 years experience. 350+ completed projects. 200+ verified reviews at 4.7/5. LABC Award Winners 2024 for Best Residential Extension London. LABC Registered Partners and members of the National Federation of Builders.

Frequently Asked Questions About Design and Build in London

What is the difference between design and build and traditional procurement?

In traditional procurement you separately appoint an architect to design the project and then get builders to quote for construction. In design and build one company handles everything. Design and build is typically faster, less stressful and provides clearer cost certainty.

Is design and build more expensive than using a separate architect and builder?

Not necessarily. While design and build companies include design fees in their estimate, you avoid the cost of separately appointing an architect and the risk of construction costs exceeding the architect's estimate. The total cost is typically similar or lower with greater certainty.

To discuss your project with LCCL Construction call 020 8037 7332 or get an instant quote online.